Part 11 - cd3wd411.zip - Offline - 04

Part 11 - cd3wd411.zip - Offline - 04
OFICHE
REFERENCE
LIEWWII
A project of Volunteers in Asia
by: Ian Bradley
Published by:
Model and Allied Publications
Argus Books Limited
P.O. Box 35, Wolsey House
Wolsey Rd., Hemel Hempstead
Hertfordshire BP2 4SS England
Paper copies are $ 7.80.
Available from:
META Publications
P.O. Box 128
Marblemount, WA 98267
U~SA
Reproduced by permission of Model and Allied
Publications.
Reproduction of this microfiche document in any
form is subject to the same restrictions as those
of the original document.
MVWSD
MANUAL
The authcr, Ian Brz,dley enjoys
a hick8 reputation
mongst
model and light enginae:s for
his “vide knowledge
of the
subject and a happ’r knack of
explainingquite
involved operations in a clecr and iogical
manner. This bcok is designed
to assist and instruct tne newcomer to the craft in the allimportant matters of planning
and !ayout of the home workshop, the selection of handtool&
their correct use, and, finaliy,
shovvs the reader ho*& to apply
his newivdeveloped
skill to the
making of additional items for
his workshop. The book then
goes on to deal with the
selection,
installation,
maintenance, and practical uses of
machine
tools. Primarily
for
beginners this is a book which
C?V&Ti the
most experienced
worker will find abounding in
useful hints and tips.
ML7
LATHE
Yhe purpose of this book is to
give practical assistance to all
users of metal working lathes,
and can be used as a workshop
companion.
The methods and
accessories described apply to
Myford
lathes, but the book
will be of service to every lathe
worker.
0 55242
342 X
THE AMATEUR’SWRKSHOP
This work
fits in no small
measure
that
much abused
deac; iption of a “vade mecum”
for the enthusiast, who will so
often be largely self-taught and
in need of the help such a
comprehensive
him.
work
can give
No less than thirty-one chapters
deal with all phases of turning,
rmilling in the lathe, dividing in
the lathe, the use of measuring
instruments,
shaping, drilling,
knurling,screw-cutting,
belt and
overhead drives, compressed air,
reamers.
0553440492
Model
& Allied
Publications
Argus Books Limited
Station
Road,
Herts. England.
King’s Langley
f3.00net
in U.K. only
ISBN 0 85242 428 0
IAN BRADLEY
MODEL
& ALLIED
PUBLICATIONS
ARGUS BGGMS LTD
Station
Road,
Kings Langley,
England
Hertfordshire
New, completely revised edition 1975
Reprinted 1976
M1 rights reserved.
$? Model & Allied Publications
ISBN
o 85242
1967,
428 o
Printed in Gr2a.t Britain by
REDWOOD
BURN
Trowbtidge
LIMITED
& Esher
1975
INTRODUCTION
this book is intended primarily for the ever
increasing number of those fitting up small workshops in
the home, when adopting light engineering work and model
engineering as a hobby, the more experien.ced worker may
find in its pages much of practical interest.
‘Within the space available it is hardly possible to do
more than start the novice on the right road, but as his
skill a,nd experience grow he will, we hope, be able to profit
from the more advanced publications
available on this
subject.
In order that progress, both in equipping the workshop
and in the use of tools, may be made step by step, Part I
of this book has been devoted to hand tools, whilst in Part
II the selection and practical use of the electrically-driven
drilling machine, the grindiug machine, and the lathe
are described.
Moreover, to help the novice to gain proficiency and to
maintain his interest, some examples of work have been
included which will not only enable him to put his reading
into practice but will, at ,the same time, serve to add to his
workshop equipment.
AI.THOWH
Hungerford
I g 75
CHAPl’EK
PLANNING
ONE
A WORKSHOP
Genera: Considerations-Benches-Storing
Tools
--Tool Racks-Shelvin,g-Cupboard-Chests
of
Drawer--Heating
and Lighting-The
FloorMethodical Working
CHAPTriR
WORKSHOP
TWO
EQUIPMENT
The Vice - Hand Tools -Files - Hacksaws y
Hand Drills-Drills-Screwthreading
Equipment
-- Shears ----Chisels - Scrapers .- Tools used for
Assembl!‘tzg Work - Spanners - Sc~ewdriuersPliers - Dcmmers -’ Punches - Soldering Equipmm--Oil
Stones
CHAPTER
‘THREE
EQUIPMENT
FOR
MEASURING
AND
4I
C?ilipers--Rulers--Micrometers-De#th
Gauge‘The Protractor-Drill
Gauge-Marking
OutEquijmnent Required-Marking-out
Sheet Metal
Work- Witness Lines--Marking-out Solid Objects-Marking-out a Bearing Bracket-Markingout the Centre of a Shaft-Reading
Machine
Drawings
MARKING-OUT
CHAPTER
CHAPTER
66
Filing - Pinning -Draw
Filing - Filing Aluminium - Scraping - Sawing Metal - Markingout the Work -- Using the Hacksaw - Sawing
Curves - Cutting Metal-Cold
Chisels - HandDrills - The &Ring
Operation-Polishing Reaming-Screw
Threading-Cutting
ThreadsSoldering-Hardening and Tempering
FOUR
FIVE
USING
HAND
TOOLS
TO hfAKE
A Simple Depth Gauge-A
TOOLS
Rule Stand
300
CONTENTS
CYLAPTER
ONE
THE
PART
DRKLlriG
II
109
?vtACHINE
Lever-feed and Rack$ed Type.:, .-ElectricDrilling
Machine - Driving the X~3ne - Drilling
Speeds---Machine Vice-Table
V Blocks- Work
Clamp---Drill Chuck-Table StopDepth-drilling Stop and Gauge-Drilling
t+erations-Drilling into a Cross-hole-Drilling
on an
Inclined Stirface-Cross-drilling Shafts-,Drilling
for Tapping-Tapping
in the Drilling Machine
-Countersinks-Counterbores and Pin Drills
CHAPTER
TWO
THE
GRINDING
135
MACHINE
The Grinding Head-Driving
the MachineElectric Grinding Machine-Angular
Grinding
Rest - Grinding Operations- Grinding Twist
Drills
CHAPTER
THREE
THE
147
LATHE
General Description-Types
of
-Methods
of Driving-Lathe
Lathe Maintenance
CHAPTER
FOUR
DFtIVING
MACHINE
Small Lathes
Accessories-
TOOCS IN THE
WORKSHOP
163
Setting out the Machine Tool Bench-Linesha@
and Gountershaf?s-Direct Drive from Electric
Motors-Installation of Motors
CHAPTER
FIVE
OPERATING
THE
173
LATHE
Lathe Tools-Measuring
Instruments-Chuck
Work.---Sliding-Surfaciq-Boring-Use
of th
Face@late- Turning Work between Centres-‘.~Mounting the Work-Use
of Steadies---Boring Work on the Saddle-Drilling from
the Tailstock-Depth-drilling-The
D BitTapping and Dieing-Screwcutting-Turning
&th Hand Tools
CHAPTER
SIX
TOOLS
AND
EQWIPMENT
TO
MAKE
211
Colleted Die Holders-Drilling
Machine TQ~Countersink-Fin
Drills--Ping Handle-A
Drilling Machine Table Stop-Gentre Finder
-Angular Rest
INDEX
DRAWINGS BY IAN BRADLEY
239
EGINNER’S WORKS
Part I
CHAPTER
ONE
General
Considerations
-~~ Benches Storing Tools-Tool
Racks-ShelvingCupboards-Chests
of Drawers--Heating and Lighting-The
Floor-Methodical
Working.
:~
I,
,,,
:I,,;
:
1~ my own first workshops are any guide, you must not
expect to start with a fully-equipped shop. For one thing,
this would be expensive, and, on the other hand, you
could hardly expect to be able, straight
away, to make proper use of a large
number of special tools. Far better. to
start with a few good quality simple
tools and to add to these later on as they are required.
The question of the quality of the tools must be stressed ;
always buy the best tools you can afford or are otherwise
able to procure. Do not be ‘put off with any poor quality
equipment that may be offered to you, and, when’ buying
tools, you will find it a good plan to persuade a friend with
krowledge of the subject to accompany you, for if he is a
practical man his timely help may save you much disappcintment
later on.
A good tool will last a lifetime, and the money spent on it
will be amply repaid by years of good service.
As the choice of tools calls for some experience, I shall
give later some hints on what to lodk for and what to avoid
when buying tools.
First of all, however, the question of the workshop itself
must be considered.
If you have a parent or 9 relation who is himself a model
engineer 31: is interested in the use of tools, in all probability
this question will already have been solved. If not, it will be
a ma,tter of persuading the household authorities to let you
1
2
have a place, bz it a room, an outbuilding, or even the
corner of a room, in which to pursue your hobby so that
YOU can ivy out your tools without causing inconvenience
to others, and without fear of !nterruption while at work.
The household authorities may not, at first, take kindly
to workshop activities within the house, but, ifyou fortn the
habit of working in an orderly and tidy manner, any
objections raised should soon cease when it is seen that you
are considerate as well as being intent on your work.
Try, if you can, to get leave to work in the house, as this
will make a big difference to the comfort of working in cold
weather.
Outside workshops require heating during the colder
months, both to make working possible and to prevent
rusting of your tools by damp.
However, there may be no facilities for establishing an
outside workshop, and assuming that the use of a room for
this purpose has been granted, the question arises as to how
it shall be fitted up. Obviously, the first requirement will
be a good strong bench, big enough to give plenty of room
for working. The bench can be either built on to the wall,
where the construction
of the house allows, or if it is
robustly made, it should be steady when standing on its
own feet.
To facilitate working, the bench should be placed in the
best light, and it is suggested that, to begin with, it should
be installed under the window so that the worker faces the
light, as shown in Fig. I, which shows the bench as seen
from above.
At the outset, at any rate, the bench will have to serve
the novice for all purposes, including a mounting for the
vice, as will be described later.
As additional equipment, shelves will be required as well
as tool racks and, per-hap s, cupboards to house the tools
needing greater protection.
Fig. 2 shows the workshop as
it will now appear with this equipment in place ; the bench
seen fin the foreground is that illustrated in Fig. I.
If you are fortunate enough to have the use of a room with
i3E.NCt-t
Fig. I
Fig.
2
u = WINDOWS
Fig. 3
1
a larg: wi ldow which is carried outwards and returned on
two s-~icS.. that is to say a large bay-window, this can be
ma&
into an excellent and well-lighted workshop, as
iHustra3I in Fig. 3.
Th(: &awing shows the arrangement in plan, that is to
say !,hc~hird’s-eye view, and it will be seen that two main
benches \3reshown, one for general light work, and the other
to carry ((he vice and the machine tools as they are acquired ;
in addir+n, a heavy marHe siab, which will be described
later, f;z.’ been fitted into the window corner for doiug small
work ~,!tjl the best possible lighting.
Ada~&edly, this is.an advanced. layout, but it is, nevertheless; Gel1 worth ixxiag
in mind as an ideal and as a
futwrc lx,ssibility ; ) CG:when. arranging the workshop, work,
if you can, to a deErrite plan with a view to acquiring and
inst;;!iii:g at so::z future date all the tools needed to fulfil
your a.mbition:;. By so doing, constant rearrangement
of
the i.~ixkshop can be avoided, and only tools useful for all
time will be acquired.
BeiTches. ~-ashas. pxviously been sai;l, the bench should be
prefc:rably (of rc,$,<1 construction and sufficiently firm on
its iegs to gil.le sr~.~diness when working. A suitable design
is stox?:n in Fig. 4. The legs should be at least 3 in. square,
aud th I’ top on which the .vice is mounted should be made of
r4ar.k: .I in. thick.
5
If you have had some experience of woodworking
and
can obtain the necessary materials. you may be able to
make the bench yourself, but if net? it may be possible to
buy a bench at a sale or horn a furniture store. Failing this,
a robust form of kitchen table may be used, at any rate as
a start.
In the drawing of the bench shown in Fig. + it will be
seen that an undershelf is fitted ; this is useful not only as
a storage place, but if heavy material is kept there it will
help to steady the bench and prevent it moving when heavy
filing is undertaken.
As previously mentioned, a slab, as shown at the righthand top corner of Fig. 3 can be used for doing small work.
1 used a heavy marble slab which is fixed to the window
sills with wood screws. These slabs form the tops of washstands of a t.ype now seldom used, and the complete piece
of furniture can often be picked up at a sale for a few
shillings ; the woodwork will come in useful for making
tool racks and shelves.
Now, as these marble slabs are very heavy, they will form
a steady f’o:.lndation for mounting a small vice of the type
that is ma& i‘?ith a clamp for attachment to the bench ; in
addition, these slabs usually have screw holes for fixing in
place.
This little extra bench will be found most useful for doing
rig. 4
6
_.--
-’
small work oQX’making
drawings, as in this position it
w!ll be w&‘Gghted and at a convenient’height
for working
;&en the operator is seated on a stool of the office pattern.
Storing lock
As has already been pointed out, if the
workshop is filtei out in a living room, any untidiness will
almost L.-vi~;
,,..niy call for reproof, and, morenver, tools left
lying about are easily mislaid or damaged.
“ A place for
everythin: and FvVrerythingin its place ” is a good rule to
ibiollow.
ISt~::~eworke-3 &ep their tools in racks and on shelves
near at hand, 133~ however convenient this may be, it has
its 3awback.ij
:c: the room is not then easily kept clean,
n.;rd also some sir;’ the finer tools may be damaged by
e-rposure to &.;,::l,
For these resons,
and perhaps also for- the sake of
a.ppearan;e, &IW-S may prefer to store the workshop tools
in cupboard2 .,I=in small chests of drawers, where they are
out,, of sight ~;;d ,well protected against damage and casual
borrowers.
In the course of time, it is almost inevitable that a great
variety of materials and parts such as screws and nuts and
bolts will be accumulated in the workshop, and it is very
necessary that they should be stored in an orderly and
methodical manner, so that, for example, any particular
size of scr&;\I can be found at once and without having to
rumrr:q
In a box full of oddments.
Tobacco and cigarette tins are excellent for this purpose,
so collect all you can from your friends and keep them in
readiness ii. irceive your purchases of screws and other small
material
Glass C::G:Gng soap jars with screw tops are also most
useful, fez :F the con:::nts are always visible this may save
opening box-es to find what you want. If the lid is attached
w2h wood screws to a beam or batten, as shown in Fig. 5,
the jar will take, up very little valuable space and can be
readily unscrewed to get at its contents.
Cigar b’;rY.cs,when obtainable, make useful receptacles for
storing larger accessories and material.
..-__
I
----
-
Fig. j
it is hardly necessary to mark glass jars to
indicate what they contain, tins and boxes should always be
labelled to save time when looking for materials of any
particular size.
For this purpose, the titles may be painted on, preferably
with cellulose paint which dries quickly and adheres firmly,
but it will usually be found sufficient to attach a gummed
label, or a piece of sticking plaster, on which is written
a list of the contents.
Tool Racks. When the to& are kept in racks, these can
be easily made by attaching a leather strap or strip, or a
piece of webbing, to- a length of wood which is then fixed
to the wall or window framing. The design of a simple tool
rack is illustrated in Fig. 6.
Ahhugh
WOOD
LEATHER
STRIP,
-STRIP
Fig. 6
8
\l’hen attaching tool racks and other wrorkshop fittings to
the walls of the room, do not use ordinary nails, as these
generally have but little holding power, and when they work
loose, as in time they will, the wall will probably be much
damaged and hard words may result. On the other hand,
if Rawlplugs are properly used, the hold wiil be firm and the
walls will not suffer.
Before using Rawlplugs within th;: hause, it is a good plan
to practise a few holes in a place that does not matter, but
with ordinary skill, and if reasona’ble care is taken, no
difficulty will be found in fitting these useful fixings.
Sheiving. Within the house, built-up shelves like book
shelves wil.1generally be used, either standing on a cupboard,
or fixed ta thz wall by means of Rawlplugs ; only in the
case of a shed lvorkshop will iron shelf brackets be employed
to support lines of shelving, In every case, tbc she!ves must
be securely fixed, so that they do not fall when loaded with
heavy tools.
Cupboards. Smal 1 cupboards are particular!y usefulj as
they afford good protection for the tools and, at the same
time, may even enhance the appearance of the workshop.
Furthermore,
the tools can then be locked up to guard
against would-be borrowers.
If possible, cupboards should be placed so that their
contents are in fu!l view and can readily be removed when
wa.nted without having to go down on the-hands and knees.
When large cupboa.rds are fixed to walls it may be necessary
to use brackets to give additional support.
Chests of Drawers. Although there are many forms of this
article of furniture, one of the most useful is the musi.c
cabinet, which usually has some six wide but rather shallow
drawers that are ideal for storing files and similar types of
tools, where it is important
that the tools should not
become damaged by being heaped one upon another.
Another’form of chest, which can often be picked up quite
cheaply at sales, is the Wellington chest. This, again, has
six or more drawers placed one above another, but, in this
case, the individual drawers, being narrower and deeper,
9
are suitable for holding larger tools and ot.her items 01
workshop equipment.
With an ample supply of cupboards and chests of drawers
all the workshop tools can, if desired, be stored out of sight
so as to preserve the good appearance of the room and
disguise its real purpose.
Should the air of the room be liable to become damp,
this dampness will be absorbed by the woodwork so that
tools kept on wooden, shelves mzy be damaged by rust ; this
is more likely to occur when the shelves are covered with
paper, for ordinary paper readily absorbs ,moisture. To
prevent rusting, therefore, from this cause, all wooden
shelves should be covered with some material, such as
plastic sheeting, which does not absorb water.
Even this precaution will not safeguard the tools from
r-i.ac;n,7
;., 3 il..,U
chd
.11
..n.Gch
.-. ..APWP
thz.ra
I LL.,““,5 111
vli~s*Ior
‘V rnn+;n,.r\r.r
~“IILI..Ll”U.J
“ll.bLb
Cll’irlC :r
AU pfi
heating,
and in this case, the tools should be oiled or
greased, preferably with a compound such as Rustveto,
which is specially made for this purpose and contains
lanoline or wool fat to render the coating impervious to
moisture.
Heating and Lighting. In factories a reasonable temperatu,re of the air is maintained not only for the comfort of the
workpeople, but also to enable them to do good work and
keep up the output. For the same reasons, the heating of
the home workshop is equally important, and within the
house this should not be a difficult matter, but in theshed
workshop it will probably be necessary to use some form of
stove if work is to be carried on during the winter months.
As the workshop will probably be largely used after dark,
satisfactory artificial lighting i.s essential if good work is to
be done. The general lighting with which the room or
shed is equipped will probably not be sufficient for fine
or difficult work at the bench, and some form of additional
lighting will then be required. For this purpose, a movable
form of lamp, such as a reading lamp, will be found an
advantage, for then the light can be directed to the exact
spot where it is most required.
The Anglepoise lamp,
10
manufactured by Messrs. Terry, is made in two sizes, and
the larger when standing on the bench is instantly adjustable to cover a \vide area, so that it should alone be able
‘0 provide all the light necessary for working at the bench,
or for using any machine mounted on the bench top.
The Floor. In order not to add to the work of keeping the
room clean and tidy, care should be taken to prevent, as
far as possible, filings and lathe turnings from falling on the
floor ; for not only are these difficult to sweep up, but also,
when they are trodden about the room generally, censure
is almost sure to follow.
To overcome this difficulty, an old mat should be spread
on the floor underneath the vice where it will catch the
filings as they fall ; it is then an easy matter to take the mat
outside and shake it clean. In the same way, mats can be
>rwcl
UULUtr
L” --t-h
CiiiL.ll the cf;ips i!;zt &‘;ili fI-orlr tile lathe or &-ijiing
machine.
It will be found that chips and filings are easily trodden
into lino or soft wood floors and are then difficult to remove,
so take special care to protect the floor from damage of this
kind.
The bench top should always be brushed clean after
working, and the chips, when collected in a domestic dustpan, should either be taken outside at on:e, or placed
temporarily
in a box kept for the purpose under the
bench.
Finally, train yourselffrom the start
Methodical Working.
to follow a tidy and methodical way of working, so that
tools are put back in their places as they are used and you
do not waste time and temper in searching for them amongst
a heap of tools cluttering up the bench. When taking work
to pieces, place the screws and other small parts in a tray,
such as the lid of a tobacco tin, and you will not then have
to search the bench, or possibly the floor, for missing parts
when it comes to putting the work together again.
As an example of what is meant by this, when overhauling a motor car engine I used a wooden block drilled
with a numbered hole to receive each valve as removed,
1 I.
and set with nails for holding the spring, cellar, and cotter
belonging to each valve.
In this way: the parts were readily reassembled in theit
original order, and there was no danger of their not
working properly owi,ig to wrong assembly.
Although this was in the early days of motoring when all
parts were hand-fitted and not mass-nroduced, the former
method of fitting is still used in some branchrs of engineering, and nothing is lost, and probably much is gained,
by working methodically when overhauling any kind of
mechanical work.
The
Vice-Hand
Tools-Files-Hacksaws - i-land Drills - Drills - Screwthreading Equipment-Shears
- Chisels
-Scrapers-Tools
used for Assembling
Spanners Screwdrivers Work Pliers Hammers Punches Soldering Equipment-Oil
Stones.
I;,:,
1~
I
I
I
The Vice. Before any filing or sawing of material can be
undertaken it will be necessary to attach a vice to the bench
ior the purpose of holding the work secureiy ; and although
the vice must, of course, be firmly fixed
in place, its weight also helps to steady
the work.
It is important, therefore, that the vice should be fully
big for its purpose and capable of holding the largest
material that is likely to be used.
For general work, a vice of simple design and with jaws
not less than 4 in. in width wil as a rule be found most
suitable.
A well-designed and robust type of vice is illustrated in
Fig. 7, and from the cross-section of this appliance shown in
Fig, 8 it will be seen that the jaws are closed by means of a
square-threaded screw working in a threaded nut attached to
the body casting. Although these screw threads are well
protected from filings, nevertheless, they should be well
oiled from tome to time to prevent undue wear taking place
and to enable the parts to work freely.
As will be seen, the two jaws carry detachable hardened
steel jaw plates which have roughened surfaces to enable
them to grip the work more securely, but as it is generally
an advantage to have smooth jaws which do not damage
finished work, you may be able to get someone to grind
12
13
these flat for you, or, perhaps5 you can bu:? in the first place
a vice with unroughened jaws.
To prevent the surface of finished work being damaged,
two strips of sheet lead or copper shouki be gripped between
the jaws and then hammered over to retain them in place
WhCfi thC vice iS OpeIlc. -d ; these fittings, known as vice
clams, are illustrated in Fig. g. Clams are also procurable
made of thick red fibre and fitted with metai clips to hold
them in place on the vice jaws. Strips of cardboard will
also be found useful as
clams when gripping
small work.
The vice is secured
to the bench top by
means of large wood
screws; or prcfxa’biy
with
carriage
bolts
which have a screwthreaded shank and a
head to fit a spanner.
Fig. 7
Fig. 8
14
Fig. g
l‘he latter give a firmer hold and are more readily tightened.
As shown in Fig. I, Chapter I, the vice is fixed near one
of the bench legs in order to give steadiness, but at the same
time care must be taken to see that ample room is allowed
for standing and for the free working of the arms when
filing.
MAKE SURE THIS
L!NE !S CLEAR OF
THE BENCH
Fig. I0
15
Furthermore,
the vice should be attached so that the
fixed ,jaw projects beyond the edge of the bench, as shown
in Fig. IO, otherwise you will not be able to ho!d long pieces
of material in a vertical position between the jaws unless a
packing piece is used behind the work.
VICE
SHOULD
BE
FlXED
SO THAT
THE
TOP
IS LEVEL
WITH
T’HE UNDERSIDE
OF
THE
FOREARM.
Fig.
II
If the vice is set at the correct height for working, the
top ~2 the jaws should be level with the point of the elbow
when the arm is bent, as shown in Fig. I I ; but if the bench
is of the standard height of some 3 ft. and you are not fully
grown, you may find that the vice is too high for comfortable working.
In this event, you will find it better to stand on a wooden
platform or duck-board when working, rather than to cut
short the legs of the bench ; then, in the course of time, as
you grow taller the platform dan be discarded.
16
The standard given for the height of the \:ic.c is that most
suitabie f,jr ordinary work, but for fine work the top of the
vice can be raised with advantage, in order to bring the
work nearer to the eye without the operator having to
stoop.
For this purpose, a small vice may be gripped in the
bench vice, and if one with a swivelling base can be purchased this v:ili add greatly to its usefulness. The writers
use a small “ ‘Yankee ” vice of this type? and it has proved
a great help when dealing with small M:: :k.
As has already been mentioned, a ,v-sail vice can be
clamped to the marbte slab described in the previrlls
chapter ; if a good quality vice with an efficient clamp is
obtained, it will be found that this is a most. useful appliance,
as it can be fixed where required and readily removed
when not needed.
‘I’o complete the arrangement of the bench, the bench
top should be set level with the aid of a spirit level, and if
n”cessary, thin strips of wood should be placed under the
feet for this purpose. This levelling will prevent tools from
rolling on the bench top, and may also be helpful, as we
shall see later, when using the hand drill in the horizontal
positicil.
In order to carry out the ordinary workshop
operations of filing, drilling, screw threading and soldering,
the appropriate
hand tools will be required ; these,
amongst others, will be first described, leaving an account
of their practical use until later.
Clearly, it will be possible to describe only a few of the
tools in each class, and the reader is, therefore, advised to
consult toot catalogues to make himself familiar with the
large variety of types available.
Much useful information
can also be gained by reading toolmakers’ advertisements
and by visiting the stands at exhibitions where tools are
displayed.
Files. Files are named according to their length, shape,
and the coarseness of their teeth. For filing a piece of
material to size, where a considerable amount of metal has
iiand Tools.
to be removed, a to-in. hastard-cut hand file would in. many
instances be found suitable; This means that the blade of
the file, exclusive of the pointed tang, is IO in. in length.
Bastard-cut signifies that the file has rather co~arse teeth
for taking a heavy cut ; the other grades of teeth in
co’ mon use are second-cut, smooth and dead smooth. A
1. ..1 file is one which, as illustrated in Fig. IDA, has a flat
parailel biade with a. smooth or safe-edge along one side
for use when filing against shoulders.
Other shapes of files in general use are the flat, square,
triangular, round and half-round, as depicted in Fig. 12
B, c, D and E respectively.
HAND FILE
FLAT
0
SQUARE
OR
HALF
Fig.
TRIANGULAR
ROUND
12
IS
In addition to these forms, there are many varieties
intended for special purposes and less commonly used ;
these are usually illustrated in tool merchants’ catalogues,
and further information about them and about i3es in
general can be found in “The Amateur’s Workshop,”
(Argus Books Ltd.), where the subject is fully discussed.
Before a file is put into use, it is essential that it should
be fitted with a handle, both to enable proper guidance to
be given to the blade when filing and alno to protect the
hand from damage by the pointed tang. For this purpose,
the file is secured just below the shoulder of the tang
between clams in the vice, and the handle is driven home
with light blows frotn a wooden or raw-hide mallet ; if a
mallet is not available, a piece of wood should be held
against
GiC- hidic
and struck with a hammer.
It is important that a handle large enough to give a
comfortable hand-hold should be fitted, and in addition,
t.he handle must be driven on so that it lies in a straight
line with the blade of the file, as shown in Fig. 13.
Always buy your files from a reputable tool merchant,
for then you will avoid getting poor quality tools that will
give you little satisfaction.
The length of the filej you should buy will depend largely
on the size of the work to be dealt with, and if you keep
adding to your stock as I-equired, rather than buying a
large number of files at the outset, in time you will acquire
a good selection suitable for all ordinary purposes.
For cutting brass and similar ;&oys, the file must be
quite sharp or it, will tenci merely to skid over the surfixe
of the work ; a file that has been used to file steel will :not
cut brass as it should, but, on the other hand, a file used on
brass will be perfectly satisfactory for filing steel.
To get satisfactory results, therefbre, either the files can
at first be used solely for brass and then given over to steel,
or a duplicate set of files can be bought in the first instance,
or, as a further alternative and as a measure of economy,
one side of the file can be marked with yellow paint
indicating that it is to be reserved for use only on brass,
19
and the other’ side is then kept for filing steel.
Saws. For sawing met& -a tool termed a hacksaw is
used ; this consists of a frame to hold and strain the narrow
saw blade which is furnished with teeth after the manner of
a wood saw.
-3
RIGHT
WRONG
tang of file bent
handle askew
handle too small
WRONG
Fig. 13
As this tool is used almost exclusively for cutting up all
the materials used in the small workshop, it is important
that it should be of good construction,
and that blades
suitable for this purpose should be available.
Although a hacksaw frame adjustable for various lengths
of blades is shown in Fig. 14, on the whole I would recomend a simple non-adju.stable
pattern to take IO in.
(254 m.m.) blades; for not only is the latter type cheaper,
20
but the short blades used are more readily kept on a
straight path when sawing and are not so easily broken.
As in the case of files, a coarse t,ooth is used for the rapid
cutting of heavy, material, and a blade of fine tooth pitch
is more suitable for small work ; moreover, a blade that
has been used on steel will not readily cut brass.
If we are to use the right blade for the job, two courses
are open to us : either to chamge the blade as required, or
to keep sever-al frames fitted with different types of blades.
The former course is apt to be tiresome and often results
in using any blade that happens to be in the frame, although
it is unsuitable for the work in hand and may have its
Fig. 11
teeth broken in the attempt.
If, on the other hand, the
simple type of frame recommended is used, several frames
can be bought quite cheaply and, when used with the
correct blades- for the work, the teeth will not be damaged
a.nd better work and a considerable saving in saw blades
will result.
If much heavy sawing has to be undertaken, there is no
reason why a large or an adjustable frame fitted with a
1o-in. blade should not be kept for this purpose. “ Eclipse ”
hacksaw frames a.re available in many patterns suitable for
use in the small workshop.
Saw blades for these frames are made with teeth ranging
from 14 to 32 per inch. These blades can also be obtained
hardened throughout, or with only the teeth hardened and
the backs of the blades left soft ; the latter are recommended
for th,e use of the beginner as they are much less easily
broken if the blade is inadvertently bent when sawing.
The Eclipse
light pattern saw frame, illustrated in
21
Fig. 15, holds narrow 6-in. blades with fine teeth. This
little saw will be found invaluable in the workshop for all
kinds of small ~work,
Fig. 15
The small saw shown in Fig. 16 is made with a stiff back
of either brass or steel which is folded over the blade and
gives it support throughout its length, The blade, with its
tine teeth, is useful for slotting the heads of small screws and
also for cutting thin tubing and slitting sheet metal.
L
.._
~.
Fig.
I
16
The piercing saw illustrated in Fig. 17 is in many
respects similar to the ordinary fretsaw and, as will be seen,
the tension of the blade is adjusted by setting the frame and
springing it while the blade is clamped in place.
The s-in. b!ades are made in various widths; the narrower
Fig. 17
22
are :zed, as will be described later, for cutting internal holes
ano -!i!apes in metal sheet and plate, whilst the broader
blades are more suitable for slitting and cutting off light
sections of material.
/
Fig.
18
The familiar fretsaw of the pattern shown in Fig. 18 will
be found useful for cutting sheet metal, for the great depth
of the throat enables large sheets to be dealt with or patterns
to be cut out as in ordinary fretwork. Special blades made
for cutting metal should be used ; these have a very rapid
cutting action, and, if reasonable care is taken, they are not
so easily broken as might be supposed.
Another special form of hacksaw is the Abrafile, shown in
Fig. rg ; this frame carries a blade of circular section,
somewhat like a slender round file, which can be threaded
through a hole in the work and then used to cut out a larger
hole or any other pattern desired.
Hand Drills.
We are here concerned only with hand
drills, for power-driven drilling machines as well as the
methods used in operating them will be described in the
Part Two’ of this book.
