The Lathe Bed - Vintage Machinery

The Lathe Bed - Vintage Machinery
REVERSING SWITCH
HEADSTOCK
•I
FIGURE 1-LOGAN NO. 920 FLOOR MODEL 11 " SWING QUICK CHANGE GEAR LATHE
2
LOGAN LATHES
.,
It is of the greatest importance that the lathe be level; if
it is not. its weight will cause the lathe bed to be twisted,
throwing the lathe out of true. It is impossible to do accurate work on a lathe that is not level and the lathe will
be damaged beyond repair.
The cases in which your Logan Quick Change Gear Floor
Model Lathe is delivered contain the following:
l Logan Lathe with headstock. tailstock. and carriage
mounted on the lathe bed
2-step V type motor pulley (screwed to base of lathe
crate)
Bag tied firmly to lathe bed containing
l tool post
tool post ring
l tool post screw
l tool post wedge
l tool post block
l tool post wrench
l tailstock wrench
2 60° centers
l Headstock Adapter Sleeve
l knob and quill
Countershaft assembly-floor type
V Belt (attached to countershaft)
Six conductor cable (in bag attached to headstock)
Instruction book (inside the change gear guard)
Parts List (inside the change gear guard)
Chip pan
Set of floor legs
When the lathe is in position, place a sensitive machinist's level on top of the lathe bed and adjust any variation from level by placing thin shims under the feet.
Be certain the lathe is level across the ways and parallel
to them, both at the headstock and tailstock ends. When
the lathe is level bolt down tightly and check the leveling. It may be necessary to loosen the bolts and add
more shims. Remember the lathe must be level if it is to
perform accurately.
BENCH MODEL. Attach the countershaft assembly and
place the lathe in position on the bench. The bench for
the lathe should be 31 to 33 inches high of heavy construction and suitably reinforced for steadiness and
should have a top of seasoned wood at least two inches
thick. We suggest that the top either be doweled or that
4 or 5 steel rods with end nuts be run crosswise through
the top and the nuts turned tight. pulling the boards together. Plane the bench top level and place the lathe
upon it. Mark and drill four %-inch holes under the r.orresponding holes in the legs at each end of the lathe.
Through these holes place four machine bolts to fasten
the lathe to the bench and to aid in leveling. Then proceed to level the lathe bed with shims as described above
for the floor model.
For the Bench Model Lathe the chip pan and floor legs
are omitted and the countershaft assembly will be the
bench type instead of the floor type.
Unpack carefully and check to be certain that you have
removed all the pieces. After removing the lathe from
its shipping case, clean it thoroughly with a stiff brush
and kerosene. Then cover all the unpainted surfaces with
a film of good machine oil to prevent rusting. These surfaces should be covered with a film of oil at all times and
the lathe should be covered with canvas when not in use.
Mounting the Motor
The Logan Lathe is designed to be powered by a 1750
RPM motor. When the lathe is in place mount the motor
on the motor bracket beneath the countershaft. Do not
tighten bolts until the motor position has been adjusted.
Setting Up the Lathe
FLOOR MODEL. Mount the lathe on the chip pan and
the floor legs, using the bolts furnished, and attach the
countershaft assembly to the rear of the headstock as
shown in Fig. 2. When mounting the lathe on the pan
and legs, notice that the holes in the pan are not drilled
an equal distance from the sides of the pan. The short
side is to be mounted towards the back of the lathe to
keep the pan from interfering with the motor. Locate
the lathe on a solid level floor. preferably concrete, in a
dry well lighted location, using lag screws or bolts to
fasten the legs to the floor. If the lathe is set on a concrete floor, mark the location of the bolt holes and drill
in the concrete with a star drill setting the lag screws or
bolts in expansion shields or in melted lead.
To adjust the motor position, align motor pulley and
the pulley on the countershaft by moving the motor until
the two are in line. Tighten the base bolts, but do not
place the belt on the pulley until the motor wires have
been connected and the motor pulley tested for direction
of rotation.
Connect the drum reversing switch mounted on the
countershaft with the motor, using rubber covered 6 conductor cable in accordance with the wiring diagram
pasted on the inside of the switch cover. Motors furnished
by Logan have a wiring diagram packed with the motor
to assist in making the proper connections. Connect the
3
RU BBER INSULATED
SU PPO RT PIN
motor to the current source. The motor pulley should then
rotate clockwise, viewed from the motor pulley end,
when the switch is in the forward position. Combined
switch and motor wiring diagrams are shown on the last
page of this booklet for use with the motors we furnish.
We recommend the use of a good three phase motor
that is electrically balanced and will not transmit vibration through the belts to the headstock, causing chatter.
Split phase motors are not recommended, especially
where fine work is required.