Fig.
rg
The light type of single-geared hand drill shown in
Fig. 20 is fitted with a small chuck that will usually hold
drills up to & in. in diameter. The
heavier pattern drill, illustrated
in Fig. 21, is termed a breast
drill, as it has a curved plate at
its upper end against which the
chest is pressed during drilling,
thus leaving the hands fret= to
work and guide the tool.
Fig.
20
24
In this case, a larger chuck capable of holding up to
h in. is fitted, and an easily-engaged
two-speed gear is
incorporated in the machine. It will also be seen th2.t the
operating handle can be adjusted to give greater leverage
when drilling large holes with the slow-speed gear engaged.
Drilis As to the actual drills themselves, twist drills will
be found to cut more easily than other types, and, in addition
if care is taken when drilling, holes equal to the nominal
size of the drill can be bored with considerable accuracy.
For drilling sheet metal, the straight-flute type of drill is
recommended ; these drills are similar to twist drills except
that the flutes are straight instead of being formed on a spiral
path.
It should again be stressed that drills of good quality will
prove the most satisfactory, and these can be bought either
in sets or as individual drills, according t,3 requirements.
ne disadvantage, perhaps, of these drills, when used in
the small workshop, is that owing to their special form
they are not readily resharpened
with that deFee
of
accuracy which is essential for doing good work. You may,
therefore, have to ask a friend who has a grinding device
to do this work for you.
The classification of twist drills up to 6 in. diameter is as
folll,ows :Number sites.
From No. 80 (0.0135 in. diam.) to No. I (0.2280 in.
diam.), advancing in steps of a few thousandths of an
inch.
Fractional Inch sires.
From 1/64 in. (0.0156 in. diam.) to 4 in. diam., advancing
by 1164 in.
Letter sizes.
From A (0.2340
in. diam.) to Z (0.4130
in. diam.),
advancing in steps of several thousandths of an inch.
Metric sites.
Many readers will be aware that the metric measurement
system is in the process of universal adoption. It follows
therefore that the three classes of drill mentioned will be
25
phased out in course of time. Meanwhile, drill manufacturers have been increasing the range of metric sizes they
produce. The sizes available are now very finely graduated,
as may be inferred from an inspection of the tables at the
end of the book.
Screw-Threading Tackle. Screw threads are cut by hand by
means of taps and dies. The tap is screwed into a hole
drilled to the correct tapping size, as it is termed, to form
an internal thread, and the die is screwed on to round
material, again of the correct diameter, to cut an external
thread ; with the result tha. the two parts so threaded can
be screwed together, as is seen in the case ofa bolt and its nut.
Taps and Dies. These are referred to both as to the outside
diameter of the work they are intended to thread, and to
the pitch or number of threads per inch, written t.p.i., that
they cut.
The pitch of a thread is the distance measured between
two of its crests, so that when a thread is described as 16
t.p.i. it means that the dismnce from the top of one thread
to the top of the next is +u in., and it is said to be of & in.
pitch.
In addition, the shape of the actual thread itself is always
of some standard form, such as the well-known Whitworth
thread ; but we need not here go further into this, except
to point out that nuts and bolts used together must have the
same form of thread, as well as being of the same diameter
and pitch.
The question of the form of the thread and the size of
the tapping hole required will be dealt with in a later
chapter, when the actual screw threading operations are
described.
When buying screwing tackle, you must decide what
standard of thread pitch will best suit the work you have
to do.
For wireless components and other small equipment of
this sort, the British Association, or B.A. standard of pitches
and diameters is generally used, and this will also be found
suitable for model engineering and other similar work.
26
4.
B.A. sizes are denoted by numbers, the largest, No. o,
being rather iess than 4 in. in diameter and the smallest
you will probably need, No. IO, has a diameter of a little
more than & in.
To begin with, you will probably find that the alternate
sizes from No. o to No. IO will be all that you need, and
any intermediate sizes can then be bought later as required.
The standard Whitworth sizes above & in. have too
coarse a pitch for small work such as model engineering.
The British Standard Fine, or B.S.F. sizes, although
of
finer pitch, are still rather coarse for small engineering and
instrument. work.
The Standard Brass thread of 26 t.p.i. in all sizes up to
* in., and more, is suitable for threading the larger components used in model engineering work.
To meet the special needs of the model maker, The
Model Engineer many years ago very wisely introduced a
standard of 40 t.p.i. for all sizes up to & in. in diameter, and
having 32 t.p.i. for & in. and 3 in., and 26 t.p.i. for & in.
and 4 in.
Following this, taps and dies of 40 t.p.i. are now available
in all sizes up to 3 in. or more. These fine threads are
especially useful to the model engineer for threading thinwalled tubes and piping.
From what has been said it will be apparent That fine
threads are tending to replace the older forms of coarse
threads for small engineering work, and this has been made
possible by the accurate methods now used in making taps
and dies which produce a well-cut thread that gives a
secure hold.
When buying screwing equipment,
it is also most
important
to choose the best quality obtainable,
and
moreover, it is a good plan to buy a set of tackle, provided
that ,it is exactly what is required, for then a box will be
included for storing the equipment and protecting it from
damage.
Taps. In the smaller sizes two taps are usually provided
for each size, that is to say a taper tap for starting the
27
threading operation and a second tap for completing the
thread.
A third form known as a plug or bottoming tap is used,
particularly in the larger sizes, for cutting the thread to
the bottom of a hole. These three forms of taps are illustrated in Fig. 22.
Dies.
For all small work
these are now made of the circular pattern shown in Fig. 23,
and it will be seen that the die
is split so that it can be
adjusted for wear, either by
means of a setting screw or
teper
second
Pb
Fig. 22
by being pinched in the die
holder.
Tap and Die Holders. If you buy a set of screwing tackle,
a tap holder and a die holder will probably be included.
The tap holder illustrated in Fig. 23 is adjustable to fit
taps of different sizes, and when secured to the squared
portion of the tap’s shank it is used as a
turning wrench.
When applied to small taps, this type of
wrench may be found rather difficult to use
and somewhat cumbersome, and in that case
the holders shown in Figs. 25 and 26 may be
more convenient.
Fig. 23
These holders have a two-jaw chuck which
is contracted by means of the knurled sleeve to grip the
squared end of the tap.
The die holder depicted in Fig. 27 is provided with a
set screw for holding the circular die in place, and some
patterns of die holders, and by far the most useful, have
guides for holding the die truly in line with the work. A
Fig.
24
28
holder of this type is shown in Fig. 28, and it will be seen
that below the die is a housing in which a circu!ar guide
collet is retained by means of a set screw. Needless to say,
a collet of the correct size must be used to fit the work being
threaded, but there is no difficulty in this, as sets of collets
are supplied with die holders
of this type.
standard
American
Some
die holders are of this pattern,
but at present some. difficulty
may be experienced in obtaining these tools.
Another form of die collet
is shown in Fig. 2y ; here,
the die fits into a housing
which itself forms the collet or guide for the work.
Shears. For cutting sheet metal, the tool generally used
Fig. 26
is the hand shears or tinman’s snips, and both the straight
and the curved pattern are illustrated in Fig. 30.
The straight form is used for all straight-line work and
for cutting out large diameter circles, whilst the curved
pattern is suitable for cutti-rg out circles of small diameter
and for all internal curved work.
Fig.
27
As in the case of ordinary scissors, only thin material. can
be cut owing to the limited leverage available.
Where
thick ~sheet metal has to be dealt with, greater cutting
29
pressure is required, and for this work a bench shearing
machine of the type illustrated in Fig. 3 I is generally used.
Fig. 29 (left)
di:
As will be seen in the drawing, the system of link.age
employed provides great leverage and this is further
increased by using a long handle to work the machine.
Although this machine is undoubtedly useful in the smail
workshop, its purchase would seem hardly justified unless
much sheet metal cutting is undertaken.
STRA!GHT
CURVED
Fig. 30
30
\Vhen dealing with the use of the hand shears in a later
chapter, some ways of increasing the cutting power of the
tool and making it more easily operated will be described.
n
fig.
31
The four forms of metal-cutting
chisels in
common use, or cold chisels as they are called, are illustrated
in Fig. 32 ; and of these the flat type is often used by the
modei engineer for cutting metal in awkward places where
other tooh, such as saws and i&s, c.annot easily be brought
to bear.
The other three forms are used for specials work, that is
to say for cutting heavy metal plate and keways, forming
oil grooves in bearings, and clearing out the corners of cast
work respectively.
These chisels are usually forged from octagon tool steel
and are then hardened and tempered to enable the cutting
edges to withstand the shock of the hammer blows used to
drive the tool along the work.
In addition to this pattern, Messrs. Moore & Wright
Chisels.
31
manufacture
a range of flat rectangular section chisels,
made of a special nickel alloy steel, which have superior
cutting m-operties and are more readily resharpened when
blunted.
FLAT
CROSS
CUT
Fig.
ROUND
NOSE
DIAMOND
POINT
32
Scrapers. Although
scrapers are made in a variety of
forms adapted for different purposes and for working on
flat and curved surfaces, a single flat scraper of the pattern
illustrated in. Fig. 33 will be found sufficient for most
purposes in ,the small workshop.
The scraper is a most
Fig. 33
useful tool for removing small amounts of metal when fitting
parts together, and, unlike the file, it will readily remove
the metal in exactly the place required.
Scrapers can be bought from the tool merchant, but
mechanics usually prefer to make them from a discarded
32
flat file, as files of good quality are made from steel which
is most suitable for this purpose. So if you have a friend
who is willing to make you a scraper, so much the better.
The method of using and sharpening the scraper will be
descr,ibed in a later chapter.
Tools used for Assembling Work. Although the size of these
tools wiil, of course, vary with the character of the work
undertaken, their actual form will be substantially the same
in all cases. For assembling models and other small work,
you wili find it a good pian to keep a selection oi these stools
in a box or drawer apart, so that they are always ready for
use and do not have to be collected from various places in
the workshop.
Spanners. The open-ended type shown in Fig. 34 can be
obtained to fit all sizes of nuts from IO B.A. up to the very
largest, and their size is always denoted by the size of the
nut they are intended to fit, and not by the width apart
of the jaws.
Spanners of the open-ended pattern have the disadvantages that they are apt to slip when in use, and also they
engage with only two of the flats on the nut at a time,
whereas the types shown in the subsequent drawings make
contact with all six of the nut faces and thereby obtain a
better hold with much less liability to slip or damage the
33
nut. If a spanner slips when turning a nut, it mav cause
unsightly damage which will spoil the appearance of a
well-finished piece of work.
The spanner shown in Fig. 35 is known as a ring spanner
and is largeby employed for turning nuts which are in
frequent use, such as those on the adjustable parts of
machine tools.
Fig. 36
Messrs. Terry make useful sets in thin material of both
open-ended and ring spanners to cover the range required
for all ordinary work.
The box spanner, Fig. 36, is generally used for heavy
Fig. 37
work, but it can also be obtained in small sizes suitable for
wireless and other similar work. As will be seen, the tubular
portion is cross-drilled to take a round tommy bar to give
the necessarv leverage for turning the nut.
A more highly-finished form of box spanner is shown in
Fig. 37 ; here, the recess to receive the nut is machined
and the shank is fitted with a plastic or wooden handle.
These spanners will be found much the most useful form
for light assembiy work.
For heavier work, this type of spanner is fitted with a
metal cross-handle, as illustrated in Fig. 38, and is then
known as a T-spanner.
Where nuts have to be fully and securely tightened the
socket wrench illustrated in Figs. 3g and 43 may be used
with advantage, for both a firm hold and good leverage are
readily obtained.
34
These spanners comprise a set of sockets, which for
storing are threaded on to the turning bar and retained in
place by means of the spring detent shown on the left of
Fig. 39.
When buying spanners make sure that you select only
those of good quality and of sizes suitable for the work
you intend to do, ‘bearing in mind that you can always add
others later on as the need arises.
Screwdrivers. Three forms of screwdrivers are illustrated
in Fig. 41 ; the first is the type commonly used by the
woodkvorker ; the second is the machinist’s screwdriver
ivhich is fitted with a fluted handle to give z firm hand-hold
and is the pattern generally used by metalworkers.
The
third form is smaller in size and has a blade adapted for
turning rhe small screws used in model engineering
--.d
instrument work. LVhen using these tools, the tip of the
forefinger is placed in the recess of the swivelling top and
the handle is turned with the tips of the thumb and second
finger.
Fig. 38
Fig. 39
woodvarkers
mechanics
watchmakers
Fig.
41
36
These screwdrivers can be bought in sets to fit the screw
heads of a wide range of small screws.
It is important that not only should a screwdriver be
used that fits the screw head, but, at the same time, the tip
of the blade should be kept in good condition, so that it
does not tend to slip out of the screw’s slot and thus, perhaps,
mar the appearance of a carefully-finished piece of work.
combination
WJnd
nose
Fig.
end nips
42
Those wishing for further information
on this point
should consult “ Sharpening Small Tools,” published by
Argus Books Ltd.
Pliers. Inspection of a teal merchant’s catalogue w!.ll
show the great variety of pliers made for general use and
also for special purposes. There is, however, no need to
buy a large selection of these t:ools in the first place, as a
pair of combination pliers will probably be found sufficient
I
31
for all ordinary work. ru’evertheless, a pair of round-nosed
pliers and also a pair of end- or side-cutting pliers, as
illustrated in Fig. 42, will form a useful addition to the
took kit.
When buying, it is important to select tools of good
quality, as shown by the pliers being polished all over and
having a firm but smooth-working joint ; in addition, the
jaws should be well finished, so that they meet accurately.
Formerly, parallel-ja’w pliers of American make could be
PANE
Fig. 43
obtained at any good tool store. These tools were of good
quality with a fine finish, and as they were well designed
and accurately made of high-class materials, they gave
good and long service in the hands of a careful user.
Hammers. Two patterns of hammers are shown in Fig. 43.
The ball-pane or rounded face is used in the metal
workshop for setting and rounding over the heads of rivets
and pins. For genera!. use, a hammer of some 2 lb. weight
will be suitable, whilst for light work a small hammer with
a 2 to 3 oz. head will be required.
The cross-pane hammer is mostly used in woodworking
shops where the cross-pane is essential for setting and driving
nails in awkward places.
Best quality hammers have a finely-finished and polished
head, and the shaft is made of straight-grained
hickory ;
in addition, the perfect balance can at once be detected
when the hammer is taken in the hand.
38
Pin Punches. These tools, which are usually purchased in
sets, are used for driving out pins when taking machines
and other .mechanisms to pieces. The drawing in Fig. 44
shows that the punch has a long parallel working portion
and a knurled shank to provide a good grip for the fingers.
Fig. 44
For ordinary soldering operations
qtiite simple equipment will suffice. This consists of one
or more soldering irons with a means of heating them, and,
in addition, a supply of solder ax-id fluxing material.
Soldering
Equipment.
Fig. 45
A soldering iron, as shown in Fig. 45, consists of a copper
bit, as it is termed, riveted to an iron shaft which is fitted
with a wooden handle. T’-llL bit illustrated in Fig. 45A is
pyramidal in form, and that in Fig. 45B is hatchet-shaped
for use when soldering seams and for penetrating
into
awkward places.
Soldering irons are made in various weights, but for
general work a bit weighing from 6 to 12 oz. will be found
suitable.
Gas, when available, may be used with a Bunsen burner
or gas ring for heating the iron, which in the former case
39
can be supported on an ordinary laboratory tripod, as
shown in Fig. 46.
Self-contained
gas-heated so1derin.g irons can also be
obtained, and although this is a convenient method of
heating the iron, the attached gas pipe may be found rather
a nuisance.
Fig. 46
When a coal or coke fire is used for heating, the iron is
apt to become coated with ash ; also, it is more difficult to
control the heat and this may result in the bit being overheated.
As an alternative to heating the bit wieh a gas burner, an
electrically-heated
soldering iron may be used.
This has many advantages, for the iron is then kept clean
and, as a result of the special manner in which the iron is
wound, there is little danger of overheating the bit.
The question of solders and fluxes will be dealt with in
a later chapter, where soldering operations will also be
described.
40
Oilstones. For sharpening tools, such as chisels, scrapers
and pointed tools, in addition to any woodworking tools
b-ou may USC:, you will need an oilstone or, perhaps one
stone for rapid cutting and another for giving the final fine
finish to the cutting edge.
Oilstoncs are of two kinds : the artificially produced
carborundum
stone, and the natural form, such as the
Arkansx \~vhichconsists of almost pure quartz.
F:K restoring the damaged edge of ;a. tool, an artificial
s;tc,tlc. \vili rerno\ve the unwanted metal quickly ; and it will
Ix: found that the India stones manufactured by MesSrs.
Nor~or~ ;!brasives are not only excellent for this purpose,
but their hard texture prevents them from becoming
unevenly worn or scored if reasonabie care is taken.
To produce a highly-linisfied cutting edge, the sharpening
operation is usually completed on a natural stone like an
Arkitnsas or U’nshita. The former is ra.,ler expensive, but
as it is extremely hard it will resist wear and should last
almost indefinitely.
If a soft stone is purchased, it will be
found that the surface is easily scored and is apt to wear
unevenly, so that in time it becomes unfit for sharpening
mis accurately.
It is best to buy bench stones of the standard size, that
is to say they should be 8 ih. long, 2 in. wide and I in thick.
Smaller stones usually make tool sharpening more difficnlt, especially in the case of the larger tools, such as
scrapers, \.vood chisels and plane blades, which usually have
a place in the small w~orkshop.
Read the makers instructions caref‘ully and carry out
their recommendations
as to upkeep, in order to ensure
good and lasting service from your oilstones, for the quality
of your work may in part depend on their efficiency.
Those \v~Y)require further information about the selection and use of oilstones should consult “ Sharpening
Small Tools,” published by Argus Books Ltd.
CHAPTER
THREE
Callipers Rulers Micrometers
Depth
Gauge-The
Protractor-Drill
Gauge - Marking-out-Equipment
required-Marking-out
Sheet Metal Work
-Witness
Lines - Marking-out
Solid
Objects-Marking-out
a Bearing Bracket
-Marking-out
the Centre of a Shaftseading Machine Drawings.
1~ all mechanical
xvork, lvhere parts are machined or
formed with hand tools to fit together, some means of
making measurements will be almost essential both for
maintaining
accuracy and for sating
~1~~~~~ FQR loss of time.
For example, if we have to fit a shaft
to a small bearing, we could go on
gradually removing metal from the shaft until it fitted in
place, but clearly a better method would be to measure the
bore of the bearing and then to machine the shaft to exactly
this diameter, less, of course, a small allowance to give h
working clearance.
How then are we to make these exact measurements?
In commercial practice the bearing may be made in one
factory and the shaft in another, yet when the parts are
assembled in a third factory they are found to fit together
perfectly.
This result is obtained by the use of very accurate and
expensive gauges, but these methods are hardly suited to
the type of work usually undertaken in the srnall workshop,
where a single model only may be constructed and the
parts are then made imd fitted together individually.
Caliipers. Let us again consider the shaft and its bearing.
What we are really concerned with here is the diameter
of the shaft relative to the bore of the bearing and quite
41
42
irrespective of the actual size of the parts measured in
inches.
The bore of the bearing can be gauged by means of the
inside callipers shown in Fig. 47. The legs are set with the
fingers to make conmct with the bore and the final fine
adjustment is made by tapping the callipers on a piece of
wood. To oper the legs, the callipers are held with the
Fig.
47
points uppermost and thejointed end
whilst to close the callipers the iegs
struck against the wood.
Th.e adjustment is continued until
is felt as the tips of the calliper legs
in the bore.
Fig.
is tapped on the wood,
themselves are lightly
a slight resistance on2y
are moved to and fire
48
The next step is to set the outside callipers, shown in
Fig. 48, exactly to the inside callipers, using the method of
setting already described, but great care must be taken
when doing this not to upset the adjustment of the inside
callipers.
The points of both callipers must be held quite square to
each other when testing the setting, as shown in Fig. 49,
otherwise a false reading will be obtained ; in addition,
the process will be made easier if the points of both calipers
are rested on a flat surface when testing the setting.
43
The outside callipers can now be used as a gauge to
determine the diameter of the shaft required to make it a
sliding fit in its bearing, and, moreover, it will be apparent
that only simple tools are needed when this method is used.
RS
Fig. 49
As to the accuracy of the method, the writer found that,
when making a series of measurements,
errors of one
thousandth of an inch could quite readily be detected, but
some practice will be needed before this degree of accuracy
of working is acquired.
The work of setting the callipers will be made easier if
the screw-adjustable pattern is used ; these are illustrated
in toolmakers’ catalogues and also in Fig. 56, where the
dividers of this type are illustrated.
If desired, the setting of the inside callipers can be
measured against a rule and the outside callipers then
adjusted to the same mar~k on the rule, but in this case
quite large errors are almos* sure to arise and this method
is not recommended except for making rough measurements.
As an alternative method, instead of the inside callipers,
a piece of metal rod can be used to gauge the bore, and the
outside callipers are then set to this.
44
For this purpose, th,e shank of a drill which exactly fits
the bore can be used, or a tapered cotter pin such as is used
for assembling machinery will make a useful gauge. The
latter can be inserted in the bore of the bearing and marked
with a pencil at the line of contact, as illustrated in Fig. 50 ;
the outside callipers, when set on the gauge piece just short
of the pencil mark, can then be used for determining the
-size of the shaft required to fit the bore.
The Rule. So far, we hav-e considered only the relative
sizes of components without giving their actual size such
as we could state numerically, or could show in a mechanical
drawing.
When actual linear dimensions are required. they can be
measured, although not really accurately, by means of a
rule of the pattern familiar to all workers.
These rules are made of steel and the graduations are
machine engraved to ensure the accuracy of the markings.
Tempered steel rules are best, as they resist wear and are
not so’liable to become rusted from handling.
45
X large rule of I ft. or 6 in. in length will be required,
and in addition, a short +n. or 4-in. rule will be found
handy for small work.
Rules are generally made with several sets of graduations
ranting from ,& in. to I /IOO in., and although the latter
fine divisions may be useful at times, they are difficult to
read accurately and confusion may easily arise.
Micrometers. For the accurate measurement oflength in
the workshop, that is to say in terms of a thousandth of an
inch, it is usual to employ a micrometer, which ronsists’of
a steel bow fitted with a fine measuring screw ; or a sliding
gauge with a vernier attachmem
may be used for this
purpose.
These rather expensive instruments are usually graduated
to read in thousandths of an inch.
The micrometer of the form in general use has a range of
only 1 in., and separate instruments a.re required for making
inside and outside measurements, as well as for determining
the depth of holes and dimensions of height.
The vernier slide gauge, on the other hand, has a long
graduated scale which enables a single instrument to make
both inside and outside measurements up to a length of
12 in. or more.
Those who, at this point, require further information
about
these toois should refer to “ The Amateur’s
Workshop,”
published
by Argus Books
Ltd.,
whilst
particulars of the ;patterns in general use will be found in
toolmakers’ catalogues.
The Depth Gauge. The gairge shown in Fig. 5 I is used for
measuring the depth of a hole or shoulder, as indicated by
the rule when the base piece is in contact with the surface
of the work.
The narrow rule fitted is usually graduated in 1164 in.
on one side and in .I /I oo in. on the other.
To use the gauge, the base pieke is pressed against the
work and the rule is pushed downwards until it meets the
bottom of the hole whose depth is being measured ;
the clamping screw is then tightened to enable the gauge
46
to be handled
without fear of upsetting its adjustment.
The Protractor.
This instrument, which is illustrated in
Fig. 52,~ is used for measuring and marking-out angles.
The rectangular stock or base is graduated in degrees from
o to rDo deg. at either end.
When *he protractor
has been set as required, the
movable blade is locked to the stock by tightening the
central clamping screw.
Fig.
The Drill
52
Gauge. As will be seen in Fig. 53, one form of
this gauge is made with a series of holes ranging from & in.
to 4 in. in diameter i; ad advancing in steps of 1164 in.
These gauges are accurately made of hardened steel, and,
as far as the hole sizes allow, can be used for determining
the diameter of shafts and other components in addition
to their normal use for gauging the size of drills.
Resides the fractional inch gauge ii.lustrated, a similar
pattswn
,-an
ha
I.11..
_U..
“\r obtained
-.-1LL
W~LII‘-noies indicating the diameters
4-J
of the number-size drills from No. I to No. 60, that is to say
from 0.040 in. to 0.228
in., advancing in steps of a few
thousandths of an inch. These drill gauges are also marked
with the decimal inch equivalents of the drill sizes.
In addition to its use for
measuring the size of drills and
0
I/l6
other small components,
this
8
gauge, as will be described
s/64
later, can be employed for
0
determining
the size of the
NJ2
tapping holes required for small
Q
taps used to cut screw threads.
7164
Marking-out
8
arking-out.
118
is, briefly, the process of draw8
ing lines on the surface of the
Q/64
work to indicate its finished
size and, at the same time,
marking
the centres of any
drill holes required, and scribII164
IQ/64
ing reference lines as an aid
0
3115
work
for
the
setting
to‘
0
machining.
I3164
Marking-out
flat work or
sheet metal is very much the
same as making a mechanical
drawing,
and, here, at any
15164
rate, you will be able to make
use of any geometry you have
learnt.
Before
any
marking - out
Fig. 53
work can be undertaken
a
few simple tools and materials will be needed, and these
will now be described.
In the first place, it is essentials that the marking-out lines
drawn should be clearly visible to act as a guide when later
the work is being formed to shape.
If the material used is sheet copperor brass, the lines will
48
probably show up clearly, bwc in the case of steel the surface
will have to be painted with a marking fluid to ensure this.
B!.ue-colccrrd,
quick-drying, marking fluid can usually
‘be purchased from the tool merchant, but if there is any
difficulty about this, some French polish or spirit varnish
with a little blue dye, such as methylene blue, added will
make a good substitute.
Fig.
54
For scratching the lines on the surface of the work a
scriber, as shown in Fig. 54: is used ; this tool has a
hardcued-steel sharp point and a knuried handle to give a
good finger-hold.
To cover the usual range of work when drawing lines at
right angles to a base line, one or more squares, as illustrated
ir;Fig.
‘,5, will be required.
A 6-in. square shouid be
ample for larger work : a 3-in.
square Wili be found most
generally useful : and it is an
advantage
to have a I-in.
squxe for small work and for
checking
the squareness
of
Messrs.
edges when filing.
Moore & Wright make a &ii
squares
of accurate
range
suitable for use in the sn,all
workshop.
For laying off distances and
for scribing circles a pair of
dividers is essential.
The pattern illustrated in Fig. 56 is
adjustable by means of a screw
and is greatly superior to the
plain type. To set the dividers,
Fig. 55
49
one point is placed in an inch mark. on the rule and l~he
other point: is then adjusted until it lies exactly in ::he
graduation. line required.
When lines have to be scribed at a fixed distance f&iii
the edge 0;‘ the work, thejentnq: callipers shown in Fig. 57 are
used.
The legs are set to the required distance apart by placing
the point in the required graduation on the rule, and the
ot,her leg is then pressed inwards until it makes contact
with the end of the rule.
To use the callipers, the curved leg is pressed against the
edge of the work and the sharp point is used as a scriber,
but care must be taken to maintain the callipers at right
Fig.
57
angles to the work, otherwise the line marked will not be
at the correct distance from the base throughout.
When the point of !mtersection of two scribed lines is used
to denote a drilling ,centre, this point is marked with a
fine-pointed centre puncI~, as illustrated in Fig. $3.
QO”
POINT
J
60.’
Fig.
58
POINT
As an aid to locating the punch exactly at the required
point, a magnifying glass can be used with advantage, and
the punch, while held vertically, is then struck a light but
firm blo-w with a smaii hammer.
As a practical example of
Marking-out Sheet Metal Work.
marking-out let us take the sheet metal packing-piece or
-
f
cover plate shown in the drawins in Fig. 59 ; its thickness
does not matter for our purpose, .IS we are concerned only
with its shape as seen from above.
The drawing represents a square plate with rounded
corners and having four holes equally spaced at a given
distance apart.
The drawing also shows the exact dimensions required,
that is to say the len@h and breadth of the plate, the position and size of the holes, and the radius of the rounded
corners.
51
To make a start, take a suitable piece of flat sheet metal
and with a rule and scriber draw a straight line along one
edge, as indicated in Fig. 60.
The edge of the sheet is then cut and filed exactly to this
line as will be described in detail in the next chapter. The
straight edge so formed is called the datum edge, as from it
the dimensions of the work are marked-out in accordance
with the drawing.
Apply the square to the datum edge and scribe a line,
A@ Fig. 61, at right angles to it to represent one side of
the square ; then set the dividers to exactly 2 in. and scribe
an arc of a circle, CDE, from a point on this line.
Apply the square again to the datum edge and draw a
vertical line, FG, through the extreme edge of the arc to
mark the opposite side of the square.
Set the jenny calipers to exactly 2 in., and with the
curved leg against the datum edge mark off the line, GE,
to complete the square. The next step is to mark the lines
HJ and KL with the jenny set to Q in. Set the dividers to
% in., and with one point placed at the intersection of the
cnes FG and HJ mark off the distance HM, and also LN,
in a similar manner.
With the square against the datum line, draw the two
vertical lines OP and QR through the points M and N
respectively.
Set the dividers to 14 in., and fi-om M and N scribe arcs
to cut OP and QR at S and T. Mark the points M, N, S
and T with the centre punch to denote the drilling centres
of the four holes.
When doing this the centre punch must be held exactly
vertical, otherwise the centres will be drawn over to one
side and the holes will be drilled out of their correct position.
The appearance of the work will now be essentially as
shown in Fig. 62, and it only remains to comp!ete the
marking-out in the following manner. Set the drvrders to
Q in. and mark off the radius of each corner as shown ;
then reset the dividers to & in. and scribe the dimension
lines of the four holes. The final siep is to scribe and
‘WEE
T
METAL
i
DATUM
LINE
Fig.
60
Tl
C -b
L-
aI
i Q
oSf
--L--
-
I
DATUM ‘LINE
Fig. 61
-~
-1 -
’
I
I
’
7
53
punch-mark
what are described
as the witness lines.
Witness Lines. When small holes are being drilled, the
circle scribed to show the diameter of the hole will clearly
indicate if the drill at starting is at all off-centre, but in the
case of larger holes, one or more witness or guide circle:
should be scribed within this circle to make any error of
drilling more readily apparent as the work proceeds.
W!TNESS
DRILL
HOLE
LINE
A
Fig. 62
A witness line, outside the circle indicating the hole
diameter, as shown in Fi,g. 62, may be found useful as a
check on the final accuracy of the drilled hole, and will
also serve as a guide should the position of the hole have to
be corrected later by filing.
To make sure that these lines do not become obliterated
until they have served their purpose, they may be lightly
marked with a centre punch as shown in the drawing.
When marking-out a piece of work in which holes of
various diameters have to be drilled, you will find that
mistakes can be avoided it the size of each hole is marked
opposite to it with the scri’ber.
54
The work is now marked-out in accordance with the
drawing and is ready for drilling and cutting to shape.
Marking-out Solid Objects.
So far, we have considered
only flat work, but when we come to marking-out solid
objects some additional equipment will be required.
SCRIBERMAY BE INSERTEO
HEREFOR wo
TO THE BASE
Fig. 63
55
SURFACE
ANGLE/
Fig. 64
In the first place, a flat surface on which the work can
stand must be provided, and for this purpose a surface
plate, as illustrated in Fig. 64, is generally used, but a sheet
of plate glass makes a satisfactory substitute.
The surface plate is a heavy -rigid iron casting whose
upper surface has been machined and finally hand-scraped
to a high degree of flatness, but a machined casting will be
sufficiently accurate for ordinary marking-out purposes and
has the advantage of being very much cheaper.
For scribmg lines on the work at a given height above
the base, the surface gauge is used ~instead of the jenny
callipers.
The surface gauge made by Messrs. Brown & Sharpe is
illustrated ‘in Fig. 63, and it will be seen that the pointed
scriber can be set in any position required and also adjusted
for height by sliding on the pillar. In addition, the height
of the scriber point can be set by swinging the pillar,itself,
wb.ilst the final exact setting is made by means of the fine
adjustment screw shown,
The retractable pegs fitted to the base can be pushed
downwards toi guide the gauge along a reference surface,
such as the m,achined edges of the surface plate.
The height of the scriber point is set against a rule, held
truly vertical to the surface of the marking-out table either
by being pressed against a r-ctangular.block
or angle plate,
Fig. 64, or by being clamped in a special rule holder or stand.
56
Full directions for making a simple but efficient rule
stand are given in Chapter Five.
When cylindrical work has to be marked-out on the
surface plate, it is usually held in position by means of a
Piblock, as shown in Fig. 69, or two similar blocks may be
used to support long work.
SURFACE
PLATE
Fig. 65
To denote drilling centres, as in the case of sheet material,
two lines are scribed at right angles, and to facilitate this,
the work, where it will not stand firmly and evenly of its
own accord on the surface plate, may be secured to an a.ngle
plate as shown in Fig. 64.
Marking-out
a Bearing Bracket.
Now that the tool
equipment required has been briefly described, let us take the
bracket shown in I’ig. 65 as a simple but practical example
of marking-out a solid object on the surface plate with the
aid of the surface guage.
The problem here is to mark-out the boss so that it can
s7
be drilled and bored to receive a bearing bush or liner ;
the centre lin,e of the bearing must be exactly 2 in above
the base line in order that the shaft it carries will be truly
aligned in the machine to which the bracket is attached.
In the first place, the under surface of the foot piece must
be made flat, as will be described in the next chapter, so
that it will stand on the surface plate without rocking.
This surface, corresponding to the datum edge of the
work in the previous example, is called the datum surface,
Fig. 66
and it is on this that the bracket is finally bolted in place in
the machine of which it forms part.
Accordingly, the centre line of the bearing is scribed 2 in.
from the datum surface.
After the face of the boss has been painted with marking
fluid, the casting and the surface gauge are placed on the
surface plate as illustrated in Fig. 65.
The next step is to set the point of the scriber exactiy
2 in. above the base line, as shown in Fig. 66. This is done
by holding the rule in a truly .vertical position against an
angle plate, or by clamping it in a rule holder, and then
setting the scriber point to the z-in. mark by using the fine
adjustment screw for the final setting.
When set, the scriber should lie horizontally, or nearly
so, for in that position not only will it mark better, but it
will be less liable to deflection when meeting any irregularities on the surface of the work.
E
Now, grasp the base of the surface gauge and move the
scriber point right across the surface of the boss so that a
clear, even line is marked ; when doing this, the scriber
should be allowed to trail somewhat, otherwise it is apt to
d’1g into the work and form an irregular marking.
Fig. 67
To scribe the cross-centre line, the casting is placed on
its side as shown in Fig. 67. The diameter of the boss was
found to be I in., and its outer diameter lay g in. from the
edge of the casting ; the scriber point is, therefore, set
to I in. a,yainst the rule, and the cross-line is scribed
across the- centre of
the boss.
As in the case of
the sheet metal component already refercentre
red
to
a
punch-mark
is made
at the intersection of
two cross-lines,
the
and from this centre
both t:he bore diameter
and the inner witness
WlTrjESS LINE
lines arc scribed -with
the dividers.
Fig. 68
L
59
The marking-out is completed by dotting the circumferences of thesr two circles with the centre punch, in order
to ensure their remaining visible throughout the subsequent
machining operations.
The appearance of the finished work will then be as
depicted in Fig. 68.
Fig.
Marking-out
6g
the Centre ofa Shaft. Anoperationcommonly
required in the workshop is to mark-out the centre of a
round shaft. For this purpose, the shaft is placed in a
V-block, or in a pair of similar blocks, on the surface plate
as shown in Fig. 69.
The point of th.e scriber is set to the approximate centre
height and a short line is scribed across the centre ; the
shaft is then rotated some sixth of a revolution and a second
line is scribed ; this pro cedure is repeated until the shaft has
been completely turned.
It will be found that the marking lines now enclose a small
central space, and if the scriber point is reset to the centre
of this area, the cross-centre lines can be readily marked-out.
If the two centre lines are required to be exactly at right
angles to each other, the horizontal centre line alone is
marked with the surface gauge, and the vertical centre line
is then scribed from a square standing on the surface plate.
Those who desire further information will find the whole
subject more fully dealt with in “Marking-out
Practice”
published by .4rgus Books Ltd.
80
Machine drawings are issued
as a guide to enable workers to make mechanical parts in
the workshop.
Thwe drawings usually comprise a general arrangement
drawing giving a picture of the work as a whole, and, in
addition, detail drawings showing the form and dimensions
of the several parts.
En the general arrangement drawing the appearance of
the component is represented separately in the three planes
in space as illustrated in Fig. 70 ; that is to say the plan
view as it is seen directly from above, the front elevation
as viewed from in front, and the end elevation showing the
component as seen end-on.
Reading Machine Drawings.
!
2
mpldn
z
#
end
elevdt ion
3
-
-
H
Fig.
70
Those who are familiar with mechanical drawings are
able to combine these three drawings in the mind’s eye: as
it were, and to visualise the object as it would actually
annear : but for the benefit of those who are unable to do
61
this, the modern method of isometric projection combines
these three drawings in a single view, as see:o in Fig. 70,
which shows clearly exactly what the ob.ject is like and thus
prevents ariy mistake being made as to its real form.
Another form of drawing, whi$h is often used to show the
internal construction of mechanical work, is the sectional
drawing. These drawings are not only a great help to the
mechanic when dealing with complicated work, but they
also lessen the work of the draughtsman
by simplifying
and ,reducing the number of drawings required to show all
the details of construction and the position of the individual
parts.
A typical example of sectional drawing is given in Fig. 7 I.
which shows in section a bush inserted in a housing.
Unless otherwise indicated in the drawing, these sections
are always taken through the centre line of the component ;
and in order to make the relation of the parts clear, the bush
is hatched with a series of parallel lines, whilst the shading
lines on the housing are drawn at right angles to those on
the bush.
Conventions Used in Drawings. For the sake ofuniformity,
certain methods of drawing have been adopted and are now
62
in general use ; as a guide to their interpretation the more
common conventions are now described.
Screw Threads. In Fig. 72 the various ways of representing
both external and internal screw threads are illustrated ;
those shown at A and D are: detailed drawings of the thread
form, and the shading is added to improve the appearance
EXTERNAL
THREADS
0
A
0
6
0
C
INTERNAL
THREADS
.-.
.-.
Fig.
72
0
c
63
0d
0
b
Fig. 73
and to make the drawing suitable for reproduction in the
Press.
f the remainder, C and G are the simplest, and, as they
Fig. 74
64
take but little time to draw, this method is now largely
used in the drawing office to save valuable time.
Nuts and Bolt l-leads. These are always shown insolid form
unless a sectional view is necessary for some special reason,
and the full diameter of the nut across its corners is represented as in Fig. 73~ ; but where the nut has to be shown
at Gght angles to the former position it is drawn as in
Fig. 73B.
Germ-e 1Lines. In all drawings the centre line of each
component is shown by a chain-dotted line.
These lines are important to enable measurements of
dimensions to be taken readily. For example, the centre
lines of the cylinders of a petrol engine are drawn so that
the exact distance between the cylinders can be measured
in the workshop.
Hidden Parts. These are represented in the drawing by
broken lines as shown in Fig. 74, which depicts a bearing
bracket fitted with three inset bushes. The use of this
convention saves much work, as otherwise several drawings
might be required to show the exact relation of the parts.
0
b
Fig. 75
65
0
b
-
I~
Fig.
squat-es
76
shown in Fig. 75, these are indicated in
inches, and parts of an inch, by figures between arrows
pointing to the lines which show the limits referred to.
Where space is restricted, the position of the arrows and
figures may be arra.nged as illustrated in Figs. 75A and 75B.
Fiat Surfaces. When a flat surface is formed on a shaft
this is indicated as shown in Fig. 76~, and in addition, the
surface of the flat is sometimes drawn with the diagonals,
as when a square formed on a shaft is denoted in the manner
illustrated in Fig. 75~.
Dimensions.
As
CHAP'fER
FOUR
Filing-PinningDraw
FilingFiling
Alumini~!m-Scraping-SawingMetalMarking-out
the Work-Using
the Hacksaw-sawing
Curves-Cutting
Metal,Cold Chisels-Hand-Drills-The
Drilling
Operation-Polishing-Reaming-Screw
Threading-Cutting
Threads-Soldering
-Hardening
and Tempering.
in the workshop is the first essential, and is
the basis of accuracy and efficiency. Without it good work
can only be produced with difficulty, if at all. A .clean
workshop inspires good work ; a clean
machine
and a clean work bench
D
produce it.” These words are taken
from the Introduction
to a handbook
on engineering workshop practice published in the early
part of the recent war ; they were intended for the host
of inexperienced but willing people who were, at the time,
flocking into our munition factories.
Nevertheless, this good advice has lost none of its force
even today, and its import should be borne in mind by
amateur and professional worker alike.
Beginners should cultivate the right way-of working from
the start, so that in time the maintenance of tidiness and
cleanliness in the workshop becomes a fixed habit.
As it is almost impossible’to keep the wooden Emch top
perfectly clean while working, spread newspaper where you
put down your work or fine tools, and change it frequently
so that you can be sure that it is always clean and free from
filings or emery dust. Keep some trays or old saucers handy
in which to put small parts when taking work to pieces.
Filing. I have already described the forms of files in
common use and have pointed out the necessit~y of fitting
a proper handle to the file. Further the importance of
“
@LEAKLINES
66
having the vice firmly secured to a rigid part of the bench
has been stressed.
The question of usir~g different files for various types of
metals has also been d&lt with.
When it comes to the actual filing operation, the method
used varies somewhat for heavy or light filing.
Mrhen a bastard-cut
file, for example, is used for the
quick removal of a large amount of metal, not only mwst
considerable downward pressure be exerted to keep the
file in cut, as it is termed, but the heavy work entailed is
carried out largely by putting one’s back into it rather than
by using the arms alone, for the arm muscles, particularly
in t,he case of the casual worker, quickly tire, whereas the
powerful muscles of the back are better adapted for prolonged heavy work.
The file is held as shown in Fig. 77 and the palm of the
left hand is used to apply the downward pressure required ;
the
feet
cbnavlrl
Y L”U,.L.
he
“V
ur~ll
.I”..
IT>QV+
L’y”‘c
ieft fotit, which is advanced
as illustrated in Fig. 78.
T,AJ~~+. the
T.AJ$T~~:E,~ t&y-
=r,
the
and the left knez slightly dent,
Fig. 77
68
Clearly, for heavy filing one must be well above
SO that the downward pressure can be maintained
:^ a:ls
--..
body movements giver. &ll $ay ; :A11 &L,.r:zc:e 1:
about arranging this, you will find it a great help
on a slightly raised platform.
the work
and the
_1!Lc
~_.I.
UIII:LL,I~~
to stand
Fig. 78
The chief difficulty the beginner finds when filing is to
file the work flat, for he tends to press the file handle
downwards at the beginning of the stroke and to press too
hard with the left ‘hand towards the end of the stroke.
This results in what is called fiddling, after the manner of
using a violin bow.
It is only with long practice that the art of filing with an
even flat stroke is acquired.
It is important that on the return stroke the downward
pressure should be relaxed in order to prevent damage to
the file teeth, but the file should, nevertheless, be kept in
light cnntact with the work surface so that the sense of
direction is not lost.
69
For light filing a.nd for finish filing the work, the body is
kept, more upright, the feet should be closer together, and
-......
._ d.“.‘lli.l’ll)
-AA:*:-,
t:-,c .“.v.ori<
is done &lrr:,Gsi.Gi-i.i-elx,,:
-JLL AL
, -’
w.?‘:::,
:::r- z:
1::s II 111
the work can with advantage be held higher. and not
below the level of the elbow.
The file is then best held with the tips of the fi.ngers of
the left hand, as this gives more delicate control.
When filing, the stroke should always be in the direction
of the long axis of the blade, as shown in Fig. 79, and not
across the axis of the file, as shown in Fig. 80, as this will
tend to roughen the surface of the work.
To maintain an even surface, it is he!pfA to chan.ge the
direction of filing from time to time, as shown in Fig. 79 ;
the fresh file marks then show up clearly and indicate
exactly where the metal is being removed.
Fig. 79
Fig.
80
The flatness of the surface should. be frequently checked
with a straight-edge or a rule, whilst its squareness can be
tested with a small try square.
The work should always be held so that it does not
project more than is necessary above the vice jaws, otherwise it will tend to vibrate, after the manner of a tuning
fork, and a screaming noise will be produced, accompanied
by a ridged finish on the work.
70
When metal is filed in the ordirrary way, a rough, burred
edge will be formed on the side away from the worker ;
rLf*
-.-” ‘,UC removed with a fine file to form a slightly
:c:s -L
x:uu:c:
chamfered edge.
Pinning. It may be found, particularly when using a. fine
file on steel, that the teeth become clogged or pinned, as it
is termed, and in consequence the surface of the work is
scored.
This can, to some extent, be prevented by chalking or
oiling the face of the file and reducing the downward
pressure applied.
The clogged teeth should be cleaned by means of a wire
brush, such as a strip of file card glued and screwed to a
wooden backing, as illustrated in Fig. 81.
WOOD H-ANDLE
Fig. 81
Where particles of metal, called pins, become firmly
wedged between the file teeth, they must be removed with
a pointed piece of mild steel
rod, otherwise deep scores will
be formed on the surface of
the work.
This method
Draw-filing.
of filing is used for filing flat
surfaces and also to remove
the marks formed
by the
-7-2
ordinary diagonal filing.
In
“u
this operation, the file, held
Fig. 82
71
evenly in the two hands, is worked to and fro along the
surface as depicted in Fig. 82.
Care shouid oe taken to keep the file ieve:- arid not in
allow it to rock or the surface of the work will become
rounded.
Draw-filing is particularly useful for accurately finishing
long narrow surfaces, for it is a scraping rather than a true
cutting action, but it is, however, difficult. to apply to
LEATHER
LIFTING
TAB
16?6*
Fig.
FILE
83
short work as-the length of the stroke is then too limited.
Hollow-curved
surfaces can also be finish-filed in this
way by using a half-round file, or in the case of very small
work a round file will be found more suitable.
Another method of draw-filing, largely used by instrument makers, is to place a large flat file on the bench and
to move the work to and fro along it whilst maintaining
firm but even downward pressure.
The file should be
brushed clear of filings at frequent intervals to prevent the
work being scored. A large file will be found most suitable
for draw-filing, as it allows the whole surface of the work to
be kept in contact with the blade. For the sake of convenience, the tang should be nicked on the grinding wheel
and then broken off ; the file is securely mounted on a
wooden base, as shown in Fig. 83, and a leather tag is fitted
to enable the file to be easily raised and turned over when
the reverse side is needed.
One side of the file should be marked with yellow paint
72
to indicate that it is to be used only for brass, whilst the
other side is reserved for filing steel.
Filing Aluminium
and its Alloys. Now that the model
engineer is making ever-increasing use of aluminium al,.. is,
particularly for small engine parts, some hints on filing this
material may be found useful.
Owing to its rather soft nature, aluminium tends to clog
and pin the teeth of an ordinary file.
To overcome this difficulty, special files known as milling
files hat-e been introduced, and of these the best known is,
perhaps, the Dreadnought file illustrated in Fig. 84.
Fig.
84
As will be seen, the cutting surfaces of this file are quite
different from the teeth of an ordinary file, for, here, a
series of curved cutting edges are widely spaced so that the
intervals between them allow the filings to escape and not
become wedged between the teeth.
This method of construction not only effectively prevents
pinning, but also promotes free and rapid cutting.
However, to obtain a good finish on aluminium parts, an
ordinary file should be used, and to lessen the tendency to
pinning only light downward pressure should be employed
when filing ; in addition, turpentine may be found helpful
when applied to the teeth of the file.
Scraping. When components such as lathe beds and slides
are machined by milling or pianing, their surfaces are left
slightly irregular, and also the $arts may be somewhat
distorted when clamped in place during machining.
To correct these errors a process of hand scraping is
employed, by which small amounts of metal are removed
from any high places, and in ,this way very accurate flat
surfaces are formed suitable for use in the highest class
machines.
13
This work is carried out with a scraper of the pattern
illustrated in Chaoter Two, or a tool made from a discarded
file, as illustrated ;n Fig. 85, may be used.
The first step is to make the surface as nearly flat as
possible by filing or machining, as it is important that the
work, should not rock on the surface plate if a clear picture
of the high spots is to be obtained.
The work is then lightly rubbed on a surlace plate, or
sheet of plate glass, which has been smeared with a thin
coat of marking compound ; the high spots are then shown
up clearly by the marking compound transferred to them.
The blue marking compound, which can usually be
obtained from a tool merchant, is best applied to the surface
plate in a thin, even coat by means of a piece of washleather glued to a flat wooden strip.
To remove these high spots, the work should be secured
in the vice and the scraper, held firmly in the two hands, is
used to pare away the metal, at the blued areas only, with a
well-controlled but decisive thrusting motion.
The correct angle at which the scraper should be held,
so that it cuts freely and without digging into the surface
of the work, will soon be found with a little practice.
In the first stage of the operation the scraper should be
worked in one direction only, and, after re-applying the
work to the surface plate and taking a second set of rubbings, the scraper is worked across the previous line so that
the two series of scraper marks are formed roughly at right
angles to each other.
This process of taking transfer marks, and then scraping
14
them down, is continued until the blue marking is found tcJ
when the work
he evenly d&t!-i!zed
o\‘er the surfxe
is applied to the surface plate.
Although at, first this may take a considerable
time,
\vith practice it \vill be found easier to estimate exactiy
where and how much metal should be removed to make the
surface Rat u;ithout undue waste of effort.
Ll’hen the scr:tper is used on hard cast iron it may be
found that it is soon blunted, and on no account should the
work !IC c!!ntir:ued if increased pressure has to ‘be musedto
make the too! cut, fbr this bvill only result in forming an
irregular and unsightly surface on the work.
To sharpen the scraper, it should be worked to and fro
along the oilstone after the manner of sharpening a woodworking chisrl and as illustrated in Fig. 86. When both
sides of the blade have been stoned, the end of the blade is
applied in a vertical position to the stone, as shown in the
drawing, and the scraper, while firmly held, is moved to
and fro al6ng the stone with a slight rcl%cking motion to
conform with the curvature at the end of the blade.
In time, as the tip of the blade becomes worn down with
stoning, it may be found necessary to have it reground to
restore the original form of the cutting edges.
Sawing Metal. The various forms of metal-cutting
saws
and saw blades commonly used in the workshop have been
described in Chapter Two.
Before starting the actual sawing operation ye*.1 must
make sure that the saw blade is suitable for the work in
Fig.
86
‘15
WRONG
RIGHT
TEETHb& IN.
FOR
PLENTY
OF
MILD
STEEL
NO
CHiP
CHIP
PITCH
CLEARANCE
CLEARANCE
TOO
FINE
18
1EETH
FOR
PER
IN.
TOOL STEEL
NO CHIP CLEARANCE
PITCH TOO FlNE
PLENTY
OF CH!P
CLEARANCE
TEETH
.-
41
,.
LCAJl
TEETb’
I,
,.ON
..,.,^
?k
1NC
FOR ANGLE
IRON.
COPPER
BRASS.
ETC
Ill”
SECTION
\’
32
TEETH
PER
(NC”
FOR THIN TUBING
SHEET
METAL
a
PITCH
TEETH
AT LEASl~ TWO
TEETH ON SECTiON
Fig.
TOO COARSE
STRADDLE
WORK
87
hand, and reference to Fig. 87 will show that there are two
main essentials : first, the pitch of the teeth, whether it be
14, 18, 24 or 32 teeth per inch, must be sufficiently coarse
to allow the chips to escape and not clog the saw ; the
broader the work surface the coarser the pitch shou.ld be.
The second and more important point is that the pitch of
the teeth must be such that the tips of at least two teeth are
always in contact with the work.
If this is not the case, all the cutting pressure may fall on
a single tooth, as represented in the drawing, with the
result that this tooth will probably be broken off and the
blade ruined. The narrower the work surface, the finer,
therefore, should be the pitch of the teeth.
The next step is tomark-out the
work to enable the sawing to be accurately carried out,
that is to say the cut must not en.croach on the finished size
of the work nor should an excess of metal be left behind,
Mding-out
the Work.
SAW BETWEEN THESE
TWO LINES
DIMENSION
LINE
Fig.
88
for this lrill later have to be removed by what may amount
to a laborious filing operation.
To denote the exact position and direction of the cut,
therefore, two lines should be scribed on the upper and
front faces of the work, as shown in Fig. 88.
The distance apart of these two lines should be a little
greater than the breadth of the saw cut, which should be
kept close to the outer line but just clear of the inner
dimension line indicating the size of the finished part.
Some mechanics prefer to saw along a single witness or
guide line, but in this case the line is obliterated as the work
proceeds and it may, at times, be necessary to disengage the
saw to see the direction the cut is taking.
Using the Hacksaw. As shown in Fig. 89, the saw should
be started against the edge farthest from the operator,
77
otherwise contact with the vertical face of the work at its
near edge will probably break off the saw’s teeth.
Deliberate, even strokes should be made at the rate of
some 60 a minute and; at the same time, the saw must be
well controlled so that the blade travels in a straight line
and does not jam in the cut, as this often leads to breakage
of the blade.
aly~drt
d saw cut
on the side of the work
furthest --from you
WORK
Fig.
8g
To prevent uneven wear of the teeth, use the whole
length of the blade and not merely its middle portion.
When sawing heady section material, tip the .saw from
time to time so as to iessen-the work surface in contact with
the teeth ; this will enable the saw to cut more freely.
Pressure must be relieved on the return stroke to avoid
blunting the teeth, but the saw must not be actually lifted
in the cut.
Should a blade be broken while cutting, the new blade
should be started in a fresh place, as the previous cut will
be narrower than that made by a new blade. This is due
to the fact that the teeth are set, as it is termed, that is to
say alternate teeth are bent outwards, as shown in Fig. go,
but with use this set is worn away so that an unworn blade
will tend to jam in the cut and will have its set worn away
unduly quickly.
The hacksaw, owing to the width of its
blade, is not well adapted for cutting on a curved path,
and for this purpose either an Abrafile or a fretsaw is
generally used.
Sawing Curves.
Fig. go
The Abrafile, described in Chapter Two, has a slender
blade of circular section and will readily follow a curved
line m,arked-out on the work.
If the figure to be cut is enclosed on all sides, a preliminary hole is drilled through which the blade is threaded
and then again secured in the saw frame.
Fig. CJI
7%
The work is gripped in the vice so that the cut is made in
a downward direction
and with the saw blade held
horizontally.
For larger work the fretsaw, with its deep throat, will
be found more suitable.
In this case, the work should be secured with G clamps
to a wooden table held in the vice by means of a projecting
tenon.
Fig.
g2
The blade is mounted in the frame so that it cuts on the
downward stroke, as illustrated in Fig. 91.
Cutting Metal. Apart from the various types ofsaws which
have been described, the cutting of metal, as far as bench
work is concerned, is carried out with shears and cold
chisels, all of which have been illustrated, together with a
short description, in Chapter Two.
Shears are used in exactly the same way as scissors, and
the cut is usually made with reference to a guide line, as
shown in Fig. 92, where the work is viewed during the
80
operation from the side, but when the shears used are of the
pattern shown in Fig. 93: that is to say with the upper blade
placed to the left side, cutting is more easily controlled if
the work is viewed directly from above.
When cutting deeply into sheet metal, it may be found
that with some shears the cut edges of the work tend to get
SCRIBED
/LINE
Fig. 93
in the way of the hand, but when the blades are of the
cranked form illustrated in Fig. 94, this difficulty is largely
overcome.
For cutting out curved work in flat sheet metal, either
the shears with curved blades illustrated in Chapter Two
are used: or a special type of shears with narrow blades,
known a!;, alligator shears, can be employed.
The curved-blade shears can also be used for such work
as trimming the edges of a sheet-metal cylinder.
81
The chief difficulty in shearing
heavy-gauge
sheet
material is to obtain sufficient cutting pressure, but this
can, to some extent, be overcome by gripping one leg of
Fig. 94
the shears in the vice, as shown-in Fig. 95 ; this allows the
5111 weight to be applied to the other leg and: in addition,
better control of the work is then obtained.
Fig- 95
a2
The ordinary tinman’s shears are made with one long
leg to afford greater leverage, but if an extension, such as a
length of tubing, is fitted to the workshop shears in order to
obtain increased leverage, care must be taken not to strain
the joint and so upset the contact between the cutting edges
of the blades.
When cutting sheet metal: the points of the blades must
not be allowed to close fully, as this will make an unsightly
mark on the cut surfaces of the work.
Using Cold Chisels. In the small workshop the cold chisel
is used mainly for cutting sheet metal and trimming
castings.
Although the various forms of cold chisels in common
use have been described and illustrated in Chapter Two, it
should be pointed out that for cutting sheet metal, supported on a block, the edge of the chisel should be curved,
as shown in Fig. g6A ; further, the cutting edge should be
formed to the correct angle of some 60 deg., as shown in the
drawing, for if the cutting angle is too acute the edge will
be easily broken, and if too obtuse the chisel will not cut
freely.
INCORRECT
CORRECT
@@(<!
0
edge
curved
correct
dngle too
obtuse
angle
Fig.
dngle too
dClJtC
g6
Cold chisels are supplied by the makers with the edges
correctly ground, and when blunted they can be resharpened on a Carborundum bench stone, but when the
chisel becomes badly worn, regrinding will be necessary.
I
83
After much use, the top of the chisel will become
over as shown in Fig. 97: and the sharp fringes so
are apt to cut the hand, or metal particles detached
hammer blows may endanger the eyes ; this end
burred
formed
by the
of the
chisel should, therefore: be kept smooth either by grinding
or filing away these rough edges.
For cutting sheet rnetal two methods are in common use.
In the first, as illustrated in Fig. 98, the work is supported
on a heavy iron block, and: with the chisel inclined away
from the operator, the cut is made toward? the body.
A succession of cuts is made in this way until the chisel
Fig. g8
84
breaks through ail along the scribed line and the work is
parted off.
It should be pointed out that considerable distortion of
the metal is caused both by the hammer blows and by the
wedging action of the chisel point ; in addition, this distortion will be increased if an attempt is made to cut
through thick sheet metal at a single passage of the tool, or
if the work is not well supported. on a rigid cutting block.
For this reason, when it is important to maintain the
flatness 0; the material, it is better to use the hacksaw for
cutting thick sheet metal.
In the second method, the work is held in the vice, as
shown in Fig. gg: and the vice jaws are then used to guide
the cutting edge of the chisel. The chisel should be held
at an angle to the work, so that it advances along the line
of the cut when struck with the hammer.
Although the material held between the \+ce jaws will
remain straight, the upper strip, particularly iE it is narrow,
till be distorted by the chisel and will tend to curl up into
a spiral, which when straightened out will have curved
sides and so wiil be of little use where a straight-sided strip
of metal is required.
When surfaces, Such as those on a casting, have to be
rendered flat by means of a cold chisel, the work must be
first marked-out on its sides to indicate the exact level ofthe
surface throughout.
The chisel is then worked across the surface, using a part
only of the cutting edge to enable the chisel to be driven
by light hammer blows ; following this, a second series of
cuts is taken crossing the first diagonally.
Do not carry the chisel right to the far edge of the work
or the metal will break away, but work from the edges
towards the centre.
When the chisel is used on large surfaces, preliminary
cuts should be taken across the work in two directions with
a narrow cross-cut chisel, and this is followed by cutting
down to the grooves so formed with an ordinary flat chisel.
Drilling with the Hand Drill.
A drilling machine is constructed to drill holes truly vertical to the surface of its
work table, but when a hand drill is used this alignment
has to be maintained with one hand whilst the other turns
the drill.
Usually, the drill is aligned with the aid of the eye alone,
but some of the larger hand drills are fitted with a spirit
level to enable the drill to be held horizontally.
When small drills are used, the hand drill is best held in
the vertical position, as the weight of the tool itself may then
impart sufficient pressure for drilling, and, moreover, fine
drills are less liable to be broken when used in this way,
especially if they project for only a short distance from the
chuck.
As a check on the position in which the drill is held, a
small. square may from time to time be applied to the work
surface and held in contact with the drill.
It is important that the hand drill should be held steady,
otherwise a bell-mouthed hole will be formed and there is
an added risk of breaking the drill.
06
With larger dri!ls it is better to use the hand drill in the
horizontal position, for this allows greater pressure to be
exerted by pressing the body against the breast piece, and
at the same time it is easier to maintain
the proper
alignment.
It may be remembered that it was suggested that the
bench top should be set horizontally with a spirit level ; if
this is done, the spirit level attached to the drill can be used
to align the drill truly with the work held in the vice.
Where the hand drill is not fitted with a level, the writer
has, on occasion, used a small circular spirit level borrowed from an old camera and attached to the shank of
the hand drill by means of a metal clip.
The Drilling Operation.
The I:ocation of drill holes is
usually marked by the point of intersection of two crosslines, scribed when the work is being marked-out for
machining.
A punch mark should be made exactly at this point, and
from it the circumference of the hole is scribed with the
dividers, as was described in Chapter Three, and as is
shown in Fig. IOO.
Now, it will be clear that, if the drill is not held truly
vertical to the work surface, its point wil: wander in the
direction in which the drill points, but as SI :.n as the drill
has entered up to :Its full diameter this wandering will be
checked by the sides of the drill itself. If, therefore, a
MARK
;-.;.i..
SCRIBE
@@+
DRILL
PILOT
OPEN UP
OPEN
OUT TO
Fig.
IOI
‘- 1,
centre drill of the type shown 1&A
I’ ig. I o I is used to start thehole and is entered up to the full diameter of the shank,
or nearly so, the drill following will be much less liable to
wander, as its cutting edges will have much greater support.
Except in the case of small holes, the centre drill should
be followed by a pilot drill, as represented in Fig. 100, and
the hole formed is, in turn, opened out with a larger drill,
but one rather smaller than the size of the hole required.
It will then be clearly seen if the drilling is so far concentric with the marked-out hole, but if this is not the
case, the hole must be trued by filing, before the final drill
is used.
However, this proshould,
as
cedure
far
as possible,
be
avoided by trying to
ensure that the drilling
is accurately
carried
out from the start.
When drilling blind
holes it is very important to start the drill
correctly, for, in this
case, the farther the
drill has entered the
more difficult it will
be to correct any error
of centring ; but if it
is found that the drill
has started 0%centre,
then the shallow hole
must be corrected, by
68
means of a. small round-nosed cold chisel, to make it truly
centra.1 with the scribed circle denoting the true position.
Avoid drilling in to the side of another hole, as shown in
Fig. 102, fbr this will almost certainly break off the point
of the drill ; but when this has to be done, fit a metal
plug into the cross-hole to support the point of the drill
wasit breaks through.
When drilling a hole in an inclined surface, as shown in
Fig. 103, it may be possible to avoid the hole running down
t.he incline if a small centre drill is first used, but it is better
to form a flat surface for the drilk either by filing or by
cutting out a step with a small cold chisel.
Drilling Sheet Metal.
Two
difficu!tirs
commonly
arise
when drilling sheet metal. First
a burr tends to form on the
under-side
of the sheet, a.s
illustrated in Fig. 104, and
interferes with the assembly
of the WGrk. at a later stage.
This can usually be overcome
by supporting the work on a
piece of metal instead of wood.
Fis. 103
Secondly, the work is apt to
spin and the hands are not free to prevent it ; but if a
clamp of the pattern shown in Fig. 105 is used to secure the
work to the bench, the sheet will be firmly held, and,
moreover, this will at the same time stop the work from
riding up on the drill and thus causing a burr to be formed
on its under surface.
As will be seen in the drawing, this clamp has a V notch
for the pa.ssage of the drill, and the two limbs of the V hold
the work securely, close to the drill hole.
Polishing Work with the Hand Drill.
The ends of rods,
the heads of screws, and other small parts can be polished
when secured in the drill chuck by revolving them against a
piece of emery cloth. The cloth should be supported on a
piece of wood to allow the end of a rod, for example, to
89
RURR
SPU.I
UP EiY DRILL
Fii..