MOTOR CONTROl
SWITCH
GUARD FOR CONE
PULLEYS AND FLAT BELT
RUBBER
TIPS
GUARD
FOR
2-STE P
PULLEYS
AND
V BELT
Adiusting the Belts
The belt from the motor to the countershaft and the one
from the countershaft to the lathe are easily adjusted
for tension. Neither of these belts should be too tight.
the tension depending on the load. Excessive belt
pressure will shorten the life of the belt, place a strain
on the bearings and cause a loss of power through
excessive friction. When adjusted for normal work a
moderate pressure on the middle of either belt should
depress it about l Y2 inches.
The motor bracket is hinged at one side with a bolt
and nut adjustment that raises or lowers it, thereby
decreasing or increasing the tension on the V belt.
The V belt rides in a V groove of the two step motor
pulley and on a flat face of the two step countershaft
pulley.
FIGURE 2-END VIEW OF COUNTERSHAFT ASSEMBLY
easily. An adjustable motor mounting bracket is included in the assembly. All pulleys and belts are completely guarded, yet easily accessible. A patented
tension release operates automatically when the cover
for the cone pulleys is raised to permit quickly changing the flat belt from one step to another. And finally,
the entire assembly is designed to appear as a streamlined part of the lathe.
When the cone pulley guard is raised, the countershaft
automatically moves toward the headstock, thereby
releasing the tension on the flat belt. With the tension
released, the belt may be easily changed from one step
to another. When the cone pulley guard is closed the
belt is automatically brought into tension again, the
amount of tension being regulated by a slotted head
screw located at the rear of the cone pulley guard.
Turning the screw to the right increases the belt tension;
to the left decreases it.
Fig. 2 above illustrates the floor model lathe and
countershaft assembly in position. The bench model uses
the same countershaft design adapted for bench use.
The Headstock
The Countershaft
The headstock of the Logan Lathe is made of high grade
gray iron and is totally enclosed. It contains the
headstock spindle and bearings, the bull gear, the cone
pulley and the back gears. The cone pulley is turned
by the belt from the countershaft, and thereby turns the
bull gear, or transmits its power through the back gears
to the bull gear if lower speed or greater power are
desired.
The countershaft assembly of the Logan Lathe is a
patented development that is a distinct improvement
over previous design. This special unit assembly is
carried by two hinged pins attached to a bracket in the
headstock and by a pedestal to the floor or the bench
giving three point suspension. To prevent vibration being
transmitted to the lathe, the entire assembly is insulated
by rubber at all points of contact. The two hinge pins
are rubber cushioned and the cone pulley guard rests on
rubber buttons. Provision is made to adjust belt tension
High carbon machinery steel has been used in making
the spindle, which has been machined and ground to a
fine finish. The nose is 2 ¥4-in. diam. with 8-pitch National
Form threads.
4
ruff key, collar, and bearing grease seal in the order
named from the left hand end of the spindle.
Second, remove the four fillister head screws from the
bearing cap, then the bearing cap and next the grease
seal from the right hand end of the spindle.
GUARD
MOTOR DRIVE
GUARD
CONE
COUNTERSHAFT
PUllEY
Third, loosen the set screws in the bull gear and carefully drive the spindle with a wooden mallet toward
the tailstock end of the lathe, being careful to hold the
bull gear and cone pulley parts as the spindle is removed so they will not drop.
CONE PINION
GEAR
Important
Ball bearings can be ruined by improper handling.
When pressing a bearing into or out of the seat. pressure
should be applied to the outer race only, but when
pressed on to or off of shaft, pressure should be applied
on the inner race only. Bearings should be carefully kept
free of dirt and grit and except in extreme cases should
not be tapped into place with a he-mmer.
The Back Gears
FIGURE 3-HEADSTOCK AND COUNTERSHAFT
~
A reducing sleeve permits the use of a No.2 Morse Taper
Center. The 1%-in. hole permits work as large as l-in.
to be fed through the spindle. A draw-in collet attachment taking collets up to l-inch capacity can be used
through the hollow spindle.
The spindle is mounted on two New Departure precision
ball bearings which are sealed in grease. The use of
ball bearings in the headstock to mount the spindle is
advanced design that, although more expensive, gives
finer results. Ball bearings are the ideal frictio.1 reducing
bearings-"nothing rolls like a ball." Technical advances
in ball bearing manufacture make it possible now to
obtain special pre-loaded ball bearings of extreme precision that will carry the loads for which they are designed with less wear, greater accuracy and with no
adjustment required.
FIGURE 4-BACK GEAR DRIVE
The back gear mechanism on the Logan Lathe is enclosed in the headstock instead of being located in an
exposed position as in the usual construction. Also,
instead of having to reach over the top of the headstock to throw a back gear lever, the Logan design
permits controlling the back gear by a knob on the
front of the headstock. The back gear is mounted on a
quill which turns on self-lubricating bronze bearings
on an eccentric shaft. The knob operates a rack engaging
a pinion which rotates the eccentric shaft, thereby swinging the back gears into mesh. When the knob is pulled
out, the back gears are engaged and are locked in posi-
The three-step cone pulley and the cone pmwn gear
are fastened together rigidly and revolve freely on the
spindle. For direct drive, the pulley is locked to the large
bull gear which is keyed to the spindle. This is accomplished by means of a plunger-type lock located on the
side of the bull gear. When this lock is "in" the pulley
turns the bull gear with it; when "out" the pulley and
the cone pinion gear turn iree of the bull gear.
Should it ever be necessary to remove the headstock
spindle the following procedure should be followed_
First, remove the take-up nut. the spindle gear, Wood-
5
tion by a pawl just back of the knob. The lock is released
by pressing the pawl with the finger.
The Lathe Bed
The cone pulley and small gear turn freely on the
spindle and are locked to the bull gear for direct drive
by a lock pin located in the side of the bull gear. When
slower turning speed or greater power than could be
obtained from a direct drive is required, the back gears
are used. To engage the back gear drive first pull out
the direct drive lock pin so that the cone pulley and
The bed of the Logan Lathe is an extra heavy one-piece
casting Df hard iron containing the correct proportion
of steel and alloys to give the maximum in wear and
to withstand all strains. Extra width (6-15 16" across
cone pinion gear tum free of the bull gear. Then engage
the back gears so that the power is transmitted through
the cone pulley and cone pinion gear to the large back
gear, and from the small back gear to the bull gear.
The bull gear, being keyed to the lathe spindle, turns
the spindle.
SET·OYER SCREWS
Spindle Speeds
MOTOR
COUNTERSHAFT
FIGURE 6-LATHE BED AND TAILSTOCK
the ways) extra heavy walls, heavier and closer spaced
box type cross ribs combine to give greater strength
and a more solid foundation for the lathe mechanisms.
The accuracy of the lathe bed and the ways on which
the carriage and the tailstock are mounted is of primary
importance. To insure extreme accuracy in the bed two
prismatic V-ways and two flat ways are employed. They
have been planed, milled and precision ground, giving
an accurate, heavy. well ribbed bed of the type found
on large engine lathes. In order to retain this accuracy.
the instructions for setting up the lathe emphasize the
necessity for carefully levelling the bed both across
and parallel to the ways.
SPINDLE
OF LATHE
FIGURE 5-BELT DRIVE DIAGRAM
The following table shows the spindle speeds which
can be obtained using the various belt positions shown
in Fig. 5, both with direct drive and with the back gear
drive.
Motor
Belt
Position
2
With proper care and normal use there will be no
appreciable wear on the bed or ways of a level lathe,
but the surface may be damaged by a lack of oil or
by abrasion. Be careful not to drop tools or work on
the ways. Keep them well oiled when not in use, wiping
them off and re-oiling before continuing work and, if
possible, keeping them covered during filing or grinding operations.
Spindle Belt Position
Direct Belt Drive
Back Gear Drive
4
3
45
4
63
5
89
3
270
380
5
535
125
177
250
753
1060
1500
6
STUD
GEAR
LEfT
HAND
LEVER
48
A
24
A
8
9
10
11
24
24
24
B
16
32
64
18
36
72
20
40
80
22
44
88
c
D
THREADS PER INCH
7
11 Y2 12
23
46
92
13
14
24 26 28
4 8 52 56
9 6 104 1 1 2
24
LEVER POSITIONS
E
128 144 160 176 184 192 208 224
LONGITUDINAL TURNING FEEDS
48
A .1000 .0888 .0800 .0728 .0696 .0666 .0616 .0572
24
A
24
8
24
c
24
D
24
E
.0500
.0250
.0125
.0062
.0031
.0444
.0222
.0111
.0055
.0027
II
.0400 .0364
.0200 .0182
.0100.0091
.0050 .0045
.0025 .0023
II
II
.0348 .0333
.0174 .0166
.0087.0083
.0043 .0041
.0021 .0020
II
II
.0308
.0154
.0077
.0038
.0019
.0286
.0143
.0072
.0036
.0018
II
II
FIGURE 7-THREAD AND FEED CHART ON LOGAN QUICK CHANGE GEAR LATHES
IDLER
GEAR
feeding. The rate of feed is dependent upon the speed
of the lead screw.
It is necessary in operations such as thread cutting to
set the rate of feed in a definite relationship to the speed
of the spindle. This is done by the selection of gear sizes
in the gear train together with the setting of the levers on
the quick change gear box.
24 T GEAR
IN STUD
POS!TlON
!1'1 ... I
It is possible to obtain 48 different threads or feeds in
either direction on the Logan Quick Change Gear Lathe.