104
centre itself by indenting the surface of the abrasive material
Reaming. This is the process of truing holes and making
them to the exact diameter required by means of a reamer.
The hand reames, shown in Fig. I 06, is made of hardened
tioLE BEING-DRILLED
steel and has a number of flutes with accurately ground
cutting edges ; in this case the flutes are straight, b.ut more
commonly they are of spiral form. The nose of the reamer
Fig. 106
90
is slightly tapered for a short distance to allow it to enter
under-sized holes.
This tool is intended to be used for the removal of only
very small amounts of metal, that is to say to bring to the
full. diameter
holes which have been drilled a few
thousandths of an inch under the required size.
To use the reamer, the squared shank is gripped in a tap
wrench, or other form of holder, and the tapered tip is
inserted in the hole ; the tool is then turned in a clockwise,
or right-handed, direction until it has passed fully into the
iwle.
The reamer is withdrawn from the hole by still turning
it im the same direction so as not to blunt the fine cutting
ed:ges.
On no account should the reamer be forced into the hole
or otherwise roughly used, for this may result in blunting
or chipping the cutting edges.
When steel is reamed, a plentiful supply of lubricant is
essential. When reaming a long hole, the reamer should be
withdrawn from time to time, and after the chips have been
cleared from the flutes, it should again be lubricated before
the work is continued.
Screw Threading.
Screw threading consists in forming a
thread either on the external surface of a rod or shaft, that
is to say a male thread, or in the interior of a hole when it is
termed a female thread.
As ready-made screws are usually purchased, the tapping
of holes to receive them is more commonly required in the
small workshop than cutting external threads, and so will be
first considered.
Cutting Internal Screw Threads.
From the drawing of a
screw thread shown in Fig. 107 it will be seen that the
outside diameter of the thread is equal to the diameter of
the rod, and corresponds with the nominal size of both the
tap and the die used for cutting this particular thread.
Further, it will be apparent tha.t the diameter of the rod at
the bottom of the threads, or core diameter, is considerably
less than the overall size of the rod.
91
This core diameter will vary with the coarseness or pitch
(Jf the thread used ; so to find the right size of drill to
form the hole for the tap, a table must be consulted which
takes into account both the outside diameter of the rod and
the pitch of the screw thread.
The hole to receive the tap is driiled somewhat larger than
the actual core diameter, both to provide working clearance
for the tap and to allow for the spreading and upsetting of
the metal whicl: takes place during the tapping operation.
If the tapping sizes given in the tables are used, it may
be found that, except in the case of very fine threads,
Fig.
107
considerable difficulty is experienced in tapping the hole,
for the tap has to bc worked in -::;ery slowly and carefully
to avoid breaking it.
If, however, the hole is drilled mthcr larger than the size
gi,ven, the tap will cut much more freely and without
risk of breakage ; in addition, it will be found that the tap
can be more readily kept on a. straight course in the larger
hole.
It matters little if the crests of the threads of the tapped
hole fall short of the roots of the external thread, for the
tips of a screw thread have but little strength.
An easy meth’od of finding the right size of tapping drill
to use is to insert the tip of the taper tap into the holes in
the drill gauge ; and when a hole is found which admits
the tap as far as the bottom of the threads at its tip, this
hole denotes the size of the tapping drill.
If you have any doubt in this matter, drill some trial
holes of various sizes in a piece of s’csap metal and tap them,
yGU can then select a hole which allows the tap to cut freely
02
and at the same time shows that a full, or almost full, thread
ha,s been cut. ‘51’hen you have found satisfactory sizes of
tapping drills for the taps you commonly use, make a table
of these for future reference.
When the tapping size hole has been drilled, its mouth
should be opened out, for a depth equal to about one and
a half threads, with a driil at least equa.1 to the outside
dianieter of the tap.
The appearance of the work is then as shown in Fig. 108,
which also illustrates the result of tapping a hole without
drilling a preliminary counterbore.
Should an attempt be
made to enlarge the mouth of a tapped hole with a fullsized drill, the countcrbore formed will be found to be
off-centre, as shown in Fig. 108.
The next step is to tap the hole, using the taper tap at
the start. A tap wrench suitable for the size of the tap
should be used, for if too much leverage is obtained the tap
will be easily broken.
The tap must at all times be kept truly vertical to the
RIGHT
WRONG
hole counterbored
two threads deep
before tdpping
counterbore
is
concentric with
hole
counterbored~ after
tapping. counterbore is eccentric
Fig. 108
93
NUT USED TO
STEADY TAP WHEN
STARTING
Fig. IO<)
work surface, and this is facilitated by using a nut on the
tap to act as a guide and to maintain an even bearing,
as shown in Fig. IGg.
A check can also be kept on the alignment of the tap by
applying a smal.1 square to the surface of the work.
Thin material can usually be tapped to the full thread
diameter by the passage of the taper tap alone, but in the
case of thick metal parts, or when tapping deep holes, the
taper tap is worked in slowly by advancing it half a turn at
a time and then turning it back for a turn to clear the chips.
After the taper tap has been entered for some distance,
it should be withdrawn and the second or plug tap is
worked down until resistance is felt ; this process is then
continued until the hole has been tapped for the required
depth.
Always keep the flutes of the tap clear of chips and use
plenty of oil when tapping steel ; cast-iron and brass do
not require lubrication.
Furthermore,
when a blind hnlc
is being tapped the chips must be cleared from the hole,
otherwise it may be thought that the full depth has been
reached when the point of the tap bottoms on a pad of
cuttings.
94
Should a tap be broken off in the work, it can be removed
with a pair of pliers if a hold can be obtained ; but if the
tap has broken off short, it may be possible to unscrew the
broken portion by carefully driving it round with a small
pin punch.
In the case of’large taps, a pair of fine-pointed pliers,
or a tool specially made for the purpose, may be used to grip
Jf these
the flutes and unscrew the broken fragment.
methods fail, the tap must be heated until it is softened and
then drilled out.
A
DIE
HOLDER
Fig. 110
Cutting External Thr
.~-. For all the work undertaken in
the small workshop tjr3 circular split die of the pattern
shown in Fig. : 10 is generalky used. Formeriy: these dies
were made witI: an adjusting screw, by means of which the
die could be set and correction made for wear.
The die is held in the holder as shown in the drawing ;
the central screw, A, is engaged with the slot in the die
and the screws at either side, B and C, are then tightened
to secure the die in place and lock it against the central
screw.
The size to which the die cuts can be adjusted over a
small range either by expanding it by means of the screw
A, or by contracting it with the screws B and C.
The chief difficulty in cutting a thread with this type of
95
die and holder is to form t!~ thread exactly in line with the
axis of the work.
The end of the rod to be threaded should be well tapered
with a fine file to give the die a lead and to enable it to grip
the work without excessive downward pressure having to
be used.
Care must be taken to hold the dieholder truly square
with the work when starting the thread ; this can, if
desired, be checked by means of a small square.
These dies are desig:ned to cut the thread to the finished
size at a singie passage over the work ; the chip holes
should be kept clear of cuttings, and when steel is being
threaded plenty of oil should be applied to the work surface
and the cutting edges of the die.
Formerly,
dieholders could be obtained fitted with
detachable guide collets which ensured that the thread was
cut squarely, and also, when required, a collet of the correct
size could be fitted to engage the stepped part of a shaft
when threading a portion of smaller diameter at its end.
In Part II of this book full instructions will be given for
making dieholders and collets of this type.
Soldering.
Soldering consists in joining together metal
parts by means of a solder, that is to say an alloy of lower
melting point which in part combines with the metallic
surfaces.
In addition to the solder, a flux must be used to prevent
the formation of metallic oxides which would interfere
with the process.
The best known flux is, perhaps, what is known as killed
spirits, that is hydrochloric acid, or spirits ofsalts, to which
metallic zinc has been added until all chemical action
ceases ; there are also various proprietary liquid fluxes of
this type such as the well-known Baker’s Fluid.
These
liquid fluxes are best applied to the work by means of a
tool formed from a piece of copper wire with a flattened
end as illustrated in Fig. I I I.
The other class of fluxes usually have a resinous or fatty
base, and these generally have the merit that, unlike
96
the former, they do not cause corrosion when used for
soldering fi.ne wires and other parts used in instrument work.
As the makers of some electrically-heated
soldering irons
advise that their products should not be used with an acid
Fig. I I I
Cux, care must be taken in such a case to select a flux which
does not damage the connections of the heating coils within
the iron.
As to the actual solder, the variety known as blowpipe
solder wiil be found most generally useful for all ordinary
work ; this has a high percentage of tin, which causes it to
run well and prevents it from tarnishing.
The compounds consisting of a combined solder and flux
mixture are now largely employed for special work, as they
Fig. 112
solder
Fig. 113
are easy to use and some at least are free from corrosive
action.
These can be obtained in the form of either a liquid paint
or a paste. In addition to these, solder is available as a
~
9:
wire with one or more cores composed of a non-corrosive
Euxing material.
When an iron is used for the saldering operation, its tip
must first be tinned, as it is termed, that is to say covered
solder
solder
Fig. 1x5
with a coating of solder. After heating the iron to a temperature sufficient~ to melt the solder, it is dipped in the
flux and then applied to the stick of solder ; the solder
should run over and adhere to the surface of the iron, but
if it does not readily do so, thi tip of the iron should be
cleaned with an old file to remove the 5lm of oxide and a
further trial made.
In this way all four faces of the tip should be tinned as
shown in Fig. I 12 and the iron is then ready fcr use.
Should the iron be subsequently overheated, the tinning
will be burnt off and retinning will be necessary.
After the work to be soldered has been thoroughly
notch
Fig. 116
cleaned and rendered
corrosion, it is painted
the solder adhering to
slowly moved along its
quite free from grease or surface
with liquid flux and the iron, with
its tip, is applied to the work and
surface, as represented in Fig. I 13.
98
The same procedure is adopted when, for rsamplr,
sol,dering a blishing into a tank.
This shoul,:l, result in the application cjf a thin, even la)-er.
or fillet of solder, as illustrated in Figs. I 14 and I 15, but
some practicr: Gil be required before this can be done neatly.
For soldering wires or Bolvden cal~les, an iron lvith a
notch fLrmec1 at it3 tip, as shown in Fig. I 16, will br found
most convenient, as the solder lvill lie in the nr~ch and is
t.hcn readily applied to the work.
Some combined solder-flux compounds can be used iI,\a
similar manner with the soldering iron, but of thcsc* sc,r.nr
arc I)ettrr adapted for this purpose than othr~s.
A process which is much more easily carried out than
soldering with an iron is known as sweating. ‘I’his consists
either in coating the parts with a layer of solder, or mercl~.
in appl+ng to the surfaces concerned a solder-flus paint3
!,I:’ ~astr, i,Ind then heating the parts while 1tic*!. at’(x ~)r~:‘sscd
together, until the solder mcllts.
Sweating carried out in this way forms a neat joint, as
no superfluous solder is used, and, moreover, hardly an)’
skill is needed t,o obtain a good result.
The mild steel used gcncdiy
Hardening and Tempering.
in the workshop for constructional work cannot be hardened
in the ordinary way, but tool or carbon steel from \vtlich the
workshop toois are made can be readily hardened.
The essential difference between the two types of steel
is that mild steel has a low carbon content, xvhereas tool
steel has much more carbon combined with it.
Silver steel is a form of tool steel which can be easil),
hardened, and it is, therefore, most useful for making small
tools and othex components MThich need to be hardened.
To harden, tool steel, it is heated to a bright cherry red
colour and then quickly dipped in water. This leaves the
steel dead hard but rather brittle, so that where toughness
is required, as in the case of cutting tools, the work must be
tempere& after being hardened, before it can be used
effectively.
To temper the steel, it must first be cleaned with a piece
99
of emery cloth until it shows a bright surface ; it is then
carefully heated at a place weii away from the cutting edge
and the flow of colour formed is closely watched. The first
colour noticed will be a pale yellow, and, as the work is
heated further, this will be succeeded by a play of colours
ranging from a dark straw to a deep blue.
For oldiiiary metal-cutting tools a straw colour will give
about the right. de,gree of hardness, and blued steel will
yeneraily be found milch too soft.
When the straw tint has spread to the cutting edge from
the heated portion of the work, the tool is again quickly
dipped in water.
Nowadays, metal-cutting tools are largely made of highspeed steel, which contains tungsten or other scarce metals ;
tins steel is hardened and tempered by a special process of
heat treatment, and no attempt should be made to soften
or harden tools made of this material. Short lengths of this
steel, suitable for making tools, are supplied by the manufacturers properly hardened and ready for grinding to the
shape required.
Although, as has been said, mild steel cannot be hardened
as can tool steel, it can, however, have its outer surface
hardened, whilst the centre portion remains soft, by a process known as case-hardening.
T,his consists of heating the steel, while in contact with a
case-hardening
compound, so that extra carbon becomes
combined with the surface layers of the steel and, in effect,
converts this portion into tool steel.
This out.er layer of toolsteel can then be hardened in the
manner already described, but for most purposes subsequent
tempering is urinccessar) as the inner portion of the steel
remains soft and retains its full strength.
CHAPTER FIVE
A Simple Dep$h Gauge-A
Rule Stand.
I
Now that we have considered most of the ordinary workshop
(?nerations carried out with hand tools it is time to put this
to useful account in making some small articles of equipment
that may be helpful in the workshop.
A Simple Depth Gauge. The illustras TO
tion in Fig. I I 7 gives a general view of
the gauge and shows the main points of
its construction and design.
You should notice two things : one, thab the drawing is
three-dimensional,
that is to say it represents the device in
three planes in space and shows its length, breadth, and
thickness in one v4ew. The alternative to this is to make three
separate drawings, showing the plan view, as seen fs~om
above, and, in addition, an end and side elevation to represent the end and side views respec&e!y.
hlorecver,
from
the single drawing you will be able to see at a glance exactly
what the gauge is like, just as though it were actually before
you ; you are, therefore, saved the trouble of trying to build
up in the mind’s eye a picture of the object from three
different drawings.
A drawing of this type is termed Gometric, and you will
see that, unlike an artistic drawing, all side and end lines
are parallel and dc not converge to represent a perspective
view.
Secondly, you will see that all the parts are numbered, and
these same numbers are used in all subsequent drawings
whenever the parts are shown. When you do any machine
drawing or sketching for yourself, try to adopt this
methodical way of working in order to save confusion and
loss of time when making components from drawings.
100
101
The gauge is used in the same way as the depth gauge
described in Chapter Three, that is to say, the base block is
held against the work while the spindle is pushed to the
bottom of the hole to be measured, and the clamp screw is
then tightened.
Although the spindle is not graduated, as in the former
case, it has the advantage that it can be used in very small
holes.
To record the actual depth,
the length of the spindle projecting
below
the
base is
measured with a rule.
The base block, part No. I,
is best made of steel, both
to resist wear and to look more
it is formed
workmanlike ;
by cutting off a piece I in.
in iength from a bar + in. wide
and # in. thick, or it can be
sawn out with a hacksaw from
a larger piece of material.
When the base has been cut
to shape, the edges are filed
straight and square and the
surfaces are finished with a fine
file to give a good appearance ;
all edges are then chamfered
with the file to remove their
Fig. I 17
sharpness.
The upper and lower surfaces are best made flat by
rubbing the work on the bench file as previously described.
The under surface, where it will come in contact with
the work being measured, must be made quite Aat by
using the scraper in conjunction with the surface plate.
The next step is to paint the upper surface and one side
with marking fluid to enable the drill hole centres to be
marked-out.
For this purpose, the jenny callipers are set to a in. and,
102
as shown in Fig. I 18, a line is scribed along the upper
surface, and then on the front face with the callipers seset
to & in.
With the cailipeirs set to -$ in., the cross centre lines are
then scribed on these two faces, as shown in the drawing.
The points of intersection of these centre lines are marked
with a centre punch, and the upper hole is drilled & in.
right through to take the spindle, but if you happen to hase
a Q-in. reamer. drill this hole with a No. 31 drill and ream
it to the finished size. The two ends cf the hole should be
, xROUNOEO
Fig. I 18
very lightly countersunk with a centre drill to remove the.
sharp edges.
The hole at the side of the block is drilled with a No. 42
drill through into the previous hole ; it is then tapped to
receive the 6-B.A. clamp screw.
After th.e drilling and tapping have been completed, any
burrs which may have been formed are removed with the
scraper, and the base block is then finished and ready to
receive the spindle.
The spindle should be made from a length of &in.
diameter silver steel, as this material is usually straight and
accurate as to size. Three inches will probably be sufficient
103
for the length of the spindie, but, if desired, it can be made
to the full standard length of G in.
When the spindle has been cut to length, the ends are
filed flat with the aid of a square, and the upper end only
is rounded OK and then polished by using the hand drill as
previously described.
The clamp screw can quite well be made from a knurled
terminal screlv, preferably of brass, as this wil! not damage
the spindle.:
The diameter of the head of’the screw must not be greater
than g in. or the base block will not lie flat on the work
when measurements are being made.
The threaded portion of the screw; should, if necessary,
be cu.t short so that the screw itself does not project unduly
and spoil the neat apprarance of the finished. gauge.
A &clle Stand. This easi!)--made form of rule holder is
used, as previously described, to hold the rule in the upright
position on the surface plate when setting the scriber point
of the surface gauge. The stand described \\-a~made to
take rules up to & in. thick and 8 in. widc. but it will also
accommodate rules of other sizes.
The general, isometric, vie\\-is shown in Fig. I 19, and
the component. parts are i.llustrated in Fig. 120.
The base block is made from a ~&in. length of $-in.
square steel bar, and, as will be seen, all the drilling work is
confined to the front face.
The steel block, part No. I, should be carerully filed
square and to a good finish ; the edges are then chamfered
with a fine file to remove the sharp corners.
As it is essential that the holder should stand evenly on
the surface plate and without rock, its under surfa:,e must
be scraped true so as to form a good seating surface.
When this work has been completed, the front face is
painted with marking fluid and then marked-out as shown
in Fig. 12:).
The hole to receive the 6-B..4. screw*;,used to fix the spring
clip, is marked-out with the jenny callipers 3 in. from the
!e‘ft-hand end of the block and on the ceRtre line of the
104
front face, that is to say 8 in. from either the upper or the
lower edge.
The holes for the register pins are marked-out
& in.
from the ri,+t-hand
edge and & in. from the upper and
lower surfa; es respectively. All these centre points are then
marked wj.h a centre punch, and the screw hole is drilled
with a No. 4.2 drill to a depth of; in. and afterwards tapped
SCREW
6 RA
Fig. 119
for a depth of some & in. The register pin holes are drilled
with a No. 53 drill to a depth of $ in.
To complete the work on the base block the register pins,
No. 5, have to be fitted. These are made from & in.
diameter silver steel, but as the diameter of the drilled holes
is some three thousandths of an inch less than the diameter
of the rod, the silver steel will have to be slightly tapered
at its end before it can be fitted. An alternative method is
to use a piece of r6-gauge bicycle spoke and drill the holes
with a &-in. drill ; as in this case the difference between
the diameters is only one and a half thousandths, the spoke
can be pressed into the holes once it has been started by
slightly tapering its end.
105
‘I’apering the rod is best done by supporting its end in a
notch filed in a piece of brass secured in the vice, and &en
turning the rod with the fingers while it is filed with a fine
file. In any case, before fitting the pegs tr, the block, it is a
good plan to make a preliminary trial on a piece of scrap
metal to find out how much taper is needed to allow the
pins to be pressed into place.
DRILL NO 42 /
TAP 6 IBA
DRILL
No53
I
6BA
WASHER
Fig. I20
6BA
SCREW
!U6
After two pins have been suitabl!, tapered and cut oh
to $ in. in length, their heads are rounded off and polished
as previously described. Press the two pins into the block,
using finger pressure only, and check their vertical alignment \\-iththe square either resting on the surface plate, OI
applied 10 t!le under surface of the block.
If your drilling has been accurately carried out, the t~vo
pins should stnnd vertically one albove the other, but if this
is follntl not to bc the case, a,ny error must be corrected by
filiilg ;t flat on one pin.
\Vhen ail is in order, the pins should be pressed home in
the vice, leaving 11’32 in. of their ends projecting.
‘l’he next step is to fit the leaf spring, Xo. 6, that holds the
rrllr in position. This is made of z&gauge spring brass,
‘1s this material xvi11 not. scratch the ruic as wrou!d steel
i,lc~.i;. spt.ing ; ;tridz rric,rrover, it is rrruch more easily tlr illccl
‘!d cut to shape.
“I‘he brxs is paint,ed with marking fluid, and after it has
been marked-out with the jenny callipers, a strip 4~in. wide
is cut off.
In order to afford a better hold of the material while it is
being drilled, it is not cut to length until after the LVo. 34
drill hole shown in the drawing has ‘been marked-out and
driilcd,
The end portion of the strip is then polished with a piece
of fine emery cloth, and t.he free end is made slightly curved
with a fine file. \Then the strip has been cut off to a length
of I 1~in., it is given a double curve, as shown in the dralving,
by bending it with the aid of the round-nose pliers, or it
can be formed equally well by bending against a piece of
rod held in the vice.
A distance pi,ece, No. L?, is fitted behind the spring to
allow the latter to beat evenly on the rule when in position.
‘This compr;ncnt is cut out from a piece of brass & in. thick,
and after it has been marked-out in accordance Gth the
drawing, it is drilled with ~1No. 34 drill to !%n a clearance
hole for the screw.
To complete the list of components,
;L 6-B.A. brass,
chamfered washes and a 6-B.A. round-headed, brass screw,
8 in. in length, are reo.uired, that is to say parts ;s and 4.
The rule holder can now be assembled ; and it should
be noted that the register pins serve the double purpose of
aligning the rule and at the same time holding the spring in
position, for the spring should fit closely between the
projecting ends of the pins.
The rule should now be sprung into place, and if it is
found that the hold is too firm, or too light, the spring
should be removed and reset accordingly by means of the
round-nose pliers.
101
chamfered washes and a G-B.A. round-headed, brass screw,
8 in. in length, are required, that is to say parts ~3and 4.
The rule holder can now be assembled ; and it should
be noted that the rrgistcr pins serve the double purpose of
aligning the rule and at the same time holding the spring in
position, for the spring should fit closely between the
projecting ends of the pins.
The rule should now be sprung into place, and if it is
found that the ho!d is too firm, or too light, the spring
should be removed and reset accordingly by means of the
round-nose pliers.
INTRODUCTIONPART II
WE have now finished considering workshop premises, the
furniture needed in them as well as the hand tools desirable
if a full range of activity is to be pursued.
The time has now come to review the machine tools
required if the beginner is to extend both his facilities and
his skill.
CHAPTER ONE
Lever-feed and Rack-feed Types Electric
Drilling
Machine-Driving
the MachineDrilling
Speeds-Machine
Vice-Table
V
Blocks-Work
Clamp-Drill
Chuck-Table
Stop-Depth-drilling
Stop and GaugeDrilling Operations-Drilling
into a Crosshole-Drilling
on an Inclined
SurfaceCross-drilling
Shafts-Drilling
for Tapping
-Tapping
in
the
Driliing
MachineCountersinks-Counterbores
and Pin Drills.
‘THE drilling machine,
as opposed to the hand drill, has
the great advantage that it can be relied on to bore holes
truiy at right-angles to the surface of the work ,and with
great accuracy
as regards size and
position.
ING
This is ensured by mounting both
the headstock of the machine and the
work table in accurate alignment on a rigid column ;
further, the high sFeed obtainable
with a power drive
makes ,successful drilling possible with even the most
slender drills.
The smaller drilling machines are
Types of Machines.
usually of what is termed the sensitive type, that is to say
the lever mechanism that feeds the drill is so designed that
the pressure on the drill can be readily felt by the hand,
as disti,nrt from the feed pressure which is applied by a
screw mechanism as in the lathe tailstock or in the cruder
forms of drilling machine.
In the simplest form of machine the feed lever is connected directly to the drill spindle, which carries the
chuck holding the drill and is moved downwards when
pressure is applied to the hand-feed lever.
A well-designed machine of this type, illustrated in
109
Fig. I
Fig. I, is the “ Model ‘Engineer ” Drilling Machine which
takes drills up to $ in. .in diameter.
Although this machine cannot be purchased, as the
design hardly lends itself to economic commercial production in view of the number of small components required
and the accurate
hand-fitting
of the bearings rightly
recommended ; ne\rertheless, castings of good quality are
readily obtainable, and from them an accurate, high-class
machine can be built by those possessing the necessary
skill and equipment ; moreover, t.he machine has b,sen
111
so designed that a11 the machining can be carried out in a
I.athe of 3+ in. centre height.
The writer built one of the machines several years ago
and, a.s a result of careful hand-fitting, no wear has become
BELT STRIKING CONTROL
Fig.
2
112
apparent and the machine’s accuracy has been maintained in spite of prolonged use.
Reference to Fig. 2, depicting the general construction
of the headstock, will show that a ball bearing is fitted to
the spindle to take the thrust of the feed lever, which is
returned to its upper position by means of a spring ; a
counterweight can, however, be used for this purpose to
ensure a very delicate and highly sensitive feed motion.
The three-step drive pulley, in conjunction with the adjustable jockey pulleys, provides for a wide range of speeds and
correct tensioning of the driving belt.
The Rack Feed Machine.
When the larger sizes of
drills are used in machines fitted with a lever fee% acting
directly on the drilling spindle, it will be found that considerable hand pressure has to be applied to the feed handle
to make the drill cut ; those who have used a hand drill
\viI! be well aware of the heavy pressure needed in this
case. .4lthough the leverage, and with it the pressure on
the drili, can be increased by lengthening the feed lever,
it is not usual in small machines to provide a leverage
greater than about four to one if a lever of reasonable
length is to be used.
To overcome this difficulty and to provide adequate
drilling pressure together with a sensitive feed, a more
complica,ted mechanism consisting of a rack and pinion
feed is generally employed.
The headstock mechanism of a dril!ing machine of this
type is illustrated in Fig. 4, and it will be apparent that,
when the feed lever is depressed, the pinion attached to it
will rotate, thus causin,g the rack of the spindle sleeve, or
quill, to move downwards and feed the drill against the
work.
The leverage obtained in this way is usually some sixteen
to one ; a great advance on the limited leverage provided
in the more simple type of machine.
The sleeve on which the rack teeth are cut is known as
the quill, and machines so constructed are called quill
machines to distinguish them from the previous type.
-
the Champion drilling machine, illustrated in Fig. 5.
This machine, once popular for many years, took drills
up to i in. diameter. A ball thrust bearing was fitted at the
lower end of the spindle and at its upper end the three-step
driving pulley was mounted on a sleeve in or=der to reheve
the spindle from side pressure due to the pull of the driving
belt.
___~
______,~~_~~~~~.~.-~~~~,~~‘~~‘~~~~~
,--n
-rack
\
*quill
return.
cover
Fig. 4
-
i
i
i
I
113
t,The quill does not, of course, rotate but moves upwards
: and downwards in the headstock under the control of the
;feed lever. Further, it will be seen that the feed lever is
returned to its starting position by means of a coil spring
bontained in a housing enclosed by a cover plate.
‘:, The drawing in Fig. 4 represents the working parts of
115
A 4 in. diameter canting work table W:IS fitted and was
provided with a graduated angular scale and register pin
for setting the table to the exact horizontal position.
The great length of the sliding headstock casting where it
engaged the column made for rigidity and ample provision
was made for adjusting the belt tension by means of a
sliding bracket ca.rrying the jockey pulleys. An adjustable
stop as illustrated in Fig. 4 could he clamped to the spindle
to regulate the depth of drilling. It is to be hoped that
someone will be found to market the machine again, for it
is one eminently suited to the needs of the amateurs
workslop.
The particular “Champion” drill illustrated was modified
by the author in order to provide a readily obtainable range
116
Fig. 5
of spindle speeds in conjunction with a motor fitted with a
2-step pulley.
The Cowell drilling machine, illustrated in Fig. 6 is
designed for those who require a rather larger machine
of # in. drilling capacity and with a work table 5 in. in
diameter.
This machine is essentially of simila,r construction
to
the preceding model, but has certain detail modifications.
As before, the spindle runs in a quill operated by a rack
and pinion gear, and the mounting of the drive pulley on
a sleeve ensures that the spindle is not subjected to the
strain of the pull of the driving belt. A neat form of return
mechanism for the feed lever is enclosed in the housing
of the pinion gear.
The rotating work table is of the fixed type and not
tilting as in the previous machine;
this overcomes the
difficulty that is sometimes experienced
in resetting a
tilting table accurately after the machine has had much
use. The jockey pulleys slide on an inclined shaft so that
Fig. 7
118
the belt can be aligned correctly with any of the steps of
the driving pulley when the speed is changed.
The ball handles fitted to the feed lever and the table
setting clamps make for easy handling and add to the
appearance of the machine as a whole. As with the “Champion” drilling machine, the Cowell drill depicted has also
been modified by the author to provide a suitable range of
spinc!le speeds.
Selibcsntained
Electric
Drill.
The drilling machine
shown in Fig. 7 is the Black and Decker hand drill mounted
on a drilling st.and specially designed for the purpose.
The drill itself can be readily detached from its stand and
used as a portable drill in the workshop or garage ; moreover, it can be employed to mount a grinding wheel, a
polishing buff; or a wire brush for decarbonising.
Although this type of drilling machine has the advantages
enumerated above, it will be apparent that the limited
as compared
with a separately-driven
speed range,
machine, detracts from its utility as a general purpose
machine in thle small workshop, where slow or moderate
speeds are sometimes essential.
Driving
the Drilling
Machine.
Drilling machines are
usually driven by means of a belt, for this provides a drive
that is both quiet and flexible and, at the same time, the
drilling speed is readily varied to suit the occasion by
moving the belt from one step of the driving pulley to
another.
In small machines, such as those described, the drill
spindle is driven by a round belt which is maintained in
line with the driving pulley ‘by means of a pair of jockey
or guide pulleys.
The belt tension can be adjusted either by altering the
position of the jockey pulleys or by raising or lowering the
headstock on the column of the machine.
I,n some instances a countershaft
is incorporated
to
ena’ble the machine to be driven by a flat belt from the
workshop lineshaft. The “Model Engineer”
machine is
designed to carry a countershaft should this be required,
and in this case a belt-shifting gear is fitted to move the belt
on the fast and loose pulleys when starting and stopping the
machine.
Fig. 0
Small high-speed drilling machines can be driven by
means of a sewing machine belt, but it is important, when
using these round belts of small cross-section, that the
fastener should bp properly fitted tc prevent its tearing out.
The correct method of fitting a steel U fastener is shown
in Fig. 8 ; it will be observed that the cut ends of the belt
are butted closely together, and the lower part of the U
projects but little below the belt to ensure that the fastener
k kept we?1 clear of the bottom of the V in the pulleys.
When fitting fasteners r,f this type, the ends of the belt
should be drilled exactly centrally with a & in. drill,
a,nd at the correct distance from the joint to allow the
final closure of the fastener to bring the ends of the belt
firmly~.together.
1x
Fasteners fitted in this way should be noiseless in action.
and proof against tearing the belt provided that excessive
belt tension is not used. For those who wish to avoid
using belt fasteners, endless round belts are now obtainable
in lengths suitable for driving small machine tools.
Probably, the most convenient method of driving a
small drilling machine is to employ a direct belt drive from a
motor installed near the drill, as illustrated in Fig. 9.
Although only a single driving pulley is shown~ the speed
range of the machine will be correspondingly increased
if a t,wo- or three-step pulley is fitted to the motor shaft.
The simplest form of installation is depicted in E’ig. A,
and it will be seen that all that is :,equired is to fix the
motor to the bench and fit the belt.
Tn this case, the motor occupies v&able
space on the
bench ad is not protrctcd in any way. 3Iethod ii affords
some protection for the motor, is more compact and, in
the cast of a low bench, raises the machine to a more
convenient working position.