For threads from 8 to 224 per inch, inclusive, the change
gear train is set up as in Fig. 8, using the 24 tooth stud
gear. A 48 tooth gear is mounted as a spacer on the
idler gear but serves no active purpose. For threads from
4 to 7 per inch the 48 tooth gear is mounted in the stud
gear position and the 24 tooth gear is mounted as a
spacer on the idler gear.
SCREW
GEAR
All other adjustment for the various thread or feed requirements is made by the two levers on the quick
change gear box. Fig. 7 shows a reproduction of the
thread and feed chart mounted on the gear box. As an
example, assume that the 24 tooth stud gear is engaged
in the change gear train (with the 48 tooth stud gear
being used as a spacer) and that it is required to cut
18 threads per inch. Locate 18 on the gear chart. Set the
left hand lever in position "B" as indicated and set the
right hand lever directly under the column in which 18
appears. Similarly, if a longitudinal feed of .0045 inches
per revolution d the spindle is required, set the left hand
lever in position "D" and the right hand lever under the
column in which .0045 appears.
QUICK CHANGE
GEAR LEVERS
FIGURE 8-CHANGE GEAR TRAIN ON LOGAN QUICK CHANGE GEAR LATHE
Power Feeds
The left end of the headstock spindle is fitted with a
gear for the transmission of spindle power through a gear
train and through the quick change gear box to the lead
screw along the front of the lathe which is used in power
7
Power cross feeds are .25 times the chart figures shown
for power longitudinal feed.
for a No. 2 Morse Taper Center.
for a No. 2 Morse Taper Center.
The tailstock is fitted
The feed reversing lever, which extends from the gear
train housing has three positions-Up, Down, and Center.
When in the center position the two gears on the end of
the lever, which turn on bronze bearings, are free of the
gear train and all power feeds are disconnected.
When "Up;' the lead screw turns to move the longitudinal
and cross feeds in one direction. When "Down:· the longitudinal and cross feeds are in the opposite direction.
FIGURE 9-60 DEGREE C.ENTER
The alloy steel lead screw which runs along the front of
the lathe bed has an Acme thread accurately cut with a
pitch of 1/a inch (8 threads to an inch) and is mounted at
each end in a bearing. Clean and oil the lead screw
frequently to maintain its accuracy.
While the tailstock spindle should be kept oiled on
the outside, the interior should be dry and clean. Before placing either of the centers in the lathe, they and
the tapers into which they fit should be wiped free of
oil and dirt, for the presence of a bit of dirt or a slight
film of oil will interfere with the accuracy.
The Tailstock
The tailstock slides on a V and flat way 0f the bed
as illustrated in Fig. 6. It is locked in position along
the bed by tightening the clamp bolt with the clamp
bolt wrench furnished with the lathe.
The Carriage
The tailstock spindle is controlled by the tailstock hand
wheel. Turning the wheel in a clockwise direction brings
the spindle out of the tailstock. The spindle is of special
steel with a ground finish and has been reamed for a
No. 2 Morse Taper Center, which may be ejected by
turning the tailstock wheel in a counter clockwise direction until the spindle reaches the end of its travel.
HAND CROSS
FEE D
APRON
The spindle is graduated up to 4 inches in sixteenth
inch graduations for accuracy in boring and drilling .
Lock spindle in place by turning the binding lever to the
right. A cup and quill are mounted on the top of the
tuilstock. Fill with a heavy grease or a mixture of white
lead and machine oil to be used to lubricate the centers
when work is mounted between them.
FRIGIO N
POW ER FEED
ClUTCH
LE VER
FIGURE 10-CARRIAGE
The carriage of the lathe is made up of four parts, the
apron assembly, the saddle assembly, the compound rest
assembly and the tool post assembly. Since the carriage
supports the cutting tool and controls its action it is an
important unit.
The tailstock may be set-over 11 ' 16 inch for turning
tapers by loosening the tailstock clamp nut and adjusting the headless set screws located on either side. To
align the tailstock again the index line on the tail stock
and tailstock base will indicate the approximate posiion. To obtain the exact position it is necessary to place
a 12 or 15 inch check bar between centers. Take a light
cut, then check the diameter at each end of the bar with
a micrometer. If there is a variation adjust the set-over
screws until the diameters at each end are the same
after a cut.
APRON. The apron which is suspended from the front
of the saddle contains the power feed mechanism and
the longitudinal hand feed together with the threading
dial.
The large hand feed wheel on the front of the apron
moves the carriage along the ways by means of gears
which engage a rack on the underside of the front way.
The power feed lever is located in the center of tl:e apron
and ca n be set in three positions. When "Up; ' the apron
mechanism is set for power longitudinal feed; when
"Down:· for power cross feed , and when in the central
Lathe Centers
The headstock spindle is ground to take a special adapter
8
The compound rest is mounted on top of the cross-slide
on a base calibrated in degrees from 0° to 90 ° in both
position, is in neutral. To engage the power after having
set the power feed lever in the required position, the friction clutch knob located immediately below is turned
to the right. Similarly, it is turned to the left to disengage.