The arrangrmcnt
sho\\n in ltig. go is widely used, tbt
the bench top is then but little encumbered and the motor
is well1 protected from metal cuttings.
When the motor is
installed in this way below the bench, it can be attached
to a wooden base sliding in strips secured to the underside
of the bench t.op ; this allows the motor to be easil)
removed for periodic cleaning and oiling.
When much fine drilling has to be undertaken, the
raised position of the drill, as in Fig. gn, will he found a
*great con\,-nience in affording the operator a comfortable
working position without excessi\:e stooping being required
to bring the eyes close to the work. Before leaving the
subject of driving the drill, it must be emphasised that a
switch should be fitted close at hand to enable the machine
to he stopped instantly in an emergency.
When planning the drive of a drilling
Drilling
Speeds.
machine, account should be taken of the size of the drills
to be used, for although a heavy machine must be capable
of driving lar-ge drills at comparatively
slow speed, tt
--I
3
-J
Q
Fig. ‘J
sensitive type of machine used for light drilling with fine
dribs will need to be driven at high speed.
The following tab!.e gives the speeds recommended by
dril.i manufacturers for drilling mild-steel for commercial
purposes, but in the s-mall workshop, where the rate of
production is of less importance,
these speeds may be
reduced.
Drill diam.
in in.
Ii
4
-
High-speedSteel Drills/ Carbon Steel Drills
r.p.m.
r.p.m.
--.-_1
4,000
1,800
2,000
1,500
600
900
4
1,100
900
450
--_,------ -I
550
‘350
750
_L_~
32%
210
240
‘Fhesr speedsmay be doubled when drilling brass and aluminium.
Although the figures given above are by no means
absolute, they will serve as a guide when arranging the
details of the drilling machine drive from an electric motor.
It will be apparent that high-speed steel drills can be
driven at much higher speeds than carbon-steel drills,
and for this reason they are to be recommended for use
with high-speed self-con.tained electric drills ; moreover
the former retain <heir sharpness for a longer trme and are
much less easily broken.
When drills are driven too fast the cutting edges may
become quickly blunted, and overheating will arise which
will draw the temper and soften the drill point. The speed
should be reduced when drilling cast-iron otherwise the
cutting lips may become worn and the drill will then tend
to bind in the hole.
It is important where high drilling speeds are used that
the cutting edges of the drill should be maintained in a
really sharp condition in order to ensure free-cutting and
avoid rapid blunting of the driI1 point ; it may, therefore,
be advisable to restrict the speed until some experience has
been gained.
Drilling
Machine
Equipment-Drills.
These
have
been described in Part I where a list of the sizes manufactured will also be found.
Machine Vice.
For supporting the work en the machine
table when drilling, a machine vice will be found essential both to align the material correctly and to prevent it
from turning with the drill and damaging the fingers.
Fig. 10
A small, accurate machine vice, manufactured by Messrs.
Myford and well-suited for use in connection with the
small drilling machine, is illustrated in Fig. IO. It is
essential for accurate drilling that the work held in the
vice should lie parallel with the drilling machine table
and at right-angles to the drilling axis ; to ensure this
the work surface of the vice must be parallel with the underside,,of the sole plate, and the fixed jaw must stand at rightangles to this surface.
When these conditions are satisfied, any work secured
in the vice will automatically be truly aligned in the drilling
axis.
As wil! be seen in the drawing, a loose, swivel jaw-piece
is included fbr holding tapered or irregular work, and
Fig. I I
bolting slots are provided for securing the vice to the work
table.
Heavier vices of greater holding capacity and suitable
for use with larger drilling machines are also obtainable,
but it is advisable to check the accuracy of any vice, not
of reputable make, before putting it into use.
Table V Blocks.
A V block or a pair of V blocks: is
used for holding round shafts and other parts on the work
table of the driiling machine.
The Eclipse V blocks,
illustrated in Fig. 12, will be found especially serviceable
as they can be readily clamped to the work table as illustrated in Fig. 19. ‘I’he work itself is secured in place in
the block by means of the screw-clamp supplied with each
set of two blocks.
Another useful appliance for this type of work is the
Rlyford saddle or table V block, illustrated in Fig. 13.
T:ic sole plate can be drilled, as requned, for bolts to
secure the device to the work table and, if necessary,
clamping strips can lw fitted to the upper surface of the
blocks to hold the work in place.
Work Clamp. For Ii-curing work, such as sheet metal.
which cannot be held ir: the vice for drilling, a work clamp
of the pattern illustrated in Fig. I I will be found useful.
As will be seen, a V notch is formed in the clamping
limb to provide a space in which the drill cm operate.
The work should be supported on a piece of ebonite,
hardwood, or metal in order to protect the table from
possible damage and siso to prevent a burr being formr:d
on the under-side of the work.
It is always advisable to fit a bestDrill Chuck.
quality chuck to the drilling machine, for this will ensure
that the drill is always held truly and securely, provided
that the chuck is treated in a .reasonable manner.
During some drilling operations it is
Table
Stop.
necessary to swing the drill table to the side and, at the
same time, to maintain exa,ctly the height to which it is
set. This can be ensured if an adjustable stop collar, of
the form shown in Fig. 14, is fitted to the column of the
machine.
When the height of the ta,ble has been set, the
stop is brought into contact with the under surface of
the table bracket and then clamped in place.
Full directions for making this attachment are given in
Chapter Six.
BRASS
Fig.
14
PAD
Depth QriIling Stop and Gauge.
When it is required
tu drill a number of holes to an equal depth, it saves much
time and uncertainty if the drilling machine can be set
to drill to a definite limited depth.
In the case of a
machine such as the Champion, illustrated in Figs, 4 and 5,
this is readily en&red by using the adjustable clamp collar
fitted to the s+dle.
The collar is set by means oft a rule, as shown in Fig. 15,
Fig. 15
and, when the adjustment has been made, the collar is
secured in place on the spindle by tightening the clamping
screw ; the downward travel of the spindle is then limited
by the collar coming into contact with the face of the
driving pulley.
To measure the downward feed of the drill when using
a quill-type
of machine,
the quill itself is sometimes
graduated, or as an altern&ive method, a poeion of a rule
is fitted into the split quill-housing, as shown in Fig. 16.
Here, a small leaf spring is fitted behind the rule to provide
frictional contact, and thus enable the rule to bc se* to
the zero position a t an iinch mark at the start of the drilling
operation.
The sinpie lever-feed drilhng machine can also be fit&
with a depth stop and gauge, but the actual construction
must depend on the design of the individua! ma?:ine.
Drilling
Operations.
The general principles involved
in drilhng with a drilling machine are similar to the:,:
employed when using a hand
dri,il, as described in Part One
which of course should be
read before the present volume. In the former case the
machine has its own motive
power and ensures accuracy
of drilling ahgnment, leaving
c;nlv the feeding of the drill
and, perhaps, the steadying
of the work to the operator.
As before, the location of
the drill hole is accurately set
and
its
bY marking-out,
centre is then marked with
a centre punch.
Fig. IL
If a large drill is started in
the small punch mark so formed, it is quite possible that it
will wander from the true centre owing to lack of guidance.
To obviate this, the punch mark is enlarged with a small
centre drill of the form illustrated in Pig. I 7. When drilling
small holes it will be advisable to use the smallest standard
size of centre drill with a body of & in. diameter and a
drilling tip of 3$54 in. diameter,.
These fine drills should be run at high speed with plenty
of lubrication and the feed should not be forced or the
slender drill tip may be broken off.
The centre drill is fed. in until a countersunk hole is
formed equal to the diameter of the following drill. Should
the diameter of the hole to be drilled be app,reciably
greater than a in., it is advisable to drill ;1 preliminary
pilot hole both to save time and 1~ enable the larger driii
to cut more freely and with less feed pressure.
The next step is, therefore, to drill an $ in. pilot hole
in the work, and there need be no fear of this being out
of centre if the 3 in. ccntre drill has been previously entered
to its full diameter.
:,,
Finally, the hole is enlarged to its full diameter in one
or more stages, but it should be borne in mind that when
larger drills are used the drilling speed should be reduced
accordingly by altering the position of the belt on the step
,pul!eys.
Wherl drilling holes in sheet metal, it is advisable to
secure the work to the drilling table by means of a clamp
as illustrated in Fig. I I, and, in addition, the rate of
feed should be reduced when the drill is nearly breaking
through or it may grab and di.g into ihe work.
If the drill is carried right through the work, take care
that the drill point does not come into contact with tbe
table ; a work table honeycombed as a result of thoughtDamage of
less drilling is the sign of a careless workman.
this s,ort can be avoided, either by allowing the drill to
pass through one of the table slots, or by supporting the
work on a piece of metal, ebonite, or hardwood.
Before
drilling a second hole, remove any burrs formed by the
previous drilling as these will prevent the work from lying
flat on the drill table.
When fine drills are used, there is a tendency for the
drill to become jammed in a deeply drilled hole ; this
PLUG
Fig. 18
can be avoided by withdrawing the *drill at frequent intervais and freeing it from cuttings, with an oily brush while
the machine is still running.
Drilling
into a Hole.
Where a hole has to be drilled
to meet the side of a previously drilled hole, as shown in
Fig. 18, there is the danger of the unsupported drill point
This can be avoided
being broken off as it breaks through.
if a plug of material similar to that of the work is fitted to
the first hole, so that the drill point is supported throughout
its travel.
Drilling
on an inclined krface.
Should
an
attempt
be made to drill a hole on an inclined surface, the drill
wit1 naturally tend to travel down the slope, and the
side-strain imposed may break a slender drill or, at best,
it will cause the hole to be drilled out of position.
It is
advisable, therefore, to prepare a flat work surface, either
1.31
by filing, chipping or machining, prior to the marking-out
and drilling operations.
Cross-drilling
Shafts. An operation often required in
the workshop is the drilling of a hole exactly across the
When a jig suitable for this purcentre of a round shaft.
pose is not avaiiable, the following method may be adopted :
a line is scribed through the centre of the shaft, as described
in the set tion on marking-out in Part I, and this line is
CLAMPS HOLDING
CK TO
TABLE
SCIUARE FOF
ALIGNMENT,
OF WORK
__l=(r
Fig. Ig
VEE BLOCK
i 3;1.
continued for Sony distance along the shaft? as represented
in Fig. 1~). A ctm~~~x~
punch mark is then made on this
line tn locate the 1101~at the required distance from the
end of the shaft.
?;c.ut, the shaft is clamped in a V block resting on the
drill tab!c, Mith :‘he scribed diameter line set vertically
by means of a square.
A small crr~tre drill is then used to cnlarg~e the punch
mark and to fi)rm a bearing fix tl,e point of the drill which
ii~llo~~ 10 fi~~rr-n
the cross-hole.
Although a list of tapping
Drilling
Holes for Tapping.
size holes is given in most books of reference, these holes
l\-ill in Mary cases be found too small for general use and
ma). bc the cause of broken taps an? out of line threads.
A method of selecting the correct size of tapping driil
ii,r a particular tap was described in Part I ; briefly, this
corlsists in trying the tip of‘ the taper tap in the holes of
the drill gauge until a hole is found which admits the tap
as far as the line indicating the bottom of the first thread.
If a parallel hole is drilled and tapped, the result will
probably rcsernble the appearance
shown in Fig. 23~,
where it will be sxn ,,4at t~he metal surrounding the hole
has been raised in an irregular burr which will prevent the
proper seating of a component against this surface.
To
avoid this, the hole, prior to tapping, should be enlarged
to the full clearina size for a depth equal to some oneand-a-half threads, as shown in Fig. 20~.
If an attempt is made io enlarge the hole after the
ta.pping operation has been completed, the mouth of the
hole will not be forn,ed concentric with the bore as the
inclination of the threads will cause the point of the drill
to be pushed to on’e side of the hole.
Tapping in the Drilling
Machine.
Although a tap will
tend LOkeep upright in a hole which has ample clearance,
and its squareness with the surface can be checked during
a hand-tapping operation, machine tapping has the advanrage that the tap is entered and guided truly in the work
throughout the tapping operation.
In commercial prac-
tice the tap is mounted in a dril!ing ,nachine or in a
tapping
speciai rapping machine-, and a fi,iction-driven
artachment is used to drive the tap and to prevent breakage
\vhen the bottom of the iiole is rear!ied.
?‘his principle can be readily applied to the drilling
machine with the tap heir! moderately tightly in the ordinary drill chuck. ‘l’he tap is rct.atrci either by pulling
on the tx!lC or, preferably, by turning the spindle by means
of a handle secured to its upper end. The construction of
a llantlle specially designed fw this purpose is ftrlly described in Chapter Six.
As, when tapping in thi:j wa;:, both hands are occupied
in holding the work and ti;;;Gng the machine, the downward pressure required to st&rt the tap can be applied by
means of a length of cord axi..i::hed to the feed lever, and
hauing at its lower end a ioop io form a stirrup for the foot.
Countersinks.
In order to allow screws with conical
heads to lie Slush with the surfze of the work, the screw
holes are recessed with a countt.rsink having its cutting
edges formed to an included angle ofgo deg. The commercial
cutters with four or more cutting lips are iiable to chatter
and form a recess with a rough, waved surface ; and
although better results are obtained by using a very slow
speed, this is not always possible in the case of the small
drilling machine.
If, however, a flat-faced countersink having a singlecutting edge and a guide edge is used, this tendency to
chatter will be prevented.
! 24
Full directions for making a cutter of the-type suitable
for use in the small drihing machine are given in Chapter
Six.
Counterbores
and Pin Drills.
It is a rule in good
engineering practice that where a nut or screw seats on a
component it must do so on a flat surface truly square with
the line of the screw hole.
When, therefore, a rough casting is drilled for the
passage of 2:. bolt, it is essential that, at the same time, the
surface against which the nut bears must be correctly
mac,hincd.
Again, where the work is recessed to receive the head
of a cheese-headed screw, the bottom of the recess must
be formed with a flat surface to afford a proper seating
for the screw head.
These machining operations are u::ually carried out by
means of a tool known as a counterbore: pin drill, or spotface cutter.
Directions for making two types of this cutter are given
in Chapter Six, and reference to the illustrations in that
section will show their usual form.
When using these cutters a pilot hole is first d,rilled~to
fit the central guide p’;g, and after the machining with the
cutter has been completed, the pilot hole is enlarged to its
finished size.
It is advisable to run these tools at a slow or moderate
speed in order to avoid chatter and to enable the depth of
machining to be more readily controlled.
CHAPTER TWO
The Grinding
Head-Driving
the Machine
Electric Grinding Machine-Angular
Grinding Rest-Grinding
Operations-Grinding
Twist %ills.
As it is impossible to do good work with blunt or incorrectly
of installing
propel
sharpened
tools, the importance
grinding equipment and adopting a sound method of
sharpening
the workshop tools can
hardly be over-stressed.
Apart from the minor sharpening
operations carried o>.lt with the aid
of carborundum or oil bench stones, as described in Part I,
the bulk of this work is done on a carborundum wheel
mounted on the spindle of a grinding head.
A simple and inexpensive form of grinding head is
illustrated in Fig. 2 I ,. where it will be seen that the spindle
carries a grinding wheel at either end ; usually, a coarse
wheel for roughing and a fine wheel for finish grinding are
fitted.
The spindle runs in bearings machined in the iron
casting, and a small range of adjustment is provided by
splitting the bearings on one side to enable them to be
closed on the shaft by means of a clamp screw.
Needless to say, precision fitted bearings can hardly be
expected in a machine of this type where the first cost is
low, but if the spindle and bearings are later accurately
hand-fitted by an experienced worker, the machine will
run almost noiselessly even at high speed. A rather more
elaborate form of grinding machine is shown in Fig. 22,
and although the grin,ding rests are not designed for angular
135
Fig.
21
setting when grinding tools on -he side of the wheel, this
could be made good by fitting angular tool rests of the
type described later in this chapter and in Chapter Six.
Driving The Machine
Small machines can be driven
from an electric motor by means of a sewing machine
belt joined with a U fastener, as described in the case of
the drilhng machine.
The.grinding
heads illustrated have a pulley fitted to
the spindle between the two bearings ; this usually emails
driving the machme from a motor or lineshaft situated
either above or behind the grinder, as shown in Fig. 45,
in Chapter Four.
If, on the other hand, the pulley is fitted to one end of
the spindle and a single wheel only is mounted on the
shaft, then a belt drive can be taken from a motor fixed
below the bench.
Where, as Grown in Fig. 46, Chapter Four, the driving
Fig. 22
from abrasive dust either by means of a lig
screen or by the temporary use of a large sheet of cardboard.
If the best results are to be obtained when grinding
tools, it is important that the wheel should be driven at
a surface speed of approximately 5,ooo ft. a imh. in accordance with the following table :
I
5
,3
6)I.--
/
’ 9,000
99500
6,400
4,800
3,800
3,200
The *,ool merchant -41 supply grinding wheels suitable
for ordinary tool grinding in the small wor;tshop, but if
further inform&m
on this subject, or about tool grinding
in gencrai. is sought, reference Mary be made to Sharpening
Small Teals, pubhshed by iZrgus Books Ltd.
The Electric Grinding Machine. The “Black and Decker”
sell-contained
grinding machine,
illustrated
in Fig. 23,
has the advantage that it can be placed in any required
position on the bench, or cn a side bench where the
danger from abrasive dust is well removed from the
machine tools; in addition, its position can be fixed without reference to the requirements of a belt drive.
Two 5 in. diameter grinding ,&heels are attached to
the spindle to provide for rough and finish grinding respectively.
Although the +nding rests fitted are intended for use in
connection with the periphery of the wheel, it should not
be a difhcult matter to make and fit adjustable angular
rests for grinding tools on the side faces of the wheels.
As already mentioned these rests are described here and
also in Chapter Six.
DIVISIONS OF 50
FRO~M O’=-30° EACH
SIDE OF ZERO
jp
ANGULAR
ADJUST-
Fig. 2.5
Although grinding heads are obtainable with grinding
rests incorporated, these rests, -except in the more expensive machines, are generally designed for grirrding tools
on-the periphery of the wheel as in the case of the grinding
machine illustrated in Fig. 22 ; but just as an angular
rest can be made for attachment to the bench, as described
ins Chapter Six, so also can this type of rest usually be fitted
to the machine itself without great difficulty, if the method
of grinding’ the tools on the side-face of ,the wheel is preferred. ,’
142
Apart from grinding twist drills,
the chief use made of the grinding machine in the small
workshop is for sharpening the lathe tools.
Now, this
eperation must be carried out with considerable accuracy,
otherwise the free-cutting properties of the tool may be
impaired or the strength of its cutting edge reduced.
If a new lathe tool or one that has been ground in a
factory is examined, it will be found that the areas ground
to form the cutting edges are flat, uniform surfaces, but
on the other hand, a tool ground by an inexperienced
workman witfrout proper equipment will, in all probability,
show a series, of small ground surfaces crossed by uneven
ridges. The even, flat surfaces in the former case give the
true tool form, and the ridges and hollows in the latter
largely detract from the cutting efficiency.
This difference
of surface finish probably
results
from an angular grinding rest being used in the factory,
and a method of free-hand grinding being adopted by the
casual worker.
The advantages gained when using a proper rest are
so outstanding
that they should not, if possible, be
neglected ; moreover, when attempting
to grind freehand and using the eye and the hand to guide t~he tool,
any small slip may result in much time and labour being
wasted in making good the grinding error.
As has already been mentioned, the use of the side
faces of the wheel is to be preferred for ordinary tool
grinding in the workshop.
When the periphery of a small
wheel is used to grind a tool, the surfaces so formed will
be markedly concave, and where two such surfaces meet
at the tool’s cutting edge, this edge will be undercut and
weakened ; further, not only is it a difficult matter to
adjust the height of the rest to grind an exact angle, but
the setting of the rest will necessarily vary according to
the thickness of the tool.
If, on the other hand, the side of the wheel is used, the
rest can be readily set to grind an exact angle on the tool
irrespective of the tool’s thickness.
Grinding
Optirations.
143
A convenient method of setting the rest is illustrated in
Fig. 24 where it will be seen that a sheet-metal template,
cut to the, required angle, rests on the work table and the
In
upright edge is brought into contact with the wheel.
the drawing the template is shown mounted in a rule holder,
but a rectangular block may be used to maintain the template in a vertical position.
s1oE OF TOOL
END OF IDOL
x)P
SURFACE OF TOOL
Fig. 26
To set the work table., the upper hexagon-headed screw
is slackened, and it may be necessary, at the same time, to
slacken the lower screw to enabli- ‘the gap in the table to
be adjusted to clear the sides of the wheel.
When these
adjustments have been made, both these screws should
be firmly secured to prevent the table from shifting during
the subsequent grinding operations.
It will be noticed that the template is cut to an angle of
The reason
12 deg. at one end and to I I deg. at the other.
for This is that when grinding the tool on the coarse wheel
to form the clearance angle the 12 deg. setting is used, and
this is followed by finish-grinding to I I deg. on the fine
wheel.
In this way little metal will have to be removed at the
final grinding operation, and not only will the whole
grinding process be quickened, but there will be less
danger of overheating the tip of the tool.
Although the question of the form and, the angles at
the cutting edges of lathe tools is dealt with in Chapter
144
Five, it will be advisable here to consider briefly how
angular grinding is employed to form a typical lathe tool.
Other tools vary in form, but the methods used for grinding
their cutting angles are the same.
The stages ir. the finish grinding of a knife tool are
illustrated in Fig. 26. First, the side c!earance is ground
with the grinding rest set to I I deg. ; next, the front clearance angle is formed with the rest in the same position ;
then, with the rest reset to 20 deg. in the opposite direction,
follows the operation of grinding the slope on the upper
surface, or the side-rake angle as it is termed and which
will be explained in Chapter Five.
When applying the tool to the grinding wheel, the tool
must be kept moving in a direction parallel with the sideface of the wheel ; it must not be allowed to dwell and
only light pressure should be used, otherwise it may be
overheated and its cutting properties spoilt.
In spite of advice that is sometimes given, on no account
should the tool be dipped in water to cool it during the
course of the grinding operation,
for this will almost
certainly result in the formation of surface cracks in the
cutting edge, and, when the tool is put to work, particles
of metal will break away leaving the cutting edge blunt or
jagged.
Nevertheless, where much metal has to be removed,
the tool must be allowed to cool during the grinding operation, and this can be hastened by letting the tool lie on a
metal block.
Should several tools have to be ground, it
is better to deal with,each in turn for a short time so that
cooling can take place meanwhile.
The final sharpening operation consists in honing the
tip of the tool to an angle of IO deg. on an oil stone ; this
is carried out with the aid of a stoning,jig, and the process
will be described in the appropriate place in Chapte,.
Five.
Grinding Twist Drills.
Although an experienced workman can, with the aid of a gauge, grind a large drill with
some degree of accuracy, this is far from being the case
145
where a novice is concerned and the drill is of small
diameter.
If the drill is ground so that the cutting lips are of
unequal length or do not lie at the same angle with the
long axis of the drill, then the drill will neither cut a hole
true to size nor will it pursue a straight path.
3
Fig. 27
If, from lack of proper equipment, free-hand grinding
has to be used, some idea of the~hand movements required
” when grinding can be gathered by rolling the conical
face of a large drill against the side of the stationary grind,‘,: ing wheel.
These movements should be practised until
,‘,, ,the tip of the drill can at all times be kept in leve:l contact
with the wheel ; and after making a trial passage of the
drill on the revolving wheel, the tip should be measured
with the rule and protractor to see if the grinding has, been
carried out correctly.
On the other hand, a quick and reliable method of
grinding twist drills is to use a grinding jig in accordance
-.
_ _
with ordinary workshop practice.
,‘A small, accurately made jig suitable for use in, the, small
146
workshop is the Potts drill grinding jig, illustrated in
Fig. 27 ; this appliance will sharpen drills up to # in. in
diameter.
The jig itself is attached to the bench by means of the
base bracket shown in the drawing, and after the spindle
(A) has been set p ara!ie! with the axis of the wheel spindie,
the clamping screw is tightened.
To give the correct
back-off or clearance angle, the calliper jaws (C) are set
to the diameter of the drill shank.
Next, the spindle (A) is moved towards the wheel until
the drill carrier (D) is just clear of the side of the wheel ;
the wing nut (E) is then tightened.
The drill is then placed in the jig, as shown in the
drawing, with one lip in contact with the lip gauge attached
to the carrier (D).
When the grinding wheel has been started, the drill is
fed towards the wheel by means of the feed screw shown at
the extreme right of the drawing. The grinding operation is
then carried out by swinging the jig about its pivot (H).
Both lips of the drill are ground in this way, with the
same setting of the feed screw, until they are evenly ground
over the whole of their surface,s.
Some makers of both belt-driven and self-contained
electric grinders supply twist-drill grinding jigs for attachment to their machines,
but when purchasing
these
appliances it is advisable to make sure that they will deal
with the smallest drills that are likely Taobe used.
General Description-Types
of Small Lathes
--Methods
of Driving-Lathe
Accessories
--Lathe Maintenance.
As will be seen in the drawing in Fig. 28, which represents
a small lathe of the type generally used in the small workshop, the modern lathe is a highly developed machine
capable cf a wide range of work in
THE LATHE
addition to ordinary turning operations.
The smaller components shown in
the drawing are named so that they can be readily identified when referred to both he re and in later chapters.
The Bed. This is the main casting on which the other
:, components are assembled, and on its proper design and
construction the accuracy of the lathe as a whole will
” largely depend.
When the bed is support,ed on two widely-spaced feet
it may be distorted if bolted down to an uneven surface
such as the top of a wooden bench.
This can be readily
demonstrated by applying a test indicator to the free end
,of a long bar held in the lathe chuck and then tightening
the holding-down bolts ; if the surface of the bench is
untrue, the test indicator will record the deformity imparted
to the bed.
Should the bed be distorted in this way, the lathe will
not machine truly, and packing strips must be placed
under the bed feet to level the surface on which the lathe
stands.
The bed of the lathe illustrated has what amounts to
a single foot-piece, and, here, distortion is much less likely
to arise, When bolting down, as this part represents the
most rigid’ p&ion of,the bed.
147
BACK GEAR
GUARD
TOOL
CLAMP
FP.CEF.IA7-E
ITRE
LEVER FOR
CLASP NUT
EV’,P.GEME!~!T
TAILSTOCK
BARREL 8
CENTRE
/
/
LFAIXCRFW
149
On the upper part of the bed an accurate slide-way is
machined, composed of two shears, as they are termed ;
this carri.es the headstock and the tailstock in true axial
alignment and, at the same time, the saddie and the
tailstock are guided on a straight path as they are moved
along the bed. The bed shears fail short of the headstock
leaving a gap to ailow for turning work of large diameter.
Tb - Headstock.
This is a rigid casting
fitted with
1set
gs in which the lathe mandrel rotates.
Different
types of bearings are used for this purpose, but plain pardIe!
bearings are, in general, to be preferred.
In order to provide the low mandrel speeds required for
some classes of work, a back gear, not unlike a motor car
gearbox, is fitted, consisting of a gear wheel reductl’on drive
between the belt pulley and the mandrel.
The lathe has, therefore, six speeds : three direct, and
three indirect through the back gear ; these are arranged
in even steps from the lowest to the highest mandrel speed.
The Saddle.
As shown in the drawing, the base or
sole plate of the saddle, which is guided by the shears of
the lathe bed, carries a cross-slide on its upper surface.
;:, This slide has a travel of several inches and is controlled
” by means of a feed-screw fitted with an operating handle
and an index. The index is divided into thousandths of an
inc% and is adjustable so that it can be set to the zero position when turning work to an exact diameter.
Bolted to the cross-slide is the top or tool-slide which
aiso has an index fitted to its feed screw. The slide can
be set to any required angle by means of its graduated
scale, and in this way it is used for forming bevels or turning
short tapers.
A vertical plate, called the apron, is attached to the front
of the saddle sole plate ; this carries the quick or handtraverse gear which errgages the toothed%ack bar attached
to the front of the bed. The apron has also attached to it
the divided clasp-nut with its operating gear which closes
the nut on the leadscrew and thus pkovides the normal
feed for the saddle.
1,
The Tailstock.
The body of this component is usually
formed in two parts : a sole plate to engage the slides of
the lathe bed, and an upper portion capable of being set
over across the line of the bed to enable tapers to be turned
V?hen the
on work mounted between the lathe centres.
tailstock has been set either centrally or to one side, the
two portions are secured with a clamp bolt.
The sole
plate is secured to the bed by means of a quick-acting
clamp and locking lever.
Fig. 29
The tailstock barrel, which receives support from the
whole length of the upper part of the tailstock casting, is
secured in place by the action of a clamp and locking lever
whenever work is mounted between the lathe centres.
To facilitate drilling holes to an exact depth, the tailstock
barrel should be graduated.
The Feed Gear.
Where a separate feed shaft is not
fitted, the saddle is traversed along the lathe bed by means
of the leadscrew when engaged with the clasp-nut attached
to the saddle apron.
A handle is attached to the right-hand end of the leadscrew to enable the saddle to be fed by hand when turning
short lengths ; in addition, the hand wheel carrying this
handle is fitted with a: index graduated in thousandths
151
of an inch to permit of an exact length being machined
on the work.
When an automatic feed for the saddle is required, the
leadscrew is turned by the mandrel through a train of
gear wheels mounted on the lathe quadrant, or banjo as
it is sometimes called.
The relative speeds of the mandrel and leadscrew depend, of course, on the size of the wheels used, but reference
to the makers’ chart will show the wheel trains required
for either screwcutnng or for ordinary turning.
To enable the saddle to be traversed either towards or
away from the headstock, a tumbier gear, consisting of a
secondary gear train, is sometimes fitted to the mandrel ;
this has the further advantage of providing a neutral or
no-drive position in addition to the forward and reverse
movements.
Lathe Types.
There is no need to give, here, a detailed
description of the. lathes briefly referred to below. for full
information in each case, together with illustrations showing the constructional details, can be found in the respective
manufacturers’ catalogues.
The Perfect0 Lathe.
illustrated in Fig. 29, is of robust
design having an anvil bed that enables the purchaser to
mount the Lathe on the bench without fear of distorting
the machine and impairing its accuracy.
The Perfect0 Lathe is available in three mcd&The
basic machine is not provided with a driving motor or
self-contained
countershaft whilst the other two models
have motor driving units supplied as standard. The more
has adequate
expensive model, seen in the illustration,
protection by guards fitted over the change wheels and
final drive belt, whilst the intermediate model has a guard
over the mandrel belt only.
The centre height of the Perfect0 lathe is 34 inches
(85.7 mm) and its capacity between centres 16 inches
(406.7 mm). The mandrel is bored 5/8 in. diam. (15.9 mm)
allowing the user rather more scope than is sometimes
obtainable in a small lathe.
Fix.
:jt)
in Fig.
30 has been designed to provide the user with a simple
machine tool at a co.mpetitive price. The standard equipment included is comprehensive and there is a range of
additional fitrnents obtainable that will greatly extend the
versatility of this very useful machfine.
The illustration shows the lathe mounted on its stand
and equipped with self-contained
motor drive through
V-belts.
This
machine
has been
The Myford
ML7 Lathe.
more recently designed and embodies many up-to-date
features which will be found particularly useful by the
model engineer, and also by those undertaking other forms
of mechanical work where a ,wide range of adaptability
The design includes the provision l)f a robust
is essential.
and rigid mandrel which enables heavy cuts to be taken
A very extensive range of accessories and
when required.
including gear cutting and taper
fittings is available,
turning attachments.
As shown in Fig. 3 I a very effective form of self-contained
motor-drive is fitted.
Formerly,
the alternative
to foot
The Lathe Drive.
The
Myford
MLIO Screwsetting
Lathe, illustrated
153
power was a belt-drive taken from a power-driven countershaft, but nowadays, manufacturers usually supply their
lathes with a self-contained
electric motor driving-unit,
fitted either as a standard part of the equipment or at an
extra cost.
The ML7 lathe illustrated in Fig. 31 is fitted with a
driving unit of this type attached to the rear of the bed ;
the constructional
details of the device are shown in
Fig. 12.