The feed reverse lever on the headstock controls left or
right longitudinal feed, and forward and backward movement of cross feed.
directions. Two screws with tapered plugs, one on each
side of the rest, hold the base in position, and by loosening these screws the rest may be swivelled to the desired angle. Two self-lubricating bronze bearings are
mounted in the bushings of the rest which is moved over
the slides by an Acme threaded screw. The slide is dovetailed with qib take-up for wear.
In thread cutting, the half nuts are used for longitudinal
feed. The half nut lever is located at the right side of the
apron. The half nuts can only be engaged when the
power feed lever is in the neutral position, and also the
power feed lever cannot be engaged while the half nuts
are engaged.
Power is fed through the friction drive from the spline
in the lead screw, whereas the half nuts drive from the
lead screw thread. To minimize wear and thereby retain
the accuracy of the half nuts and lead screw, they should
only be used for thread cutting.
The threading dial on the right end of the apron indicates
the proper position in which to engage the half-nuf
lever during threading operations so that the tool will
enter the same groove for each cut, thereby eliminating
the need for reversing the drive at the end of each cut.
(Fig. ll Threading Dial.)
When cutting even numbered threads, the half nuts may
be engaged at any point on the threading dial.
FIGURE 11-THREADING DIAL
When cutting odd-numbered threads (5, 7, 9, ll, etc. per
inch), engage the half-nut lever when the outer mark
is in line with either the mark numbered 'T' or that
numbered "2:'
The compound rest motion is controlled from a hand
wheel by which the tool may be moved into the work
for short tapers. The compound rest handle is calibrated for measurement in thousandths of an inch.
When cutting half-numbered threads (4Y2, SY2, 6 Y2, ll Y2,
etc.). engage the half-nut lever at the same point on the
dial for each cut.
The tool post fits into a T slot in the compound rest and
holds the tool holder by means of a square head screw.
The saddle, which moves longitudinally on the front
V-way and the back flat way, has been machined from
a semi-steel casting, and is held down on the bed by
gibs which bear on the underside of the front and back
ways. These gibs are adjustable and should be set just
tight enough to give a firm sliding fit between the carriage and the bed.
Oiling the Lathe
The design of the Logan Lathe provides for correct
lubrication with a minimum of attention. The ball bearings in the headstock are sealed in grease and require
no further lubrication for the life of the bearing. At
31 separate points there are self-lubricating bronze
bearings, where in ordinary construction plain bearings
with oil holes are used. The bronze in these bearings is
of an absorbent texture and has been thoroughly impregnated with lubricant. The correct film of lubricant
is constantly maintained at the bearing surface without
the necessity of frequent renewal.
The compound rest base moves across the top of the
.saddle on dovetailed ways to form the cross slide. The
hand cross feed is operated by a hand wheel at the end
of the cross feed slide. This slide is equipped with a gib
which may be tightened by adjustment of the set screws
on the outside of the s lide. The cross feed gib should fit
snugly and should be a d justed whenever play develops.
The cross slide is moved by a n Acme threaded screw
mounted in self lubricating bronze bearings. The hand
wheel of the cross feed is of polished steel and is calibrated in thousandths of an inch for measurement of
feed when a definite cut is to be taken.
Those points in the lathe requiring regular lubrication
should be gone over every time the lathe is used and in
a definite order so that no parts will be missed. Use a
good machine oil no heavier than SAE No. 10, wiping
away excess oil that would cause dirt to adhere to the
lathe. Do not attempt to oil the lathe while it is running.
9
6
FIGURE 12-0ILING DIAGRAM
Keep the following surfaces clean, free of chips and
covered with a film of oil:
The lead screw.
The cross slide.
The compound slide.
The lathe bed ways, both V and flat.
The outside of the tailstock ram.
Spindle taper ~rea.
Using a long-spouted can, oil the following points each
time the lathe is used:
1.-2.
3.
4.
5.
6.
7.
8.
Two oil cups on top of the countershaft bearings.
The spring well on top of the tailstock.
One oil cup on top of the bearing at right end
of the lead screw.
The feed reverse lever. (A hole has been drilled
in the base of the lever to receive oil.)
The bearings on each of the change gears.
The spindle pulley. (Remove the headless set
screw on the 3econd step of the pulley and oil
freely before using the back gears.)
Remove set screw and fill this oil ·well so that
when petcock set screw (9) is removed, oil just
drips out.
A small amount of graphite grease should be kept on
the teeth of all gears in the headstock, the apron and
on the teeth of the rack on the underside of the front
way.
Lathe Belts
The Logan Lathe is delivered equipped with a flat belt
10
of web and rubber composition connecting the cone
pulley on the lathe with the countershaft. A V Belt is
also furnished to connect the 2 step V groove motor
pulley with the 2 step flat face pulley on the countershaft. The life and efficiency of both these belts will
be increased by keeping them clean and free from oil
and by slipping them off the pulleys to release the
tension, if the lathe is to be unused for any considerable
length of time.
PULLEY SIDE
The use of a flat belt makes removal of the spindle
unnecessary when replacing or changing the belt providing an endless belt is not required. This arrangement
has two distinct advantages. First. the belt may be
changed quickly and easily with a minimum of effort.
for it may be laced, glued or hooked on the spindle,
a simple procedure when compared with the task of
removing the spindle and slipping an endless belt
over it. Second, there is no risk of losing the alignment
that has been accurately achieved at the factory through
the use of precision gauges. Because of the high grade
materials used and the accurate workmanship in
assembling the headstock, under ordinary circumstances
it need not be taken apart during the life of the lathe.
However, should you desire to remove the spindle,
you may do so, as was explained in the spindle
description.
FIGURE 13A-GLUED BELT
If the belt is to be glued, make allowance for overlap and taper the overlap at each end so that ends
will join as shown. See Figure 13A. Double belts
should be split and each part tapered. Full directions
are usually supplied with the glue; follow carefully.
..-----
-..-,-.--·-·
FIGURE 13B-BELT HOOK
The simplest and quickest method of fastening belt ends
is by means of wire hooks, as shown in Figure l3B
above. A number of different types are available
which are easily attached by forcing the ends of the
hooks through the belting and folding them over.
FIGURE 13-LACED BELT
Fastening the flat belt over the spindle pulley is a
simple matter and may be done in any one of the
following ways.
The V Belt supplied is a standard lf2 inch endless belt
which is easily slipped into place over both the two
step V motor pulley and the 2 step flat face countershaft pulley.
The belt, if laced, may be joined by either gut or
rawhide throngs as follows . When the belting has been
cut to the desired length, square the ends and punch
ten holes as shown in Figure 13. Start the lace through
holes A and B, pulling both ends through, working one
to the right and one to the left, as shown. Do not cross
one layer of lacing over another on the pulley side
and do not allow it to kink or turn or the belt will not
run smoothly. Fasten the ends as shown. If round gut
is used cut shallow trenches between the holes on the
pulley side and sink the gut in them.
Cutting Tools
There are a great variety of c~tting tools used on
a lathe; each shape being adapted to the work to be
done and the finish to be left on the metal. Basically,
however, all employ the same principle for all operate
with a tearing action. The cutting edge of the tool tears
a chip from the work and breaks it into separate sections as shown in Picture 14.
II
LATHE TOOL BIT SHAPES
Top and Side View
Top View
Working Position
Side View
Working Position
Grinding Angles
Back Rake Angle ______ __ _j 6 1/2 o
Front Clearance Angle .. 7 °
Side Rake Angle _____ ___ ___ _18 °
Side Clearance Angle .. .. 8°
Lip Angle
_____________ 64 °
Left
Hand
Turning
Tool
)
f8.3o"
Back Rax., Angle
_____ _16'12 °
Front Clearance Angle .. 7 °
Side Rake Angle __ _________ _18 o
Side Clearance Angle .... 8 °
Lip Angle ---------------- --------64 o
71
Back Rake Angle __________ 16 1 ~
Front Clearance Angle .. 7 °
Side Rake Angle _
_18 o
Side Clearance Angle .... 8 °
Lip Angle ·······-·-···
___ 64 °
Back Rake Angle __________ 16 1/2'
Front Clearance Angle .. 7 °
Side Rake Angle ----···- -·· _18 °
Side Clearance Angle .... 8 °
Lip Angle ······-···--------------64 '
11
~IS"
Round
Nose
Turning
Tool
.
Back Rake Angle __________ 16'12 o
Front Clearance Angle _ 7 °
Side Rake Angle --·--------·· o o
Side C'earance Angle ___ 8 °
Lipe AnJle --·------------------ 82 °
l
I
Threading
Tool
E
Back Rake Angle ____________ 0 °
Front Clearance Angle _ 5 o
Side Rake Angle _____________ 0°
Side Clearance Angle .. 10°
Lip Angle ----------------------- 80 °
)
Cut-Off
Tool "
1
t
0
Back Rake Angle ___________ 0 °
Front Clearance Angle _ 5 o
Side Rake Angle .. ________ o oSide Clearance Angle ... 3°
1?2
FIGURE 17
12
This angle directs a large portion of the cutting pressure
directly toward the base of the tool post.
When using the tool holder, the cutting end of the bit
should be clamped as close to the end of the holder as
possible and the bit holding end of the holder should
be as close to the tool post as possible. This will give
the cutting edge rigid support so that the action of the
work will not force it downward, causing chatter and
possibly breaking off the bit.