Fig. 31
The elect& motor is mounted on a swinging platform
to allow the tension of the motor-driving belt to be correctly
adjusted.
This belt d rives the countershaft seen at the
top of the figure, and the swinging bracket carrying this
shaft is controlled by a ball-ended lever for releasing the
belt tension when changing speed.
In addition, the position of this bracket can be adjusted
to set the belt tension correctly for the final drive to the
lathe pulley.
As will be seen, a neat, well-fitting, sliding cover is
provided to guard the belts.
7..
Other methods
of driving the lathe when installed in
the ~vorLshc>.p wi)! he described in the next chapter,
Althou&
the makers furnish their
lathe
Plccessories.
lathes w+th certain
accessories,
the purchase
of others is
essential b&x-e the lathe can be put to l,vork on the more
however,
usual
turning
operations
; some accessories:
such as a tool turret, whi!st not indispensable,
certainly
do add to the pleasure and convenience
of using the lathe.
Fig.
32
i56
to centre the work accurately or to set it in any other
position required.
Directions for setting work in this type of chuck are given
in Chapter Five. As the chuck has four jaws it will hold
very securely even when the work is of irregular shape.
When changing the jaws to give inside or outside gripping, they are merely reversed in their slots, for each is
actuated by its own feedscrew.
Either of the two mandrel chucks described can be fitted
to the tailstock, if required, by means of the ndaptcr shown
in Fig. 36, which has one end formed to engage the taper
in the tailstock barrel, and the other rnd is ;I replica of thcb
screwed nose of the mandrel.
The Drill Chuck.
Whell drilling
work, llcld
in the
mandrel chuck, by means of a drill mounted in the tail-
ted 011 a doublcIf, however, the drill is held in thcx
mandrel chuck and the work is supported and l’cd fc)r\v-;~rd
V-grooved
fitting will locate a round Ijar IO ~n;tl)l~ :I 1~1~
e usual single-tool
As four tools of diKcrc;lt
clamp littcd to the
forms, can, at the same lime,
Fig.
37~
is avoided, for the turret has merely to be rotated to bring
any tool required into the correct position.
To facilitate accurate repetition turning of parts, a
ratchet gear locates the turret at any one of eight stations,
thus enabling the tools to be accurately reset to the work
as they are successively brought into use.
The clamping lever shown in the photograph secures
the turret firmly in place after its position has been set.
The Fixed Steady.
When clamped to the lathe bed, as
illustrated in. Fig. 40, this appliance is employed to support
Fig-, 37~’
159
the overhanging end of the work, such as a long shaft,
held in the mandrel chaick. This becomes necessary wher
the work has to be faced and axially drilled as described
in Chapter Five.
The steady is fitted with three adjus~table, bronze jaws which are set to make contact with the
work and thus afford it a supporting bearing.
As its name implies, this form
of steady, which is illustrated in Fig. 41, travels in the
wake of the tool and gives support to the work in both a
vertical and a horizontal
direction
against the tool’s
cutting thrust.
The
Travelling
Steady.
KY. 40
Either hardened steel or bronze jaws are used, but the
latter may be preferred as they do not damage the finished
surface of the work.
It is essential that the construction
should provide for fixing the pressure pads securely,
otherwise they may become displaced during the course of
the turning operation.
Hand Rest.
The rest illustrated in Fig. 42 is employed
when turning work with hand tools, as described in Chapter Five.
Fig. 41
Fig. 42
162
For this purpose, it is bolted to the lathe cross slide,
and after the rest itself has been adjusted to the correct
height to suit the tool used, it is secured in place by tightening the wing nut shown in. the figure.
The first essential in looking after
Lathe Maintenance.
a lathe is to keep the working parts clean and well oiled.
Not only should the slides and other parts be kept free
from metal chips, but when not in use, the lathe should
be covered with a cloth or sheet to exclude the dust that
is so harmful to the working parts.
A small brush can be used for clearing the chips from
the slides, after which they should be wiped with a clean
rag and then lubricated.
Medicinal paraffin is a useful
lubricant for the lathe bed and slides as it does not become
sticky and form a varnish-like film on the lathe parts.
Where oil is used, any dried deposit can be readily removed
from the metal parts or paintwork with the aid of methylated or surgical spirit.
A good quality thin oil should be used for iubrir?ting
the mandrel and other bearings.
The leadscrew and the feed screws of the slides should
also receive periodic cleaning .and lu.brication.
As the mandrel bearings of a new lathe become beddedin, they may require adjustment to remove any play both
in the journals and in the thrust bearing ; this should be
carried out in accordance with the instructions issued by
the manufacturers.
The gibs fitted to the saddle and slides must also be kept
in proper adjustment to eliminate play, but over-tightening
of the slides should be avoided as this causes need!ess wear
in the feed mechanism ; moreover, a well-fitted slide
should move quite freely and without play if given only a
very small working clearance when tire gib is adjusted.
The thrust nuts fitted to the feed screws of the slides
should be kept in adjustment so that excessive backlash,
which would interfere with the proper working of the feed
,mechanism, is not allowed to develop.
CHAPTER FOUR
Setting
out the Machine
Tool
BenchLine-Shafts and Countershafts-Direct
Drive
from
Electric
Motors - Installation
of
Motors.
IN previous chapters the driving of the individual machine
toois has been considered, but where the tools are grouped,
as often happens in the small workshop, and more particularly perhaps in the indoor workshop, then it is advisabler to adopt a definite plan in
ACHlNE
arranging the machines and their
THE
drives so that they can be used to
P
the best advantage.
As the question of economy as well as convenience may
:
:;m,arise, in some instances a sirrile electric motor may be
Where a room
;: made to drive more than one machine.
,“’ within the house is fitted out as a workshop, compactness
may
be desirable both to save space and to maintain a
idy appearance.
In these circumstances.
it is not unusual to find the
,‘, ,rnachine tools grouped on a single bench with sufficient
space left for installing the vice and carrying out hand
work.
A convenient form of layout is illustrated in Fig. 43. It
shows the lathe and drilling machine mounted on the
bench and ‘coupled to a common lineshaft driven by a
single motor,1
When the’ oper,ator works alone and only one machine
at a time is used, a 4 h.p. motor will generally be found
sufficient for \driving a 3& in. lathe, unless high speeds are
required and \the lathe makers recommend the fitting of
a larger motor.
\I
I
:
163
164
Although the lineshaft can be mounted to run in plain
bearings, ball-beari,ng shaft brackets are strongly recommended for this purpose, as frictional losses are greatly
reduced and lubrication
and other attention
are then
required only at long intervals.
Shaft brackets of the plain or ball-bearing type, as well
as the necessary pulleys and shafting, are standard commodities
and can normally
be obtained
from
the
tool merchant.
Lathe makers usually recommend
that the countershaft speed should be some 400 r.p.m. ; this figure must,
therefore, be taken into account, when fitting the belt
pulleys, to ensure that the reduction ratio obtained will
provide the correct countershaft speed.
If the motor installed runs at, say, 1,200 r.p.m., the
ratio of the diameters of the pulleys used should, therefore,
be I : 3, which means that if a 2 in. Iulley is fitted to the
motor, a 6 in. diameter pulley is needed on the countershaft or lineshaft.
When V pulleys are used in conjunction with a Ir belt,
0A
166
these pulley sizes refer to the pitch diameter which is
measured from the middle line of the belt’s thickness as it
lies in the groove of the pulley.
This is i!lustrated diagrammatically
in Fig. 44~, where
the belt is shown bedding deeply into the pulley.
The pitch diameter or effective diameter of the pulley
is then represented by the arrow-headed
dimension line
which indicates the diameter taken up by the centre line
of the belt when lying in the pulley groove.
Where the belt runs on a large plain-faced pulley, as
shown in Fig. 44~, the pitch diameter of the pulley is again
measured
between
two diametrically
opposite
points
lying on the belt centre line.
In the arrangement illustrated in Fig. 43 the lineshaft
takes the place of a separate countershaft to save complication and expense, and the machines are started and stopped
by using the switch controlling the electric motor.
Either
machine can be temporarily put out of action by removing
its belt from the driving pulley and then suspending the
belt from a hook to keep it clear of the driving shaft.
It will be seen in the drawing that the position of the
motor necessitates a very short belt drive ; this is best
catered for by using a V belt in conjunction with a V
pulley fitted to the motor shaft, but the large driven pulley
should have a plain, flat face as the frictional contact
obtained will be ample for an efficient drive.
The shelf
on which the motor is amounted will also provide space for
storing the lathe chucks and other accessories.
The vice is fitted directly over one of the bench legs in
order to afford a rigid mounting, and although some space
has been allowed for hand work, this might well be increased by lengthening the bench for large work.
It is intended that the complete bench assembly should
be placed in a good light near a window and, when artificial
lighting is needed, an ad:justable lamp bracket can be
attached to the motor shelf to allow the light to be swung
into a position to illuminate either of the machine tools or
the bench vice.
167
It will be noticed that a grinding machine has not been
fitted to the bench, for in a compact assembly of this form
it is usually preferable to mount the grinder on a separate
shelf or small bench in order to keep abrasive dust well
away from the machine tools.
A rather more ambitious arrangement is illustrated in
Fig. 45, where it will be seen that a larger bench is used
which not only provides, more space for hand work, but
at the same time allows the grinding machine to be mounted
in a safe place on the bench top.
More floor space will, of course, be needed, and it is
intended that the far end of the bench, as seen in the drawing, should be placed towards the window so that the
operator has room to work and use the tools installed on
either side of the bench.
The grinding machine is mounted at one end of the
bench and a plywood baffle or screen is fitted to protect
the lathe from abrasive dust.
Although, for the sake of clarity, it is not shown in the
drawing, a metal dust shield should be fitted to the grinder
itself to limit, as far as possible, the dispersion of emery
dust and afford greater protection for the machine tools.
The grinder is directly driven from the motor shaft by
a pulley of the correct diameter to drive the grinding wheel
at the proper speed.
As in the previous example, the
lathe a.nd the drilling machine are driven from either end
of the lineshaft which may, in addition, carry a pulley for
driving attachments, such as a miiiing device, fitted to the
lathe saddle ; but it should be made clear that the amount
of power that can be transmitted in this way is limited by
the whip of the shaft when under load and the distance of
the pulley from a supporting bearing.
In order not to confuse the drawing, a stretcher or tiebar has been omitted, but if this is fitted across the tops
of the upright bench members, the rigidity of the assembly
will be increased and, in addition, the tie-bar will form a
convenient point of attachment
for the bracket of the
adjustable lamp used to light the bench.
166
drill
There is much to be said for providing the extra space
shown in the drawing, for it will be apparent that on the
left side of the bench ample room is left for installing a
hand-shaping machine, or a larger drilling machine with
self-contained drive.
lathe with self contained
countershaft,
4-I
Fii
ill
2
motor
/
motors
Fig. $6
The arrangement illustrated in Fig. 46 is designed to
afford the maximum of free space on the top of a small
bench by making the drives of the machine tools as compact
as possible.
The lathe is driven by a self-contained motor drivingunit of the type now supplied by the makers of many wellknown lathes.
This unit has the advantage of taking up but little bench
space as it requires no separate countershaft or supporting
,,,
170
The lathe with its drive-unit
can thus be
uprights.
mounted on the bench exactly where required and without
reference to any outside source of drive.
The motor driving the drilling machine is mounted, as
described in Chapter I, below the bench where it does not
encroach on the bench surface and, moreover, it is there
well-protected
from chips although
readily removable
when required. The belt passes through a hole cut in the
bench top and leads directly to the guide pulleys fitted to
the bead of the drilling machine.
The grinding machine is also driven by a motor fixed
to the under-side of the bench top. These motors can be
easily removed for cleaning and lubrication if they are
attached to a wooden base which slides in runners fixed
to the under surface of the bench top.
Although, to simplify the arrangement of the drive, a
grinding machine with a single wheel is used ; as mentioned in Chapter II, a second grinder can be installed in
order to provide both a coarse and a fine wheel for tool
In this case, either the bases of the prinders
sharpening.
are secured to th,e bench by means of bolts fitted with wing
nuts, or the bases are made to travel in slides to enable
either machine to be moved into place when needed.
The motor is, here, in a convenient position for driving
any other machine that may be brought into temporary
use, such as rotary cutters and polishing wheels attached
to a flexible shaft carrying a driving pulley.
Although a bench of comparatively small size is shown
in the drawing, it will be seen that space is available for
hand work or for mounting additional tools.
It sometimes happens that, owing to lack of space, a
machine has to be installed in the workshop in a position
where a drive from the lineshaft or from an adjacent
motor cannot be easily arranged.
The best solution of this difficulty is to drive the machine
from a motor specially installed for the purpose ; but,
on the other hand, the expense may seem hardly warranted
when the machine in question is but rarely used, and there
i7l
,,,,, ,i,~ ,~,,~,,
,,,,: : .,: ,~,~,
,,,,
,,
,,‘,
~,‘,’
,,
112
is also the possibility th& at some future date the tool may
be replaced by a machine with a self-contained motor
drive.
Nevertheless, a drive from some distant point can usually
be arranged with the exercise of a little ingenuity, and the
manner in which this difficulty has been overcome in a
shed workshop is shown in Fig. 47.
A long belt-drive is taken from the lathe countershaft,
installed near the roof of the building, to a second countershaft attached to a beam at the other end of the workshop.
The belt is guided on its course by means of suitabiy
placed jockey pulleys.
The final drive to the fr in. capacity drilling machine
shown in the drawing is by a chain and sprockets ; this
form of drive is used to give the necessary speed reduction
and to avoid the slip which would inevitably occur if a
short belt-drive were employed in this situation.
Two long cords, attached to the belt shifting gear of
the lathe countershaft, are brought to the drilling machine
by passing over guide pulleys ; these are used for starting
and stopping the drill.
Moreover, as an ordinary measure of safety, a switch
that can be operated hy either hand should be fitted near
every electrically-driven machine to enable it to be stopped
instantly in an emergency.
GiiAP’l’EK
FIVE
Instruments Lathe Tools - Measuring
Chuck
Work-S!iding-Surfacing-Boring
-Use
of the Faceplate-Turning
Work
between Centres-Mounting
the WorkUse of Steadies-Boring
Work
on the
Saddle-Drilling
from the Tailstock-Depthdrilling-The
D-bit-Tapping
and Dieing
-Screwcutting-Turning
with Hand Tools.
operations
are
any
turning
Before
described, it will be advisable to consider the formation
and sharpening of the lathe tools in greater detail, for on
these facto:~s will depend almost entirely the success of
the machining processes described later
in this chapter.
Moreover, even if a
OPERATING
THE LATHE
set of tools is purchased sharpened
and ready for use, these will inevitably
become b!unted and will need to be resharpened in the
same methodical manner as that employed in the first
instance by the toolmaker.
When grinding methods were described in Chapter Two
it will be remembered that the use of an adjustable, angular
grinding rest was strongly advocated and the resort to
free-hand grinding was deplored.
In this chapter is was also shown how the commonly
<used angles could be readily ground at t~heend of the tool
to form the cutting edges.
It will now be advisable to consider in greater detail the
purpose of these angles and to indicate the names by which
they are generally known.
The Knife Tool.
The most generally useful and therefore the ,lathe tool most used in the small workshop is the
right-hand&d knife tool, shown in Fig. 48, where the fofm
Lathe
Tools.
173
174
angles are named and their values for ordinary work
specified.
These angles, which fall naturally into three classes
according to the purpose they serve, can be described as
clearance angles, rake angles, and relief angles. Clearance
angles are those which keep the tool clear of the work
aftter it has passed the cutting edge, so that only the line of
the cutting edge makes contact with the work. The rake
angle represents the obliquity of the cutting surface presented to the work and on which the cuttings impinge.
Relief angles are formed to reduce the extent of the cutting
edge in contact with the work to allow the tool to cut freely.
Clearance
Angles.
These are given to allow the tool
to cut and not merely rub against the work. As shown in
Fig. 48~ and B, it is necec-,ary to provide clearance both
at the front and at the side of the tool, for the cutting edges
come into contact with the work in both these situations,
Clearance angles of IO deg. can be used for all ordinary
purposes, but in any tool of slender form this should
be reduced to maintain the strength of the tool’s tip.
The principle underlying the provision of clearance is
common to all tools, and its application should be clearly
understood to enable tnols of various forms to be sharpened
correctly.
L&he tools should be examined’frequently
to make sure
that the cutting edges are in gcod order, because when the
clearance angles become reduced or obliterated by wear,
the tool’s cutting efficiency will be imbaired and the finish
of the turned work will suffer.
Rake Angles.
The rake angles provided in a knife tool
are shown in Fig. 48~ and c, and it will be apparent that,
in this case, the side-rake is the more important as it ensures
that the steeply sloping surface behind the cutting edge
allows the metal to be easily sliced off in the direction of
the tool’s travel.
The front rake, that is to say the slope from the front
edge of the tool towards its shank, is of less importance in
a knife tool, which normally cuts but little on its front
175
edge, and it is therefore often omitted as in Figs. 48~ and B.
One advantage of dispensing with the front rake is that
the height of the cutting edge does not decrease when the
front of the tool is regrolund.
@
100 top
k ,c)oL-front
clearance
rake
+
Fig. 48
A side-rake of 20 deg. in a knife tool will ensure freecutting in mild steel, but both this and front-rake are
either much reduced or omitted for machining brass in
order to prevent the tool from digging into the work.
When a tool such as a parting ,tool is used to cut on its
front ,face, front-rake is given where the ,to,ol is made for
,,
176
-A
,left- hand knife opposite
to above
,?
”
_I~
knife (riqht-hand)
hand
parting
for brass
no
lhreddinq
top
r&v
100
50
.-I--
machining steel, as shown in the drawing in Fig. 4gc,
but, as before, top-rake must be omitted in a tool formed
for cutting brass.
Relief Angles.
In ;Ez drawing of the knife tool in
Fig. 4gc, it will be seen that the front cutting edge slopes
sharply away from its point of contact with the work ;
this ensures that only a short length of the front edge comes
into contact with the work surface, and any tendency to
chatter is thereby reduced.
In practice, it will be found that the less rigid the work
being turned, the narrower must be the front cutting edge
If the extreme tip of the tool
if chatter is to be avoided.
is slightly rounded, a better finish on the work will result
both when the tool is traversing along the work or taking a
facing cut across it.
From ,,what has been said regarding tool forms, the
177
purpose of the various angles and tool shapes represented
in the drawings should now be clear, and no difficulty
should be experienced. when sharpening these tools or
others intended for special purposes.
Finally, the importance of keeping the tools really sharp must be stressed,
for on this will depend very largely the quality of the work
turned out.
An oilstone slip can be employed to give the final finish
after grinding, or to restore the tool’s edge a&r it has had
a little use. It is, however, difficult to avoid rounding the
cutting edges when using the oilstone free-hand, and it is
preferable to employ a jig or guide block for this purpose.
An easily made stoning jig with a wooden base and
steel side pieces is illustrated in Fig. 50. The base should
be clamped to the bench top, and the stone is guided by
Fig.
50
,,:
,,,
178
the side-members as it is moved to and fro across the end
of the tool held in place with the fitigers. The doubleended guide members allow an angle of either 5 or IO deg.
to be stoned on the tool’s tip.
The drawing shows the front clearance of a parting tool
being stoned to 5 deg., and if the tool is held in contact
with the side-member, this will ensure that the front edge
is formed at right angles across the tool.
Those who desire further information
on the subject
of grinding and stoning lathe tools may refer to Sharpening
Small Tools, published by Argus Books Ltd.
Material
for Lathe Tools.
Formerly, lathe tools were
hand-forged from tool-steel to the rather elaborate shapes
then in common use even in large workshops.. In some
patterns the ends were bent over to form a swan-necked
tool which was difficult to grind accurately as it would not
lie flat on the grinding rest.
Nowadays, it is more usual to use tools of simple form to
enable accurate grinding of the cutting edges to be readi1.y
carried out ; in addition, tough alloy steels with enhanced
cutting qualities are now generally used even in the most
modest workshops.
The Eclipse brand of super high-speed steel is availabIe
in short lengths and in sizes suitable for use in either the
tool-post or the four-tool turret of the small lathe.
This material is suppiied with the ends obliquely ground
to save heavy gri.nding when shaping the tool tip, and as
the steel is ground flat on all its sides, it will lie evenly on
the grinding rest and accurate forming of the cutting
edges is facilitated.
Two instruments
are comMeasuring
Inswuments.
monly employed in lathe work to ensure accuracy of
machining as well as to save time ; these are the screw
micrometer for r;naking exact measurements of the length
and diameter of components, and the test indicator used
for setting and aligning work in the lathe.
This instrument is shown in Fig. 51,
The Micrometer.
and its:, component parts ,~are’,lettered to make clear the
,,
I-::,,;.:“,,,,
“;,,
,,,,
‘,,
179
construction and method of u&g.
It will be seen that a
thimble A, attached to the screwed spi,ndle B, can be
turned with the fingers to advance B towards the anvil C.
When these two surfaces are brought into contact with the
work lying between them, their distance apart, and SO the
diameter of the work, can be read on the scales engraved
on the thimble and on the sleeve, as shown in the draying.
The spindle, where it lies within the sleeve, has a fine
thread of 40 t.p.i., so that for each turn of the thimble the
Fig.
51
le advances
1140 in. (0.025 in.), as denoted on the
The bevelled edge of the thimble is
d into 25 equal parts, and one division of this scale
re, equal to 1125 of a turn of the spindle or 1140
As an
5 in., which is one thousandth of an inch.
f how to read the micrometer, reference to the
” one large division, which equals four smaii divisions of
25 thousandths, or 0.1’ in., and in addition, a further small
division, making a total of 0.125 in. The thimble scale
i8G
The micrometer is a finely-made but delicate instrument,
and if its accuracy is to be preserved it must be carefully
treated.
On no account should it be forced on to or off the work
being measured, and when not actually in use it should
be placed on a clean surface and where it cannot be
damaged by other tools or exposed to metal cuttings.
Although internal micrometers are available for measuring the diameter of holes or bores, the external micrometer
described can be made to serve this purpose in the small
workshop by setting the internal callipers to the bore, and
then using the micrometer to measure across the points.
dial
test
indicator
lock
for swivel
adjustment
locating
pins
\
,,
,,
,,
181
Fig. 53
The more expensive form of this
:,:, instrument, the dial-test indicator, is illustrated in Fig. 52,
and here it is shown attached to the pillar of a base mounting, but it can, if required, be secured either in the chuck
or in the tool post of the lathe.
When the contact point,
which usually has a range of movement of & in., is pressed
‘against the work, the indicator hand records this movement
‘~, in thousands of an inch.
Where the instrument is clamped in the tool-post with
its point in contact with a component mounted in the
lathe, ,any eccentricity of the work will be indicated when
the part is revolved by hand.
An attachment with a pivoted lever can be used with
the instrument for setting the work from the internal
surface of a bored hole.
A much less expensive pattern of test indicator, named
the,‘TJnique”
and illustrated in Figs. 55 and 54, was once
The
Test
indicator.
182
This well-made and serviceable instrument, in spite of
its smaller range of movement,
proved adequate
for
carrying
out all the work-setting
operations generally
encountered in the small workshop.
As will be seen in
the drawing, it can readily be clamped to a lathe tool or
to a piece of material secured in the lathe-tool post. A
window is provided in the base,~portion carrying the scale,
to allow the position of the pointer to be read from either
side of the instrument.
As in the previous example, a
lever attachment, shown in Fig. 54, can be fitted to enable
the work to be set Corn an internal surface.
TNL
UNIQIJL
When
the
lathe is used to
machine a component, three questions arise which have to
be settled at the outset, namely : the lathe speed ; the
rate of feed ; and the depth of cut.
In commercial undertakings output is
Cutting
Speeds.
by running the machines
at the highest
maintained
economic speed and by providing, where necessary, a
system of forced lubrication for the cutting tools. In the
small workshop, however, both this urgency and the
special equipment are usually lacking.
High speeds, used with a normal depth of cut, also have
the disadvantage that they cause heating and distortion
of ,the work, as well as morerapid’ blunting’ of, the lathe
,tools.
Turning
Operations.~
,,,,,
,,
Although a surface speed of the work as high as 120 ft.
per min. can be used when turning mild-steel, the ordinary
lathe user will generally find it better to restrict the work
speed to between 50 and go ft. per min. When machining
cast-iron, these speeds should be halved, but doubled for
turning brass and alummium.
As the circumference of a I in. diameter round-bar is
approximately
4 ft. in length, it follows that to attain a
surface speed of 50 ft. per min. the work must revolve at
200 r.p.m., or 320 r.p.m. for a surface speed of 80 ft. per
min. The slow direct gear should, therefore, be used in
this instance, but if the diameter of the work is reduced
to a half, the lathe speed can then, of course, be doubled.
Rate of Feed.
If the feed is too coarse, or the cutting
edge of the tool in contact with the work is tot narrow, a
spiral groove similar to a fine screw-thread will be formed
on the surface of the work ; but as chatter and other forms
of inaccurate turning must be avoided by keeping the edge
of the tool narrow, it follows that it is the rate of feed that
must be adjusted to give a good finish to the work.
A feed of between 200 and 300 turns of the mandrel
for a feed of I in. will generally be found most suitable
for light accurate turning.
Depth of Cut.
When a deep cut is taken with a normal
rate of feed, not only will both the work and the machine
be heavily stressed, but the heat engendered will cause
‘further distortion of the work.
Roughing cuts for the quick removal of metal are, of
course, permissible, but, except to save time, it is as a
rule preferable to take two cuts of medium depth rather
than a single heavy one.
The depth of cut to apply in any particular case will
be learnt by experience and will depend, in part, on the
rigidity of both the machine and the work. The finishing
cut to bring the component to size should be limited to
a few thousandths of an inch, in order to leave a smooth
surface and ensure accuracy.
~~eti
surfacing, that is to ,say taking a facing cut across
the work, even finer feeds can be employed, and the use
of an automatic surfacing feed is here an advantage.
Use of Chucks.
It will be found that most of the work
carried out in the small workshop consists in. turning parts
held in the chuck but unsupported by the tailstock centre.
The selfcentring
chuck may, as a rule, be expected to
hold material within some two thousandths of an inch of
the true centre, but if the chuck is worn or has been strained
this error may be much greater.
Where a piece of work, without being removed from
the chuck, is turned, drilled, bored, and then parted off,
it matters little if the material is mounted somewhat offcentre, for the accuracy of the machining of the various
surfaces in relation to one another will be unaffected.
If,
however, the work is remov&fiom
the selfcentring chuck
and then rechucked
by one of its turned surfaces, any
subsequent machining will be out of line with the previously turned parts ; also, the amount of this error will
depend on the chuck’s lack of truth.
Although it is sometimes possible to make the chuck
hold truly by using a packing on one of the jaws, it will
often be found that the correction is required at some
point lying at an unequal distance from two of the jaws ;
moreover, the problem is further complicated when the
chuck’s error of holding varies with the position in which
the jaws are set.
Setting Work
in the Four-jaw
Chuck. Thesedifficulties
of untrue centring can be overcome by using the four-jaw
independent
chuck, which ensures that parts can be
chucked or rechucked to run truly.
Although an experienced
worker will set the work
remarkably quickly, it is advisable for the novice to adopt
a methodical way of working from the start, in order to
save time and effort and to,ensure that each adjustment of
the chuck brings the work nearer to the centre.
In the
first place, the guide circles turned on the face of the chuck
should be used to set the jaws holding the work nearly
oentral.
If a tool mounted in the tool-post is then brought
,“,
185
close to the part while the lathe is turned by hand, the
position
of any eccentricity will readily be seen.
When
the gap between the tool and the work is at its narrowest
point,
the jaw farthe% from the operator is slackened and
the opposing
jaw is tightened.
This procedure is continued until the work appears to run truly.
A piece of
chalk held to the work while the lathe is revolving will
then mark any high spot, and the chuck is reset accordingly.
Fig. 55
To obtain real accuracy of centring, the test indicator
is mounted in the lathe-tool post, and its button is brought
into contact with the work while the lathe is slowly turned
this will enable the smallest error of centring
tor is IO thousandths, then the work should be set-over
,half this amount, or 5 thousandths ; this procedure is
with reference to an internal surface in a similar manner,
if the lever attachment is fitted to the indicator as previously
Wh~en the work has to be centred in the chuck with
reference to a previously drilled centre hole, the tailstock
186
drilled centre in the work, and the centre formed in the
plunger at the other end of the device is applied to the
tailstock centre ; the tailstock feed is then used to press
the plunger inwards against its spring. The point of the
test indicator is next brought into contact with the centre
finder close to the work ; and when the chuck is turned
by hand, the eccentricity of the wobbler is indicated and
then corrected as in the previous example.
When centring a part with reference to its bore or to
a drilled hole, a plug can be fitted to the bore and then
centred with the test indicator ; if the plug has a truly
formed centre hole, this hole can be centred by means of
the wobbler.
Turning
Work
in the Chuck.
Here, the work is held
in either the four-jaw or the self-centring chuck and the
turning and other operations are carried out without
support being given by the tailstock.
To illustrate the
methods employed, the machining of the smail part shown
in Fig. 56~ will be followed step by step.
:
187
m r-7-I
f-3
Fig. 56
The component in question is a mild-steel, shouldered
bushing with chamfered
edges and having a through
b&p
of g in. cIiDmPter
to which the part
-.."a.A.,-w_ J the dimensions
has to be machined are shown in the drawing.
A length of I in. diameter mild-steel rod, as shown in
,,Fig. 563, is used, and, t? suit our present purpose, we will
” ,,take::it ‘that a bpre of $me::$,,i&
lys already ,been ,dx?lle$
‘,
:,
~lycju~h it as, @ill be ,dc;c~ibed~ljter,-in ,th~s chapter. ‘,
:,~,,,:
188
The rod can be mounted in the self-centring chuck as
it does not matter if it runs slightly out of truth, for there
is pl.enty of metal to spare ; but if the four-jaw chuck is
used, the work can, of course, be adjusted to run truly,
and, in addition, it will overhang less and so will receive
more rigid support from the mandrel bearings.
Before describing
the actual
turning oper,ations, it
should be emphasised that, as mistakes resulting in spoilt
work are easily made when machining, it is advisable to
guard against this by adopting a methodical
way of
working which keeps a continuous check on the progress
of the work. To save the machine drawings from damage
Fig. 57
and to ‘make clear exactly what is required, make a simplified dimensioned
sketch of the actual part to be
machined.
As illustrated in Fig. 57, mark on the left of the sketch
the length of any turned portions, and on the right note
the diameters to be turned. To avoid errors when feeding
in the tool, start with the, cross-slide index set to its zero
position with the tool’ touching, the, work. If the,diameter
of the material is I in. and it has to be reducedto
3 in.,
189
then the final reading of the index will be approximately
60.
Measure the diameter of the work with the micrometer
after taking a cut, and note on a piece of paper both the
work diameter and the index setting.
A further measurement should be made before taking the finishing cut to
ascertain the exact setting of the cross-slide required.
If
the diameter of the work and the cross-slide settings
correspond throughout the turning operation, there should
be little chance of making a machining error.
To b&n the machining operation, add a few drops of
machine oil to the mandrel lubricators, and then clamp
a right-hand knife tool in the tool post with its cutting
edge set to the exact centre height of the lathe ; this is
best done with the aid of a specially made height gauge
standing on either the saddle or the bed of the lathe, or
the ordinary surface gauge may be used for this purpose.
As the material to be machined’is I in. in diameter, the
low direct-speed of the lathe should be used to give between
200
and 300 r.p.m., in accordance with the calculations
previously cited.
The next step is to face the end of the work with the
knife tool as shown in Fig. 56c ; the tool is fed to the work
by means of’ the top slide after the leadscrew index has
If the tool is set correctly
been set to the zero position.
to the centre height, no unsightly central pip will be
formed when a solid bar is faced.
To reduce the diameter of the bar from I in. to Q in.,
the lathe is stopped and the cutting point of the knife tool
is brought gently into contact with the work on its outer
diameter ; the cross-slide index is then set to zero, and
when the tool has been moved clear of the work to the
right by means of the leadscrew feed; a cut of some 30
thousandths, or so, is put on with the cross-slide feed.