FIGURE 14-CUTTING ACTION OF TOOL BIT
Because of this the cutting edge of the tool must be
sharp enough to separate the chip from the work with
a minimum of power, but must also be large enough to
support the cutting surface and to carry the heat of
friction away from the point. These two opposiflg
requirements can be accomplished by carefully working out the angle at which the tool will enter the work
and the angles of clearance between the tool and the
work.
Holding the Work
There are five common methods of holding work in
a lathe; between centers, in a chuck, on the face plate,
in a collet, and on a mandrel.
SIDE RAKC.
ANGLE
MOUNTING BETWEEN CENTERS
Whenever possible the work is turned between centers
as this method is most accurate and permits removing
the work from the lathe and replacing it without affectling the accuracy.
(FRONT
CLEARANCE ANGl-E:
The first step in turning between centers 1s to f\nd the
center of the ends of the work and drill center holes.
This operation is important and should be done with
care.
C LEARANCE ANGLE:
FIGURE 15-CUTTING ANGLES
If square, hexagonal. or any other regular sided stock
is used lines may be scribed across the ends from
corner to corner, the point of intersection being the
center.
Figure 15 above illustrates a cross-section and a side
view of a tool bit in working position showing the
names of the various angles for grinding and setting
the bit.
For efficient performance, each of the angles and settings shown should be specially determined for the
particular kind of material being worked on, the material the tool bit is made from, the cuttmg speed, the
kind of coolant being used, if any, and whether roughing, finishing, parting or forming work is being done.
Figure 17 illustrates the seven bit shapes commonly
used and the working position of each with the correct
angles for an average cut in mild steel at a cutting
speed of 80 feet per minute using high speed tool steel
bits and machining without coolant.
8
0
0
In shaping the bits use a good medium grit grinding
wheel being careful not to burn the edges. Cool the
bit in water to prevent drawing the temper.
FIGURE 18-FINDING CENTERS
If round stock is used the center may be found either
with dividers or with hermaphrodite calipers. When
using dividers open them to approximately half the
diameter, and laying the stock on a flat surface place
one point on the work, the other on the flat surface, and
scribe a line along the end as shown in Fig. 18. Turn
the stock a quarter turn and scribe another line and
so on until the four lines are drawn as shown. If the
dividers are held at the same angle each time, the center
of the small square formed will be the center of the
stock.
FIGURE 16-TOOL HOLDER
A tool bit holder for holding 1/4- by 1/4-inch tool bits
eliminates the use of large and more expensive tools of
high speed steel and also holds the bit at an angle.
13
~
If hermaphrodite . calipers are used open them to approximately half the diameter of the stock and holding
the bent leg on four quarter points of the circumference,
scribe four arcs across the end, forming a four-sided
central figure. The center of this figure will be the
center of the stock. Rubbing chalk on the ends will
make the scribing more easily seen.
TAILSTOCK
When the center of the stock has been found, place a
center punch vertically on the center mark and strike
with a hammer, making an indentation sufficiently deep
so that the work will revolve on the center points of
the lathe.
The stock, especially if close to finish size, should be
placed in the lathe and the center tested before countersin~ing_. !his is done by revolving the stock by hand
~h1le 1t IS held between the centers and holding a
p1ece of chalk so that it will touch any high spots on
the work
FIGURE 21-MOUNTING BETWEEN CENTERS
will not turn evenly or smooth and will be inaccurate.
A correctly drilled and countersunk hole is shown in
Figure 22.
Lubricate the end centers by filling with heavy grease
or with white lead thinned with machine oil or light
cylinder oil.
If the chalk encounters high spots move the center holes
toward these high spots by placing the work in a
vise and driving the center punch toward them at an
angle, then bringing it back to a vertical position.
Place the end of the work in a lathe dog so that the
tail of the dog extends beyond the end of the work and
into the slot of the face plate, without interfering with
the headstock . center. The work should now rest firmly
on both centers but should not bind. To test the mounting, place a finger on the tail of the dog and move
it back and forth within the face plate slot. You should
be able to move it easily, but not too easily. When
the pressure on the ends has been adjusted lock the
tailpost ram by turning the binding lever to the right.
The countersink drill is usually used in drilling center
holes since it both drills the hole to the proper depth
and countersinks at the proper angle.
CHUCK
WORK
TAILSTOCK
CHUCKS
Two types of chuck commonly used are the 3-JA W
UNIVERSAL CHUCK and the 4-JAW INDEPENDENT
CHUCK. These are used in turning the work that can
not be readily turned between centers. See Figure 23.
FIGURE 20-COUNTERSINKING CENTERS
The countersink drill is mounted in a chuck in the
headstock spindle and the work held with the tailstock
center in one center hole, the drill in the other. With
the spindle turning at about 600 R.P.M. the tailstock
ram is then advanced moving the work into the drill
as shown in Figure 20.