When turning short lengths of material, hand-feed for the
saddle can quite well be used, but the automatic feed
will, as has been pointed out, give better results and should
be used in this instance.
,,”
It will be clear that, where the pitch of the leadscrew
is Q in., to cover the I in. length to be turned, the leadscrew
index will have to revolve exactly eight times, starting
from its zero position as previously set when facing the
end of the work.
In addition, the tool will have to be fed inwards by the
cross-slide for approximately
125 thousandths
to reduce
the diameter of the bar to the finished size.
Start the lathe, and when the leadscrew index has
turned a few thousandths of an inch short of eight full
turns, throw out the leadscrew feed. The full number of
turns made by the leadscrew can be determined with the
aid of a rule or from a chalk mark made on the work.
This operation is repeated until the work has been
turned to the correct diameter as determined with either
the micrometer
or the outside callipers ; but for the
finishing cut a feed of a few thousandths only should be
allowed in order to produce a good finish on the work.
To turn the reduced portion to an exact length of I in.,
the final few thousandths of an inch of traverse are made
by turning the Ieadscrew by hand until its index reaches
the zero position
Next, the diameter of the head of the bushing is reduced
in the same way to I 5116 in. in accordance
with the
dimensions given in Fig. 56~, and the edges are chamfered
as shown in Fig. 56~, but the lathe may have to be run at
a slower speed for this latter operation if there is any
tendency to chatter.
The form of chamfering tool used
is illustrated in Fig. 49~.
Boring.
This completes the turning of the outside
diameters, and the forming of the bore to size is now undertaken with a small boring tool, as represented in Fig. 5%.
‘f’hc: form of boring tool used for this purpose is illustrated
in Fig. 58, and the position of the cutting edge when at
work is aiso shown in Fig. 58~.
As the diameter of the work being turned is now less
than half of what it was when the machining was begun?
the speed of the lat!re can saft.ly be doubled, but only light
191
cuts should be taken to avoid over-stressing the rather
The automatic feed for the saddle
slender boring tool.
is used, an.d the depth of entry of the boring tool must be
controlled by reference to the leadscrew ‘index, in order
BORlbiG
-7
TOOL
relief
,seen from
&Q&
w
ciedrdnce
Fig. 58
to prevent the tip of the tool from being forced against the
shoulder formed at the end of the bored hole. Should the
bore pass right through the work, a packing of ,rag or \,
cotton wool should be inserted, to’ prevent’ the cuttings \
\
from reaching the working’parts in the interior.ef the chuck.
\,
\
192
This
The next operation is to part-off the component.
is done, as illustrated in Fig. 56~, with a nzu-row parting
tool of the form shown in Fig. 4go. Until some -experience
has been gained, it is advisable to use the back gear of
the lathe fur this operation, and great care should be taken
to maintain an even rate of feed so that a coiled shaving is
produced which readily clears itself from the groove cut
in the work. Oil should be applied continuously with a
brush to promote free cuttin~g, but should the tool dig
in’ and become jammed in the work, it is advisable to
sl,acken the clamping screws and remove it carefully,
When
otherwise its tip will almost certainly be damaged.
using the parting tool it is essential that the cross-slide
should be properly adjusted to remove slackness and undue
backlash in the feed mechanism.
The final operation, after reversing the work in the
chuck, is to face its end as shown in Fig. 560, and then to,/
chamfer the rim in accordance with Fig. 56~.
Use of the Faceplate. Where the work is too irregular
in shape or too bulky to be held in the chuck, it can usually
be clamped to the’:, faceplate for machining,
but if the
turning is to be accukately carried out, the faceplate must,
of course, run quite truly. The true running of the faceplate can be checked with the test indicator, mounted in
the lathe toolpost and with its contact point brought to
bear on the surface of the plate while slowly turned by
hand.
Untrue running may result from the presence of dirt
or -chips on the mating surfaces of the mandrel nose or
faceplate, and may not be due to inaccurate machining.
Fig. 5g shows an engine casting attached to the faceplate
by means of clamping pieces and bolts.
The rear face
of the casting has been previously turned so that it beds
evenly on the faceplate and thus ensures that, when the
crankshaft bearing is bored, as illustrated in the drawing,
it will lie truly at right angles to the surface in contact
with the faceplate.
Should the form of the work not permit it to be mounted
193
/
::, ,~i
::
i,:
,,
\
195
in this way, or if, as shown in Fig. 60, the bore has to be
machined truly parallel with the base surface, then the
work can be clamped to an angle-plate which is in turn
secured to the faceplate.
This method of mounting allows the position of the
work to be readily adjusted when centring the bore.
It will be observed that a counterweight
has been
attached to the faceplate.
This should always be done if
the work is out of balance, otherwise inaccurate machining
may result. The position and size of the weight are adjusted until the lathe mandrel, when running free and turned
by hand, has no tendency to stop in any one position.
When mounting work on the faceplate in the ways
described, a firmer hold will be obtained if a single sheet
of paper is placed between the opposed flat clamping
surfaces.
Turning Work Between Centres.
Components
that
project for some distance from the chuck in which they are
mounted often require additional support from the tail,,,, stock centre to provide the rigidity necessary for machining.
;,”
To allow of this, the faced end of the work is drilled
:‘,, with a centre drill of the type illustrated in Fig. 17, in
Chapter One.
The form of .the hole so made is shown in section in
Fig. VIA, and Fig. 61~ represents the appearance when the
tailstock centre is engaged.
It will be seen that the centre
itself remains clear of the bottom of the hole, and a space
is left which forms an oil reservoir for lubricating the working surfaces.
Should, however, a defective centre drill
be employed, the centre may bottom in the hole, as shown
in Fig. 6xc, and no proper guidance will be provided.
Shafts, such as crankshafts and machine spindles, are
turned between the two lathe centres, and this method of
mounting the work has the advantages that no bending
strain is imposed on the shaft, and should remachining be
required at any, time, the shaft can be mounted to run
truly on the original centre holes.
When centre-drilling
the ends~ of a long shaft which
196
will not pass through the bore in the lathe mandrel, one
end is set to run truly in the four-jaw chuck and the other
is supported in a fixed steady secured to the lathe bed, as
‘illustrated in Fig. 62.
The end of the shaft so mounted is faced and afterwards
drilled with a centre drill ; the shaft is then reversed in
the chuck and the other end is machined in a similar
0
Fig. 61
manner.
This method of mounting and driving the work
can also be employed when turning the taper bore in the
”
end of a machine spindle or mandrel.
To provide for driving ,the shaft when it is mounted
”
bet7Neen the lathe centres, as illustrated in Fig. 65 a lathe
carrier ,is attached to its end, as shown in Fig. 69,
__ : in
addition, to,, ensure, that ,the carrier does not slip, particu.
,‘, “,‘,
larly when cutting a,: screw ~‘&ead’ on the shaft, a smaJl
flat ?;a)’ k, filed on,‘~ui$inished~ork’ to give a,,,,bearing for ’ ‘, ‘,, i
Pig. 63
the point of the clamp screw.
Where finished work is
held in this way, a piece of sheet-copper should be wrapped
round the shaft to prevent it being damaged.
When the work has been mounted between the lathe
centres, the tail of the carrier is driven by a dog or bolt
attached to the driver-plate screwed on to the mandrel
nose of the lathe.
To prevent the dog from knocking against the carrier
during the turning operation, the parts should be lightly
bound together with a piece of wire.
If the end of a shaft where it is engaged with the tailstock centre has to be turned to a small diameter, it may
be found that the ordinary form of back centre will not
allow the point of the tool to be 6ed far enough inwards ;
Fig. 64
,,,
,,,
19:’
to overcome this difficulty a special cut-away or halfcentre is used with the $at surface at the tip turned towards
A centre of this type is shown in Fig:, 6.4.
the operator.
The back centre should bc kept clean and weil-iubricated, and it is engagcad with the work just sufIicicntIy
firmly to ensure that all side-play is taken up ; during
the subsequent
turning operations the tailstock centre
should be reset in the work from time to time, as the heat
---
\\ UT---r-v
w
LJ
eqendered
by the m;u:hining CXIIWS tl~r work IO cxp~ntl
‘In length and tighten on t,hc centre.
The actuzd machining of the: shaft is carried out as in
the previous example, but wl~n a long or slender shaft is
being turned, it may be found ;Ilccc*ssary t,o give it support
against the thrust of the tool by using a travelling steady,
as illustrated in Fig. 65.
This device is attached to the Iatho s;tddIe:, and its two
contact pads support the work as ~hey fi)llow in t!lc wake
of the, tool.
,,,
,‘:
200
Fig. 66
It is necessary, of course, to readjust the pads after
each passage of the tool along the work.
Boring Work 02 the Saddle. When a casting is too
large to be held in a chuck or mounted on the facep!ate,
it can sometimes be bored and machined if clamped to
the lathe saddle, as illustrated in Fig. 66.
The boring
operation is then carried out by means of a boring bar
mounted between the lathe centres.
This bar is fitted with a cutter which can be adjusted,
as shown in Fig. 67, to the radius required to machine
the bore to size.
An alternative method of driving the bar is to grip it
close to its end in the four-jaw chuck and to support the
other end with the tailstock centre. This allows the radius
of the cutter point to be accurately set by adjusting the
This fine adjustchuck with the aid of the test indicator.
ment is made, when the bore is nearing its finished size,
by mounting the indicator on the lathe and resetting the
bar in the chuck with the point of the cutter in contact with
the button of the indicator.
If the lathe is turned slowly
backwards by hand, a reading of the indicator can be
,,
201
taken both before and during the setting operation to
enable an exact amount of feed to be given.
Drilling from the Tailstock. When a drilling machine
is not available, the lathe may be used as a substitute by
mounting a drill in the mandrel chuck and supporting
A
the work against a drilling pad fitted to the tailstock.
drilling fitment of this type is illustrated in Fig. 38 in
Chapter Three, which shows a tapered adapter fitting
into the tailstock taper and having a paraliel portion at
its front end to carry either a plain or a V-slotted pad to
accommodate round work.
On the whole, this is not a very satisfactory method of
drilling, for it is difficult in this case to keep the work in
position and to locate holes accurately.
If, however, the work-is mounted in the mandrel chuck
and the drill is fed from the tailstock, very accurate work
can be done if reasonable care is taken.
For this operation the drill is held in a drill chuck
mounted in the tailstock taper by means of a tapered
arbor.
As so many less experienced workers complain
that they are unable to drill a true axial hole in this
manner, it may be worth while to describe the operation
in detail.
Fig. 67
20%
In the first place, the tailstock must be truly aligned
with the headstock, and properly sharpened drills are
essential for accurate work. Let us take as an example the
drilling of an axial hole & in. in diameter in a piece of
round material mounted in the lathe chuck.
The end
surface of the work must first be turned flat and without a
central pip. A small standard centre drill with a body
.Ain. in diameter and with a 3164 in. drilling point is secured
in the drill chuck fitted to the tailstock taper. With the
latlte set to run at high speed, the drill is fed into the work
until the parallel body portion has entered for at least
Q in. An 4 in. twi,st drill is then secured in the drill chuck
and is entered for the full depth of the hole required.
The
guidance affcrded by the drilled centre will ensure that
the & in. drill starts truly, and if it is fed in carefully a
true hole should result.
The mouth of the hole is now enlarged with a larger
centre drill to form a guide centre for the & in. drill which
followsand enlarges the hole to its finished size.
Should a hole smaller than & in. have to be drilled, the
parallel, drilling portion of a centre drill can be used to
form the guide hole for the pilot drill, and the hole formed
by this drill is then enlarged to the full size to complete
the operation.
Depth Drilling. Where the tai!stock barrel is graduated
as illustrated in Fig. 68~, the depth of entry of the drill
PENCIL
Fig. G8
MARK
:::i,
:‘:,,
can, of course, be read directly, but when the barrel is
left plain, a penci,l n&-k is made, as in Fig. 68B, to denote
the start of the drill i:$ the work, and its progress is determined by measuring %th a rule the distance between this
mark and, the edge of the tailstock casting, as represented
in Fig. 6%.
The ’ D’ Bit. A ready and accurate method of drilling
deep holes from the tailstock is to use a D bit of the form
shown in Fig. 69.
This tool is easily made from a length of silver-steel,
filed to the shape shown in the drawings, and then hardened
and tempered in the manner described in the instructions
for making a countersink in Chapter Six. It will be seen
that both clearance and relief angles are formed at the
cutting point of the tool, and the flat stirface behind the
cutting edge lies a little above the diameter in order to
maintain guidance.
It is essential when using these cutters to start them in
a truly centred hole of a diameter exactly equal to that
of the tool ; to give adequate guidance at the start, this
hole must be formed to a depth equal to the diameter of
the cutter.
Dieing and Tapping in the Lathe. If reasonable care
is taken, parts, held in the lathe chuck and turned or bored
to size, can ,be’~threaded sufficiently accurately for most
purposes by means of ,a,d,ie,or ttip ,guided by the tailstock.
,,,,
,,,,
,,,,,,,,,:
,~:i,‘~
,,
204
*~,,
,,:,
f<Z!,,,,~
,\$y:‘:
,,,
Eig. 6g
$?;,:)<t;
~
Lg&
m:_,
,,,,~,
For cutting external threads, a dieholder, such as that
made by Messrs. Myford, and illustrated in Fig. 70, is
,,,,
,‘,,,
~,‘,‘~,,
mounted by its tapered shank in the tailstock barrel.
!,,,,
The die, which is secured in the head of,the die holder
,,_: ‘,
by the adjusting screws, is then fed forward by means of
the tailstock screw-feed to engage the work as it is slowly
,,
rotated.
,,:‘,
The lathe, mandrel is rotated either by pulling on the
belt or, preferably, by means of a special handle secured
to the rear end of the mandrel itself. While the first few
threads are being cut;, some pressure should .be exerted
” by ,the ,tailstock,,to overcome’, thecutting
~&&sure ‘&d,Is.o
” p,revent ‘:these threacls’,being,‘thinned’,,; ,“but, ,&:sooti ‘as the
~’
‘, ,’
,,
,,,,
~,~~,~ ,~:;
,‘,‘,:,:‘;‘,“,‘,
,, ,,: : :,,~~,,,:
‘:,~,,:,~:
,’ :,, ,,,+‘,~
,,,,:: :!,,,~,;;,
,,,,,:,:;,,~;
::,,,;:,,,;,,:
;:: :’;~,
,,,,
:;,,:::
~, ,‘~
,:i~:,;,
205
die has obtained a fair hold it will continue to cut as it
feeds itself along the work.
During the threading operation, the handle attached
to the die-head can either be controlled by the hand, or
allowed to engage some part of the lathe, in order to
prevent the die turning with the work.
When a large thread is being cut in this way, once the
die has obtained a good hold the work can be removed
from the lathe and the threading operation completed at
the bench ; this safeguards the chuck, which might otherwise be strained in an attempt to prevent the work from
slipping in its jaws.
Tapping a hole centrally drilled in the work mounted
in the chuck is carried out by supporting the shank of the
tap in the tailstock drill chuck.
The jaws are closed
sufficiently to provide guidance for the taF without preventing it from turning freely.
A small lathe carrier is secured to the tap to afford the
necessary turning leverage, and, with the lathe mandrel
locked, the tap is worked to and fro until the threading
is completed.
,,
A,6
Here, again, if much resistance is encountered when
cutting the thread, the work should be removed from the
lathe and the operation completed at the bench.
Screw Cutting.
Clearly,
if a tool with a V-shaped
point is mounted in the lathe tool post, and a cut is taken
along a piece of work with a rather coarse automatic feed,
a spiral groove will be formed which is essentially a screw
thread . Reference to the makers’ screw-cutting chart will
show the arrangement of the change-wheels necessary for
cutting any particular
thread ; but the operation will
be simplified if the beginner is content, for a time at least,
to cut only thread pitches that are a multiple of the leadscrew thread of 8 t.p.i., that is to say 16, 24 and 32 threads
per in. for example.
The ,corresponding wheel trains are simple, too, and
merely call for a reduction of 2 to I, 3 to I, and 4 to I
respectively.
There is also no dieculty
in engaging the leadscrew
nut at the right moment, as any position relative to the
work will be correct ; but when odd pitches are cut, if
the leadscrew nut is not engaged correctly a second thread
will be cut on top of the previous thread.
It is now usual, however, for manufacturers
to fit a
thread indicator to enable the operator to engage the
leadscrew nut at the proper time.
To put the matter briefly, if a V-pointed tool, Farmed
to the correct angle, is mounted at centre height in the
lathe-tool post, and is used to make a series of cuts with a
feed equal to a multiple of the leadscrew pitch, then a
satisfactory thread can be readily formed on either the
external or theninternal surface of the work.
The commdnly used Whitworth form of thread has
an included angle of 55 deg., and thread cutting tools
should have their points ground to this angle, as shown in
Fig. 490, but when sharpening these tools additional
clearance must be given to allow for, the spiral course of
the thread.
It is important,to secure the tool exactly at centre height,
I-:’‘:’
207
otherwise it will n’ot cut the thread to the correct form.
An initial cut of 5 thousandths of an inch may be taken,
but this must be reduced as the work proceeds or the
slender tip of the tool may be damaged.
Until experience is gained, the slow speed of the back
gear should be used to allow time for the tool to be withdrawn at the end of the cut ; if possible, a groove should
be turned in the work at this point to safeguard the tool.
Fig. 71
When the end of the thread is reached, the tool is
withdrawn, the leadscrew nut is disengaged, and the saddle
is returned to the starting point. As the thread being cut
is a multiple of the leadscrew thread, th,e clasp nut can
be engaged at any point when taking the next cut. This
procedure is continued until the thread has been formed
to the full standard depth.
Internal threads are cut in the same ivay, but additional
care is required to ensure that the tool is not damaged
when it reaches the end of the thread, for in this case it
will be out of sight an d its depth of entry must be controlled
by reference to the leadscrew index.
The usual form of
tool for cutting internal threads is illustrated in Fig. 71.
Only a brief outline of screw-cutting procedure has been
given, and the question of cutting threads of odd pitch,
and the method of screw-cutting with the tool-slide set
at an angle have necessarily been omitted, but this subject
is fully dealt with in any practical text-book on lathe work.
Hand Turning Tools. In the days when the small
lathe was not often fitted with a slide rest, hand-turning
tools were largely used by the amateur and also by the
professional instrument maker.
208
In the hands of the skilled craftsman the graver, shown
in Fig. 72~, is capable of doing accurate turning over a
wide range of work, such as both parallel and taper turning,
and also forming parts with curved surfaces.
The amateur,
however, uses the graver mostly for
rounding the edges of work where he finds the slide-rest
of little help.
A graver can be made from a discarded square file by
grinding the tip to the lozenge shape shown in the drawings;
the teeth on the blade of the file should be ground smooth
to save the hands from damage.
To form a fine cutting
edge, the sharpening must be completed by stoning the
diamond-shaped area at the tip with the aid of a stoning
,i!g which maintains the tool in correct alignment with
the surface of the o&tone ; this is fully described in
Shpmin,~ Small Tools, published by Argus Books Ltd.
209
1
@
Fig. 73
The blade of the tool should not be less than 4 in. in
length to provide a grip for the left hand, and a wooden
handle is fitted to afford the right hand a secure grip when
‘):,: steadying the tool at its further end.
1 The method of using the graver is illustrated in Fig. 73,
and1 it is important that the tool-rest should be set as
‘, closely as possible to the work to prevent the point of the
tool. from being drawn downwards and caught in the gap
:betlNeen the work and the rest.
When the tool is presented to the work as shown in
Fig. 73~, it has no top or side rake and will then turn brass
to a good finish, but an even better finish can usually be
obtained by rotating the tool until it has a negative rake
,.;n relation to the work surface.
The arrows in’the figureindicate
the direction in which
210
the handle is moved when forming a radius on the edge
of the work.
When turning steel, the graver is applied to the work,
as shown in Fig. 73n, and the rake angles then cause a
slicing cut to be taken as the tool is turned on its long
axis to form a radius on the work.
As only light cuts are, as a rule, taken with the graver,
the turning speed can be high, but if there is any tendency
to chatter, the speed should be reduced.
With practice, small parts can be turned parallel by
hand-turning with the gra*Jer ; the handle of the tool is
steadied with the right hand, and the left is used to pull
the graver along the tool-rest for a short distance towards
the left ; the grip of the left han.d is then shifted and a
further cut is taken.
Finally, the turned sections are
merged to form a continuous parallel surface.
If preferred, hand tools of the ordinary !&the tool form
can be used instead of the graver for finishing curved surfaces ; these tools are particularly useful for turning brass
and aluminium.
The squ.are-ended tool, shown in Fig. 72~, can be used
to form an external radius by swinging the handle horizontally while the end of the tool is allowed to pivot on
the hand rest ; and, as in the previous case, if the handle
is raised to give a begative rake to the tool, a very fine
finish can be imparted to the work.
The round-ended tool, depicted in Fig. 72~4 is used in the
same way for forming hollow-curved surfaces.
CHAPTER
SIX
,,,‘,,,
,,,
212
To do this, a short length of round-steel of a diameter
greater than x3/16 in. is mounted in the self-centring
chuck, and its end is turned down to form a firm press-fit
in the die housing of the holder.
The die holder is pressed into place on the spigot and,
to give additional securiry, the grub screws used to hold
the die are screwed firmly home.
Reference to the working drawing in Fig. 76 will show
that the register on the adapter where it fits into the holder
is I I /I 6 in. in diameter ; the corresponding bore in the
STANDAM
PATTERN
DIE HOLDER
Fig- 74
holder is, therefore, turned to this dimension and the face
of the holder is machined flat with a knife tool.
The adapter itself is now taken in hand, and for its
construction a piece 14 in. in length is cut off f?om a steel
bar I in. wide and 4 in. thick.
Prior to machining, the work is marked-out in accordance with the working drawing and as shown in Fig. 77~.
The cross-centre lines are scribed with the jenny callipers,
and from the point of intersection the screw hole centres
are marked-out ,+h, the ,,dividers, set to 71x6 in. These
,centres are ‘,then drilled Iwith, a’ ‘NO. 34 ‘drill to’, provide
cleararrce’ holes ,for ,the ‘6, BA. fixing screws. The centre
,’
”
,’
,,,
,‘,’
I
I
OF THE
‘AND THIS FACE
WITH THE.BORE
MAY
DIE-SEATING
BE OUT-OF-SQUARE
*.
Fig. 75
of the work is drilled with a centre drill to form a bearing
:, for the centrefinder when setting
the part in the chuck.
The appearance of the work when mounted in the lathe
is then as illustrated in Fig. 77A.
It should be noted that packing
pieces must be placed behind the
work to bring it forward in the
chuck jaws so as to allow 8 in.
to project for forming the collet
boss shown in Fig. 77~. The next
step is to drill and bore the part
to 15/32 in., as in Fig. 77~. The
I
Id
collet boss is then turned to Q in.
diameter for’ a length of fs in.,
as shown in Fig. 770.
The work is now reversed in
the chuck and held by the collet
boss. The machining in the lathe
is, completed
by’, turning ‘the
register ,to,,a ,depth of & in. and
Fig. 76
214
MOUNT
CHUCU
_---
BAR IN &JAW
_~l_L-I
BORE
15!32*DtA
@
TURN 13ilS*DIA
8055
t
I
-,I -__lo
--.-/* D
I
0
0
Cl
c
,--2
AEVERSiT A?iD CENTRE
F3R TUtiNlNC
11116’01A
REGISTER.
OPEN 15132
BORE TO 1/2’DIA
0
0
0
l/2’ DIA
then finishing the bore to exactly -A in., as depicted in
Fig. 77~.
‘i’he next operation is shown in Figs. 77E and F and consists
in cutting the chip clearancc~ slots with the: hacksaw and
file.
After this, as seen in Fig. 77~5, the screw holes are countersunk, and ,the adapter is:filed, tqits finished, shape. Finally,;,
the hole for ,the ,6 P.A. collet ,‘clamp, s&ci.b ,is ,drilled and
,$apped, ‘and; with the: adapti+ clamped in place ‘in’ thhe
MAKE TWO DIAGONAL
HACKSAff CUTS
FILE TG MPYE
CLEARANCE
SLOT
DRILL At*:3 COUNTER
S,NK FI:$lNC SCREW
tiOLES.
~EHAPE FIXING
FLANGE i&S REcVJlRED
--~+
_._-
_-._
-_.-.__,_-.--_-
Fig
-.-.
I..
77
,;;;,;:;
:;,-,;,:
,,,,,;, “:
:,,,
,,,,
:,,“,’ ,,‘:,die holder, the holes for the t’?B.A. fising screws are drilled
and tapped.
Collets.
The standard form of collet shown in Fig. 78,
:,
can be machined from a length of g in. diameter mild- or
silver-steel mounted in the lathe chuck.
The spigot is
turned to $ in. diameter to fit the adapter, and a groove
,,
should be cut with a V-pointed tool to receive the point’
,of the fixing,screw.
‘, The guide, hole is +illed centrally in’ accordance with
,::
:
‘:,,
,’
,,,,,
: ,, ,,’
,‘,,
,,
,,
,,,
,,,
,~ ,,,,,
“,
,‘,,
215
the method described for drilling from the lathe tailstock
and, finally, the collet is parted off. If the collet is to have
much use it should be case-hardened or hardened in the
manner already described, but, as a rule, this will be found
unnecessary in the small workshop especially if silver-steel
is used for the construction.
,,
,,~
A Colleted Die Holder.
This
die holder, which is
illustrated in Fig. 79, has a central body piece machined
from the solid and carrying two handles.
Although the holder is primarily intended for hand
threading, it can be used as a tailstock die holder when
one handle is unscrewed.
For the latter purpose, an
arbor is used with a tapered shank to fit the tailstock
taper, and a parallel portion on which the die-holder collet
slides to guide the die.
The holder is machined to take the standard form of
collet used in the previous example.
Three screws are fitted for holding the die ,when resting
against the shoulder of the die housing shown in the drawing, and the flared slot provided for chip clearance will
be seen towards the lower part of the front face of the
device.
The working drawings given in Fig. 80 will make clear
the actual construction of the holder, and it will be apparent
that it can be made from a f in. length of I in. sq. mild*_
steel bar.
,, One end of the bar is filed ~flat and the centre is marked-
,~ ,,,,,
“,
,‘,,
215
the method described for drilling from the lathe tailstock
and, finally, the collet is parted off. If the collet is to have
much use it should be case-hardened or hardened in the
manner already described, but, as a rule, this will be found
unnecessary in the small workshop especially if silver-steel
is used for the construction.
,,
,,~
A Colleted Die Holder.
This
die holder, which is
illustrated in Fig. 79, has a central body piece machined
from the solid and carrying two handles.
Although the holder is primarily intended for hand
threading, it can be used as a tailstock die holder when
one handle is unscrewed.
For the latter purpose, an
arbor is used with a tapered shank to fit the tailstock
taper, and a parallel portion on which the die-holder collet
slides to guide the die.
The holder is machined to take the standard form of
collet used in the previous example.
Three screws are fitted for holding the die ,when resting
against the shoulder of the die housing shown in the drawing, and the flared slot provided for chip clearance will
be seen towards the lower part of the front face of the
device.
The working drawings given in Fig. 80 will make clear
the actual construction of the holder, and it will be apparent
that it can be made from a f in. length of I in. sq. mild*_
steel bar.
,, One em-l of the bar is filed ~flat and the centre is marked-
218
r-----7
Fig. 80
of the fixing screws ; but if three screws are fitted, as
shown in the drawings, these should be suitable for holding
most dies.
The handles are made from lengths of fi in. steel rod,
reduced at the ends to $ in. for threading and screwing
into the body.
If the die holder is to be used ,for threading from the
lathe tailstock, it is advisable to drill a cross-hole near the
outer end of one handle to take a tommy bar, so that the
arm can be readily removed when required.
AS
A Tapping
Handle for the Drilling Machine.
described in Chapter One, the drilling machine can be
used for tapping holes when a tap is mounted in the chuck
and the spindle is turned by a handlesecured
to its upper
end.
An easily made handle for this purpose is shown in
Fig. 81, and the full \\orking drawings are reproduced in
Fig. 82.
The collar (I) that carries the handle bar (3j is clamped
to the drilling machine spindle by the screw (6) whose
point, engages in the spindle keyway. To alter the leverage
obtained, the screws (5) holding the clamp plate (2) are
slackened, and the handle bar can then he moved to any
position required.
The Handle Bar (3:) is made from a Length of 4 in. b>.
A i in. diameter hole to receive the shank
4 in. mild-steel;
of the handle is drilled i in. from one end, and So& this
and the opposite end oi’ the bar are rounded off by filing
L’he sidmesand edges of the bar
as shown in the drawing.
are then draw-filed with a fin? file to compiete the work
on this part.
Fig. 81
N
I::
221
The Handle (4) of the rounded formshown in the drawing is turned to shape with hand tools from a piece of
4 in. diameter round bar ; this is followed by using a
fine file and emery cloth on the rotating work until a good,
smooth finish has been obtained.
To avoid using hand tools, the handle can, if preferred,
be made in the form of a straight taper as in the drawing.
This taper is machined by setting the lathe top-slide to
an angle of some 2 deg., and the top of the handle is then
rounded or chamfered to give a good appearance.
After the handle has been turned to shape it is parted
off, but care must be taken to ensure that both the upper
end of the handle and the collar at its base are of equal
diameter, to enable it to be held securely in the chuck for
turning the spigot.
The handle is gripped in that self-centring chuck over its
two 4 in. diameters, but a piece of thin card or sheetcopper should be interposed to prevent damage to the
work surface.
The spigot is turned to a good press-nt in the handle
bar, that is to say it should be made about a thousandth
of an inch larger in diameter than the hole.
The polishing operation is best carried out with the
spigot of the handle secured in the chuck of the drilling
machine, for a high QWA
SYUW-is
_ then available,and, in addition,
there is no danger of the abrasive dust formed causing
damage to the machine, as may happen when the lathe is
used for this purpose and the slides are not well-protected
by temporary coverings.
After it has been polished, the handle is pressed into the
bar with the aid of the vice, and the part projecting is
lightly riveted over with a hammer to make the joint
secure.
The Collar (I) is turned from a short length of I in.
diameter round mild-steel bar held in the self-centring
chuck. The central hole is drilled and finally bored to fit
the drill spindle, and after the lower part has been reduced to
I 5/r 6 in. in diameter, the collar,is parted off Hin. in length.
2:22
The work is then reversed in the chuck to face the upper
surface of the collar. The dimensions of the slot to receive
the bar are marked-out by clamping the work in a V
block standing on the surface plate, and scribing parallel
lines with the surface gauge from the upper and lower
edges of the bore.
The depth of the slot is marked-out with the surface
gauge while the collar is stan,ding on end on the surface
plate.
Cuts are then made with a hacksaw inside the scribed
lines and to a depth just short of the dimension lines
scribed on the outer diameter.
The slot is filed to shape
to fit the bar, but the latter must stand slightly proud so
that it receives the pressure of the clamping plate.
The Clamping Plate (2)
is best made by facing the
rnd of a short length of I in. diameter round-bar held in
lhc- self-centring chuck and then parting off a disc & in.
ir! thickness.
The central pip left on the work can he
removed with the aid of a scraper.
The position of the screw holes is determined by scribing
a line through the centre of the plate and marking-out
the two drilling centres with the jenny callipers set to
5/32
in. ; the two screw holes are drilled with a No. 27
drill.
The collar with the claiiiping piate in position i,s clamped
in the upright position in the machine vice, and the No. 27
drill is entered in the previously drilled holes and fed
into the collar fcr & in. This drill is followed by a No.
32 drill, and the holes so formed are tapped No. 4 B.A.
in the drilling machine without disturbing the setting of
the parts in the vice.
It no-w remains to fit the two 4 B.A. hexagon-headed
screws for the clamping plate and the 2 B.A. clamp screw
to the collar.
After the position of the clamp screw has been markedout, the collar is secured in the machine vice and a No. 2
B.A. tapping size hole is drilled on the diameter with a
No. 22 drill and then tapped.
i
223
The three screws required are best made from hexagon
rod, but if this is not available, round steel-rod may be
used. The shanks of the screws are turned to size in the
lathe and then threaded with the aid of the tailstock die
holder. The hexagon heads are formed, when necessary,
by fi!ing the round rod to shape, using a standard nut
screwed on the screw blank to act as a filing guide.
It
is advisable to form the same size of hexagon on all the
screws so that a single spanner wil! serve for ail adjustments.
When making the 2 B.A. clamp screw, its tip should
be reduced in diameter to .allow it to enter the spindle
keyway, and. a brass disc should be used to take the clamping pressure to save the keyway from damage.
As an alternative, the screws can be turned from square
rod held in the four-jaw chuck ; this will save the filing
work necessary in the previous case to form the heads to
shape.
To add to the appearance of the work, the screws can
be blued by heating them in the flame of a spirit lamp and
plunging them into oil as soon as the desired colour is
reached.
As has been pointed nut
Making a Countersink.
commercial
countersinks
with several cutting lips are
liable to chatter when used in small drilling machines,
and, to overcome this, the single-lip form of cutter shou!d
be adopted.
A cutter of this pattern is illustrated in Fig. 83, where
it will be seen that the point is formed to include an ang1.e
of go deg., and the flat cutting face lies a little above the
This construction gives a single cutting edge
diameter.
whilst the other lip acts as a guide or steady to prevent
chatter.
To make the cutter, a short length of 4 in. diameter
round silver-steel is set to run truly in the four-jaw chuck,
and the shank is turned to a diameter of & in. to enable
it to F:e held in the chuck of the small driliing machine.
‘Th;: work is ‘then reversed ,in the chuck and, after it
: has been set truly, the ti@is turned to an angle of,go deg.
224
by setting the lathe top slide to 45 deg. The knife tool
used for this operation should be set to the exact centre
height ; this can be checked, when facing the end of the
work, by adjusting the tool so that no central pip is formed.
The cutter is then removed from the lathe and secured
in the vice for filing the flat face ori the tip as shown in the
Fig. 83
drawing ; this face must be formed slightly above the
diameter, and a measurement taken with the micrometer
will help to determine this exactly.
The next step is to harden Andytemper the tool ; it is,
therefore, heated to a bright cherry-red and plunged into
cold water ; test the steel with a file, and, if the file slides
over the surface without cutting the metal, the cutter is
fully hardened.
Clean the work with a piece of fine, worn emery cloth,
and heat the shank carefully ,in a small flame until the tip’
assumes a straw colour, then plunge ,&he cutter into cold
water and the tempering is completed, leaving the tool
tough ,and not brittle as in the fully Hardened state.
Finally, the flat face of the cutter should be honed on
an oilstone to finish the sharpening, of the cutting edge,
but in both this and in any subsequent sharpening operations care must be taken to maintain the cutting edge
above ‘the diameter, otherwise~, the non-chattering
pre
” perties of the tool will: be lost.
,,:IYe
225
Counterbores and Pin Drills.
The purpose for which
these tools are used has been described in Chapter One,
and there are two forms in common use ; the two-lipped
flat cutter with a solid central guide pin, as shown in Fig.
84, and the cutter with two or more cutting lips and a
detachable guide-pin as illustrated in Fig. 85. The latter
is usually referred to as a pin drill, and it has the advantage
that guide pins of various sizes can be used in a single
cutter.
To make the flat form of cutter, a length of silver-steel
is centred in the four-jaw chuck and the shank‘is turned to
the required diameter and length.
The work is then
reversed in the chuck and, after it has been faced and a
light cut taken over the body, the central pin is formed
with a knife tool leaving a square shoulder.
,‘~,~
;:,,
The cutter is next gripped in the vice and the flat faces
::,1
:,,,,,
are formed by filing, but care must be taken not to damage
c>,,:, the central pin. The two lips are then shaped with a fine
(:~~:, file to form the cutting edges as shown in the drawing.
i[;;,!,‘~
$;;;,‘,;,
>
,,
fj;$;’
,,,,,,
,‘,
-&
1
Fig. 84
After the cutter has been hardened and tempered, as
described in the case of the countersink, the cutting edges
are carefulIy honed with an oilstone slip to impart the
final sharpness.
The pin drill shown in ,Fig. 85 is also made of silver-steel,
226
and it &ill be an advantage to make a set of these useful
tools to cover the range of work normally undertaken.
In the smaller sizes 3132 in.. diameter guide pins can
be used, but for sizes above and including & in. a Q in.
diameter pin will be found more serviceable.
When making large cutters, a shank of reduced diameter,
as in the previous examples, may be required to fit the
chuck of the drilling machine, but smaller cutters can be
made parallel throughout,
as shown in the drawing in
Fig. 85A.
A length of silver-steel is centred in the four:jaw chuck
and its end is faced with a knife tool ; then, as described
in Chapter Five, the central hole for the guide pin is
drilled to the required depth.
The two cutting lips are
formed by making a cut on the diameter with a fine
hacksaw, as shown in Fig. 8513, and at the same time the saw
FILE BOTH FACES
TO FORM CUTTING
EDGES
221
Fig.
86
is inclined to make the cuts slope in accordance with the
drawing.
If preferred, two further saw cuts can be made to remove
the su,rplus metal prior to filing the cutting lips to the
shape depicted in Fig. 85~.
Should an error be made when filing the lips to shape,
virus can be retrieved by again mounting the cutter in the
chuck and taking a facing cut across its end.
: When filing the lips, the edge of the file should make
“, contact with the vertical face of the cutting edge in order
,,t6 give it a smooth finish.
If a fine file is used for this
purpose, the edges will be quite sharp and oil stoning
after the cutter has been har~dened and tempered may not
,’ be needed.
The guide pins are made of silver-steel and there should
be no need to harden them as they are readily renewed
when worn ; in addition, there is no danger of an unhardened pin breaking when in use.
: Drilling Machine “Tab@ Stop. ’ This
device,
which
will be fou+a
tistiful addition&
~the,&-illing machine, is
228
illustrated in Fig. 14 in Chapter One, and the working
drawings from which it can be made are givtm here in
Fig. 86.
The collar, made of mild-steel or cast-iron to be in
keeping with ihe rest of the drilling machine, can usually
be machined from a piece of scrap material, but if this is
not available the part should be turned from a short length
of steel bar.
The turning operations involved are quite straightforward and consist in turning the outer diameter, drilling
and boring the part to make it a good sliding fit on the
machine column, and then parting off to the required
length.
The collar is finally drilled with a No. 22 drill, and
tapped to take the 2 B.A. clamping screw.
After the body of the clamping screw has been turned
and threaded as previously described, it is secured in an
inclined position in the machine vice. The hole for the
handle is formed by first entering the point of a fine
centre drill in a deep depression made with a centre
punch ; a small drill is then put right through the work,
and this is followed by a larger centre drill to make a
bearing for the No. 13 drill which enlarges the hole to the
finished size.
The next step is to grip the rod in the self-centring
chuck and part off the screw to the correct length ; the
screw is then reversed in the chuck and its end is faced
and finally rounded or chamfered.
The handle is made from a short length of & in. diameter
steel-rod which is held in the chuck of the lathe or drilling
machine, to enable one end to be slightly tapered with
the aid of a fine file. The vice is then used to press the
handle into place in the screw head.
A small pad, as shown in the drawing, is turned and
parted off from a length of brass rod ; this pad piece is
used to protect the drilling machine column from being
marked by the end of the clamping screw.
The Centrefinder or Wobbler.
A description of this
,,
229
appliance was given in Chapter Five, where it was also
illustrated ; the working drawings reproduced in Fig. 87
show the details of its construction.
It will be clear that the body piece (A) must be straight,
otherwise the indications given by then.device when in use
will be Ibisleading.
A piece of silver-steel rod should be used to make the
body, and its straightness can be checked by mounting it
either in the four-jaw chuck of the lathe or in a trueholding chuck in the drilling machine.
Although the
trained eye can readily detect any material wobble, it is
best to use the test indicator to take readings at various
points, and to repeat these tests with the rod reversed in
the chuck.
Moreover, if the rod is turned in the chuck
through an angle of 180 deg., and a second set of readings
is taken, errors arising from lack of truth in the chuck can
be eliminated.
Should there be any difficulty in finding a straight
piece of material, a rod should be turned to size in the
lathe using the travelling steady 2s described in Chapter
Five.
) The rod is centred in the four-jaw chuck and its end
is faced with a knife tool, set at centre height to avoid
forming a central pip ; the top slide is then set to 30 deg.
and the conical 60 deg. tip is turned to a sharp point.
Next, when the rod has been reversed and centxed in
the chuck, a 4 in. centre drill is fed in to form a parallel
bore for a depth of at least & in. ; a 4 in. drill is then
entered for the full length of the bore. The mouth of this
hole is opened out with a centre drill to form a guide
bearing for the drill used to enlarge the bore to its full
diameter.
If the drilling is carefully carried out it should be possible
to drill this hole accurately with a & in. drill, but if there
is any doubt about this, a smaller drill should be used
and the bore is then finished with a small boring tool.
To make the plunger (B), a length of silver-steel rod is
gripped in the chuck and turned down to make it an accur-
230
,.L ._------ L ----- -!b
iiryk--;-xvvvJigi=i+y
0
Fig. 87
ate sliding ,fit in the machined bore ; a centre drill hole
is then formed in the faced end, as shown in the drawing,
and the piece is parted off to the correct length.
The
plunger is next reversed in the chuck and the hole to
receive the spring (C) is drilled as previously described.
The length of the spring fitted should allow the plunger
to project as shown. TV secure the parts in position, so
that the plunger does not fall out, the ends of the spring
should be opened out with the pliers to give a firm frictional grip in both the plunger and the body piece.
Fit
the plunger to the spring by turning the former in a direction to close the coils of the spring, then insert the spring
in the body and continue turning the plunger until the
parts are correctly assembled.
An Angular Grinding Rest. The method of using the
angular grinding rest was described and illustrated in
Chapter Two, and the complete rest is shown in Fig. 88.
The rest is attached to the bench bv means of the angle
bracket (C), to which the swing ,arm (B) is secured by ;he
lower screw (D).
,,,,
,,
:,,,
At the upper end of the arm (B) the tilting work table
(A) is attached by the stud and nut (E) to the angle
bracket (F), which can rotate on the upper clamping
screw (D).
It will be clear that, when the two screws (D) are
slackened, the table can be tilted to any angle required
and, at the same time, the slot in the table can be set tb
clear the sides of the wheel.
IReference to the working drawings reproduced
in
Fig. 89 will show that both the angle brackets (C) and
(F) have been made of 4 in. angle-steel as this was the
only material available at the time, but stouter material
of & in. section might have been used with advantage.
The drawings of the bracket (C) show the position of
the screw holes for attachment to the bench, and also the
location of the tapped hole to receive the screw (D).
The length shown for the arm (B) may need to be altered
to bring the surface of the rest some distance below the
8
BSF
0
@
Eig. g8
,,
BSF
Fig. 39
:~,,,,
;;::
centre Ime of the wheel to allow for the thickness of the
‘::
tool being ground.
$Li,>
Both ends of the arm are drilled to give a working
;iT;
,,,,,,
clearance for the screws (D).
r;g,,
ST;,
The mild-steel table (A) should be made fully large to
:gj,:,, give adequate support for the tools ; the dimensions of the
g::,,
slot will depend on the size and thickness of the grinding
wheel fitted.
‘,‘~
The upper surface of the table should be tiled to a flat
finish so that the tools will lie evenly and without rock.
The table is attached to the angle bracket (F) by means
:!,I
:,,; ,,of a flush-fitting, stud (E) fitted with a nut and washer.
““““‘%
,,,,
,,,+:,~,’ ,’ For the fixing screws (II) either hexagon-headed
screws
can be used in accordance
with the drawing, or, if pre‘,,ferred, studs and nuts can be employed similar to (E)
only rather longer.
Tn the latter case, to give additional security, the inward
ends of the studs should be lightly riveted over.
TWIST
Inch or
gauge
80
79
as
78
77
76
75
74
73
ll7Ch
Inch or
gauge
0.0135
72
Decimal
mm
0.35
0.375
0.4
0.425
0.45
0.475
0.5
0.525
0.55
0.575
0.6
0.625
0.0138
0.0145
0.0148
0.0156
0.0157
0.0160
0.0167
0.0177
0.0180
0.0187
0.0197
0.0200
0.0207
0.0210
0.0216
0.0225
0.0226
0.0236
0.0240
0.0246
71
70
69
68
3%
67
66
mm
0.65
0.675
0.7
0.725
0.75
0.775
0.8
0.625
0.85
0.875
65
0.9
Decimal
Inch
0.0250
0.0256
0.0260
0.0266
0.0276
0.0280
0.0265
0.0292
0.0295
0.0305
0.0310
0.0312
0.0315
0.0320
0.032G
0.0330
0.0335
0.0344
0.0350
0.0354
DRILLS
Inch or
gauge
64
63
62
61
60
59
56
57
56
zih
mm
0.925
0.95
0.975
1 .oo
1 .o!i
1.1
1.15
1.2
1.25
1.3
Decimal
Inch
0.0360
0.0364
0.0370
0.0374
0.0380
0.0384
0.0390
0.0394
0.0400
0.0410
0.0413
0.0420
0.0430
0.0433
0.0453
0.0465
0.0469
0.0472
0.0492
0.0512
Inch or
gauge
55
54
53
3%
52
51
50
49
Decimal
mm
1.35
1.4
1.45
1.5
1.55
1.6
1.65
1.7
1.75
1.8
1.85
1.9
Inch
0.0520
0.0531
0.0550
0.0551
0.0571
0.0590
0.0595
0.0610
0.0625
0.0630
0.0635
0.0650
0.0669
0.0670
0.0689
0.0700
0.0709
0.0728
0.0738
0.0748
Jnch or
Gauge
48
7%
47
~,
g
46
45
44
43
41
,~,,~~
mm
1.95
Decimai
Inch
0.0760
0.0768
0.0781
inch or
Gauge mm
40
39
0.0785
2.00
2.05
2.1
2.15
2.2
2.25
2.3
2.4
2.45
0.0787
0.0807
0.0810
0.0820
0.0827
0.0846
0.0860
0.0866
0.0886
0.0890
0.0906
0.0925
0.0935
0.0936
0.0945
0.0960
0.0964
38
37
36
&i
35
34
33
32
2.5
2.55
2.6
2.65
2.7
2.75
2.8
2.85
2.9
2.95
3.00
Decimal
Inch
0.0980
0.0984
0.0995
0.1004
0.1015
0.1024
0.1040
0.1043
0.1063
0.1065
0.1083
0.1094
0.1100
0.1102
0.1110
0.1122
0.1130
0.1142
0.1160
0.1161
0.1181
Inch or
Gauge
31
4
30
29
28
&
27
26
mm
3.05
3.1
3.15
3.2
3.25
3.3
3.35
3.4
3.45
3.5
3.55
3.6
3.65
3.7
~3.75
Decimal
Inch
0.1200
0.1201
0.1220
0.1240
0.1250
0.1260
0.1280
0.1285
0.1299
0.1319
0.1339
0.1358
0.1360
0.1378
0.1398
0.1405
0.1406
0.14!7
0.1437
0.1440
0.1457
0.1470
0.1476
Jnch or
Gauge mm
25
24
23
3.8
3.85
3.9
3.95
2%
22
21
20
19
18
4.00
4.05
4.1
4.15
4.2
4.25
4.3
4.35
Decimal
Inch
0.1495
0.1496
0.1576
0.1520
0.1535
0.1540
0.1555
0.1562
0.1570
0.1575
0.1590
0.1594
0.1610
0.1614
0.1634
0.1654
0.1660
0.1673
0.1693
0.1695
0.1713
contd.
inch or
Gauge
mm
4%
17
16
15
!I2
0,
14
13
3%
12
11
10
4.4
4.45
4.5
4.55
4.6
4.65
4.7
4.75
4.8
4.85
4.9
4.95
Decimal
inch
0.1719
0.1730
0.1732
0.1752
0.1770
0.1772
0.1791
0.1800
0.1811
0.1820
0.1831
0.1850
0.1870
0.1875
0.1890
0.1909
0.1910
0.1929
0.1935
0.1949
Jnch or
&;iuge
mm
9
5.00
8
G
5
4
3
3%
2
5.1
5.2
5.25
5.3
5.4
5.5
5.6
5.7
5.75
Decimal
Inch
0.1960
0.1968
0.1990
0.2008
0.2010
0.2031
0.2040
0.2047
0.2055
0.2067
0.2087
0.2090
0.2126
0.2130
0.2165
0.2188
0.2205
0.2210
0.2244
0.2264
Inch or
Gauge mm
1
6.8
5.9
Gi
6.00
0
6.1
C
D
E. 3
F
G
6.2
6.25
6.3
6.4
6.5
6.6
6.7
Decimal
Inch
0.2280
0.2283
0.2323
0.2340
0.2344
0.2362
0.2380
0.2402
0.2420
0.2441
0.2460
0.2:461
0.2480
0.2500
0.2520
0.2559
0.2570
0.2598
0.2610
0.2638
Jnch or
Gauge
J-2
H
mm
6.75
6.8
6.9
I
J
sz
L
M
4-s
7.00
7.1
7.2
7.25
7.3
7.4
7.5
7.6
Decimal
inch
-
0.2656
0.2657
0.2660
0.2677
0.2716
0.2720
0.2756
0.2770
0.2795
0.2810
0.2812
0.2835
0.2854
0.2874
0.2900
0.2913
0.2950
0.2953
0.2969
0.2992
contd.
inch or
Gauge
mm
N
7.7
7.75
7.8
7.9
Pa
0
!i
P
8.00
8.1
8.2
8.25
8.3
ti
8.4
a
8.5
8.6
R
8.7
Decimal
Inch
0.3020
0.3031
0.3051
0.3071
0.3110
0.3125
0.3150
0.3160
0.3189
0.3228
0.3230
0.3248
0.3268
0.3281
0.3307
0.3320
0.3346
0.3386
0.3390
0.3425
Inch or
Gauge
33
S
T
mm
8.75
6.8
8.9
9.00
9.1
83
U
9.2
9.25
9.3
9.4
9.5
t
9.6
9.7
9.75
9.8
Decimal
inch
0.3438
0.3445
0.3465
0.3460
0.3504
0.3543
0.3580
0.3583
0.3594
0.3622
0.3642
0.3661
0.3680
0,3701
0.3740
0.3750
0.3770
0.3780
0.3819
0.3839
0.3858
Inch or
Gauge
W
9.9
5s
10.00
X
10.1
Y
33
10.2
10.25
10.3
10.4
2
10.5
10.6
10.7
Ei
Jnch
mm
10.75
10.8
10.9
11.00
11.1
0.3860
0.3898
0.3906
0.3937
0.3970
0.3976
0.40’16
0.4035
0.4040
0.4055
0.4062
0.4094
0.4130
0.4134
0.4173
0.4213
0.4219
0.4232
0.4252
0.4291
0.4331
0.4370
3%
32
3-3
34
rnr.:
11.2
11.25
11.3
11.4
11.5
11.6
11.7
11.75
11.8
11.9
12.00
12.1
12.2
12.25
12.3
124
12.5
12.6
Decimal
Jnch
0.4375
0.4409
0.4429
0.4449
0.4488
0.4528
0.4531
0.4567
0.4606
0.4626
0.4646
0.4685
0.4688
0.4724
0.4764
0.4803
0.4823
0.4842
0.4844
0.4882
0.4921
0.4961
contd.
Decimal
Jnch
m/m
Inch
12.7
12.75
12.8
12.9
13.00
0.5000
0.5020
0.5039
0.5079
0.5118
0.5156
0.5216
0.5312
0.5315
0.5413
0.5469
0.5512
0.5610
0.5625
0.5709
0.5781
0.5807
0.5906
0.5938
0.6004
13.25
13.5
13.75
14.00
14.25
14.5
14.75
15.00
15.25
inch
m/m
15.5
15.75
Q
16.00
16.25
16.5
16.75
17.00
17.25
is%
17.5
17.75
18.00
18.25
18.5
Decimal
inch
0.6094
0.6102
0.6201
0.6250
0.6299
0.6398
0.6406
0.6496
0.6562
0.6594
0.6693
0.6719
0.6791
0.6875
0.6890
0.6988
0.7031
0.7087
0.7185
0.7188
0.7284
Inch
34
mlm
18.75
19.00
a
19.25
+Ei
5%
%I
4%
%-s
3-z
19.5
19.75
20.00
20.26
20.5
26.75
21 .oo
21.25
21.5
2.751
Decimal
Inch
0.7344
0.7382
0.7480
0.7500
0.7579
0.7656
0.7677
0.7776
0.7612
0.7874
0.7969
0.7972
0.8071
0.8125
0.8169
0.8268
0.8281
0.8366
0.8438
0.8465
0.8563
Inch
3s
L
8
s-8
23
E
+E
&
it??
+?
m/m
22.00
22.25
22.5
22.75
23.00
23.25
23.5
23.75
24.00
24.25
24.6
24.75
25.00
Decimal
inch
0.8594
0.8661
0.8750
0.8760
0.8858
0.8906
0.8957
0.9055
0.9062
0.9154
0.9219
0.9252
0.9350
0.9375
0.9449
0.9531
0.9547
0.9646
0.9688
0.9744
0.9842
0.9844
1 .oooo
A
Abrafile. 22, it%
Angle-Poise Lamp, 9, IO.
A”& Plate, 55.
Angular Grinding Rest, 139-141.
templates
11
1,
” for 143.
,, m&“g an
.,
.1
230-233.
Dimensions, 65.
Dividers. 48, 49.
DrayFiling, 70-72.
D;,;r5s,
Conventions used in,
Bakers’ Fluid, 9;
Belt Pulleys. 165-167.
Be;;;tenws,
Round Belt, 119-
14%
Dra$ngs,
Drill Gauge, 46, 41.
Drill Pad, 157
Drills Grinding, 144-146..
7,
71 PO;& Jig,
Chuck, 126.
” Chuck Lathe 157.
D&s, Hand, 22-24:
Straight Fluted, 24.
1: Twist, 24.
Drilling with Hand Drill, 85-88.
Drilling Machine, Depth, Stop
and Gauge, 127-128..
I$y2;
the,
0
3.
B&s. v, 165-166.
Be”ClXS, 2. 3.
Blue Marking Compound, 73. 74.
Boring. 190.
7, Bar, 200-201.
I. Work on the Saddle 2OO201.
r
Callipers, 41.43.Jennv. 49.
Case:‘Hardeni”k: 99.
Centre Finder, 185-186.
.,
.1 Making a, 228230.
Centre Lines. 64
Pun&, 49, 50.
C&es, Lathe, 198-199.
Chests of Drawers, 6, 8.
Chisels, 30. 31.82-84.
Chucks, Drill, 126.
>, Four-jaw, 155-1.56.
Self-centring, 155.
..
SettirygWork in, 184-186.
I,
Tu,rrg
Work in, 186.I
:‘,,
‘, ‘,
Reading Machine, 60.
Use of, 184-192.
CL& Vice, 13.
Colleted Die-holders, Making.
21 l-219.
Conventions used in Drawings,
61-65.
Cupboards, 2.6. 8. 9.
Counterbores, 134.
and Pin Drills,
*,
Making, 223224.
Countersinks, 132-133.
Making, 223-224.
Cou”te<hhaft, 165-166.
Speeds, 165.
Cross-dr?lling Shafts, 131-132.
Cut, Depth of, 183-184.
Cutting Speeds,;82-183.
,I
I>
.*
II
3,
0
,.
. .
1,
33
0
7.
.,
1.
.,
9,
163: 176.
Eiectrlc, 118.
Equipment,
I23- 127.
Lever Feed,
109-112.
Feed,
Rack
112-l 16.
Table
stop.
126.
Table
stop,
Making. 227.
Table V-blocks
124-125.
Tapping
Handle For,
219.223-228.
Tw34t-;p the.
Vice. 123-i24.
Work Clamp,
125-126.
Machines, Ch;,y-pion,
I.
..
,.
,,
Model
Engineer,
109-112,
I IY.
Wolf, 118.
,,
0
Coweli,
Driiiing She;; Metal, 116-l
88. 18.
>.
(8
‘Drilling for Tapping,, 132.
9% frcmn2the Tadstock, 2019.
D-bit, 203.
Depth Drilling, 202-203.
Depth Gauge, 45.
simple,
I.
7, M;kfo;,
int;?a Cross Hole, 130.-..
on a” Inclined Surface,
130,131.
I, Operations, 128-134.
Speeds, 120-i23.
D&&g the Drilling Machine,
118-120. 163, 170.
,,, , ,, Lathe, 152-154.,
3.
Dies, 25-27
Diey&
Tapping in the Lathe,
Die Hold&s, 27.28.
1 ’ Die Hoi&t%, Making Colleted,
,2! I-219.
239
IN&
240
E
Electric Drilling Machine.1 18.
138-I39.
3. Grinding
Motor D&to
Machine
I.
Tool~,,l63-172.
Equipment, Drdlmg
123-127. Machi”e*
I,
Lathe, 154-162.
Eq4$*
for Marking-out, 41Equipment for Screw Threading,
24-28.
Equipment for Soldering, 38. 39.
Workshop, 12.40.
1,
Use ,“f 192-195.
Feed Gear, Lathe: 150-151.
Feed, Rate of, 183.
Files, 16-19.
File Card. 70.
Handles, Fitting, 18.
FYling,66.
>, Alum&urn, 72.
Draw-, 70-72.
Fiied Steady, 158-159.
Floor, The Workshop, 10.
Flux, Solder&!, 95.96.
Fom-jaw Chuck, 155-l 56.
Four-tool Turret, 157-158.
G
Gauge, Depth, 45.
a Simple Depth, 100-103.
9,
..
Drill. 46. 47.
surface 55.
G& Feed, ISO-‘151.
Graver, 208-210.
Grinding Machine, 135-138, 167.
9%
Dr,l;g37the.
.,
t%?Ceplate,
Jenny CaIlipers.~9.
Lamps, Angle-Boise, 9, IO.
Lathe, The, 147.152.
,, Accessori~!, 154-162.
‘, Centres, 198-199.
,, Chucks, 155-157.
9. Dogs, 197.198.
,, Drill Chuck, 157
Driving the, 152-154.
1: Equiprwnt, 154-162.
,, FeedGear, 150-151.
,, Half Centres, 198-1999.
,* Hand Turning Tools, 207.
210.
., Headstock, 149.
,, Saddle, 149.
,, Tailstock, 150.
Tools, 173-178.
L&I, Spirit, 16, 86.
Lighting the Workshop, 9, 10.
Lines, Witness. 53.
Lineshafting, 163-164.
M
Machine Drawings, Reading, 6003.
Machine Tools, Driving the, 163172.
Marble SIab, 4-6.
Marking-out. 47-59.
..
1, a Bearing Bracket,
56-59.
,, Ce;;? of a Shaft,
.I
3.
.*
__
167, 17d.
Electric, 138”
139.
Black &
Decker
138-139.
Grinding Operations. 142-144.
0 Rest, Adgtdar, 139-141.
*.
., AIlgUIX Templates
for, 143.
Angular,
1,
., M;din;3y
.1
1.
3.
,, Twist Drills, 144-146.
Jig for,
., Twist DIrr;lsxts
Hacksaw, 19-21?
Blades, 19, 20.
0
Using the, 76, 77.
Ham;;lers, 37.
Hand Drills, 22-24.
Hand Rest. 160-161.
,, Tools. 16-40.
musing, 66-99.’
1: T&ing Tools. 207-210.
Handles, Fitting File, 18.
Httrdenmg and Tempering, 98.99.
Headstock, Lathe, 149.
Heating the Workshop, 2.9.
__.
Solid Objects. 54.
Fluid, 48.
Mea&ng’instruments,
178-182.
Metal Cutting, 79-85.
,.
.. with Shears, 82.
Cold Chisels.
3.
,1
ii2-85.
Metal Sawing, 74-76.
Micrometer, 178-180.
Micrometers, 45.
N
Nu~~-Bolts and Screws, Storing.
Nlitsj,Bolts
1,
9.
*. Equipment, 41-49.
,, Sh~eeS~tal Work,
31
0
Oilstone, Slips, 177.
Stoning Jig for. 177-I 78.
Oiliiones, 40.
Operations. Drilling, 128-134.
Grin$ing, 142-144.
0
Tury& 182-200.
Turyg,
3.
Pin Drills, Co~nterbores and,
225-227.
Pinning, 70.
Pliers, 36, 37.
Polishing with Hand Drill, 88.89.
Fvotr2ctor. 46.
Pulleys, Belt, 165-167.
Punches, Came. 49.50.
Pin, 38.
,I
241
INDEX
T
Tailstock. Lathe, 150.
0
Die-holder, 205-206.
3.
D;llFg from the. 201-
Rack?., Tool, 2, FE.
fQQ+$
Reaming, 89-90.
Rest, Hand, 160-161.
Rules, 44.45.
Rule Stand, 55.
Making a
1. 0
103-107.
Rust, PreventionSof, 9.
Simple,
Saddle, Lathe, 149.
Saws. 19-23.
Abrafile. 22.
S&s, “Eclipse” Light Wttem, 21.
,, Fret, 22.
,, Hack, 19-21.
Piercing, 21-22.
1: Curves. 78.79.
Sawing Metal, 74-76.
,, Marking-out
I,
Work for, 76.
scrapers, 31.32.
Sharpening, 74.
S&ping, 72-74.
Screwdrivers, 34, 36.
Screw Cutting, 206.
External,
.,
(3 Tool,
176.206.
Internal.
9.
7. Tool,
207.
screw Threads. 62,6X
3.
>B Cu~anng,Extemal.
,.
.*
CG&.
Tapping, Drilling for, 132-133.
*I Handle for the Drilling
Machine, 219, 223228.
9% in the Drilling Machine.
132-133.
Taps, 26.
Tap Wrenches, 27.
Tempering, 98.99.
Test Indicator Dial, 181.
IEII.
.I “Unique”,
182.
Threads Cutting, 90-95.
,.
II External, 94,95.
lntemal. 90-94.
Tin&n’s S&s. 28.
Tool Racks, 2,6-E.
Tools, Hand, 16-40.
Tools, Lathe. 173-178.
207,.
.I Ha$Tuming
-_..
Using Hand, 66-99.
T&ing Operations, 182-Z@%
,, Tools, 173,-178.
Turrets, Four-tool, 157-158.
Twist Drills, 24.
Twist Drills Taties of, 234.
Internal,
Scygw Threading Equipment, 24-._.
Scriber, 48.
Seif-centring Chucks, 155.
Shafts, Cross-drilling, 131-132.
Shears, 28,29.
Tinman’s, 82.
Sh&ing Machine, 29.
Shelving, 8.
Slab.
4-6.
---.-r Marble.
~~
Snips, Tinmad’s, 28.
Soldering, 95-98.
Equipment, 38, 39.
..
Flux, 95. 96.
1,
Irons, 38. 39.
Spar;;len. 32-34.
Speeds, Cutting, 165.
-1 DriEng Machine. 120123.
I. Countershaft, 165.
$$s4!ixed
158-159.
.. ’ Us& Fixed, 196.
TravelSing, 159-160.
9,
Usiig, Traveliing, I99I.
stoness.oil, 40.
Storing, Screws. Nuts and Bolts,
6-7.
Stoning Tools, 6-8.
Straight FLU@ Drills, 24.
surfaa Gauge, 55.
),‘, :Platc, 55.
V-Belts, 165-166:
V-Block, 56..
v-&lo&~5Drdlmg MachineTable,
Vice.
,,
,,
,,
::
,,
12.
Clams, 13.
Correct Height for. 15, 16.
Drilling Machine, 123-124.
Jaws, 12,
Fixing
the.13.
14, 15.
Yankee. 16.
w
Witness Lines, ii-58.
Work Clamp, Drilling Machine,
125-126.
Workshop Equipinent, 12-40.
Floor. 10.
W&aches, Tap, 27.
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