If this method is not used the center holes may be
drilled by placing the work in a drill press, or the
work may be held in a universal three-jaw scroll chuck
and the countersink drill held in the tailstock in a drill
chuck. When this method is used the end of the shaft
should be faced smooth before drilling the center hole
When drilled and countersunk the holes should be deep
enough to prevent the points of the lathe center touching the bottom, and the tapered sides should exactly fit
the 60 ° anqle of the centers. If they do not the work
FIGURE 22-3 AND 4 JAW CHUCKS
14
Some chucks mount directly on to the spindle nose, while
others are bolted to an adapter plate which fits on to
the spindle.
Before mounting a chuck or face plate clean the
spindle shoulder and chuck back and oil the threads of
the spindle head and chuck thoroughly. oTurn the
:huck on by hand, being careful not to spin it up to
the shoulder as it may jam. Never use lathe power to
screw a chuck on or off of the spindle.
A
The chuck can be loosened for removal by (1) Engaging
the back gears while the bull gear is connected to
the spindle pulley, so that the spindle will not turn, and
turning the chuck by placing the chuck wrench in its
hole and pulling on it. (2) Placing a block of wood between the chuck jaw and the lathe bed, engaging the
back gears, and turning the spindle by pulling by hand
on the belt. Take care in removing the chuck. You may
damage the spindle threads or you may damage the
bed ways if the chuck falls on them.
B
FIGURE 23-LATHE CHUCKS
THE CENTER REST CHUCK (Fig. 23B) is mounted in
the tailstock by means of a solid tapered arbor which
replaces the center. The stationary bronze jaws provide
an accurate support for turning round work where a
center cannot be used.
The 4-jaw independent chuck is recommended if the
lathe is to have only one chuck as it will hold square,
round or irregular shaped work in either a concentric
or eccentric position. Each jaw is controlled by a head
screw, a number of concentric circles scribed on the
face permitting the approximate centering of the work
by moving all jaws to :he same line or to the same
distance from. the same line.
,
E
[)
The work is then revolved by hand and a piece of
chalk held lightly against the work to mark the high
spots. The jaw opposite the high point is loosened and
that behind it tightened until the work is centered.
"~~
B
. ~ -_.'" '"~ ·::.. ·.i '-.i ·::. ·:.o;:.c.<~<~y·':c.· -;:_
The 3-jaw universal chuck is self-centering, all jaws
working from one screw which saves time and trouble
in centering round or hexagonal work but it can not
be used for square or irregular shapes.
lJ
r
B
c
LATHE HEADSTOCK SPINDLE
FIGURE 24 -DRAW-IN COLLET ATTACHMENT
DRAW-IN COLLET CHUCK. Small work that must be
very accurate is mounted in a draw-in collet placed
within the headstock spindle.
The 4-jaw chuck can be adjusted to any degree of
accuracy required. 3-jaw chucks are usually accurate to
.003 when new. If greater accuracy than this is re·
quired, the jaws may be shimmed as needed.
The assembly consists of a draw-in spindle (A in Fig.
25) threaded at the right end to receive the collet; a
tapered closing sleeve (B); a split holding collet (C);
spindle nose cap (D); and spindle nose cap wrench (E).
The tapered closing sleeve fits into the headstock spindle
and adapts it to the collet. The work is placed in the
split end of the collet and the collet closed by pressure
as it is drawn into the taper by the draw-in spindle
which enters the headstock spindle from the other end.
The jaws of the 4-jaw chuck are reversible, while an
additional set of jaws are supplied with the 3-jaw chuck
for internal chucking in which case the jaws are placed
inside the work and the outside turned.
Never use a collet for work more than .005 inch larger
or smaller than its rated diameter. Before mounting ·work
in a collet, all parts-work, collet, spindle, and tapermust be wiped clean and dry.
DRILL CHUCKS (Fig. 23A) are used both on the tailstock
of a lathe with the work turning and on the headstock
of the lathe with the work held. Although for production
drilling, a drill press is generally used, there are many
small jobs of drilling, reaming, tapping, etc., that
are conveniently handled by means of a lathe drill
chuck.
When removing the collet assembly unscrew the draw-in
spindle a couple of turns and press the collet loose. To
remove the tapered closing sleeve, unscrew the spindle
nose cap with spanner wrench which forces the sleeve
out of the lathe spindle.
15
FIGURE 27-FACE PLATE
FIGURE 28-MANDREL
FACE PLATE MOUNTING
outer surface to be turned instead of the limited surfac+
that would be available if the piece were held in a
chuck.
Many irregular shapes are best mounted for turning by
clamping to the face plate directly or by fastening to
an angle plate which in turn is mounted on the face
plate. (Fig. 27) Be careful in bolting down not to spring
the work on the plate and use the same care in screwing
the face plate on the lathe spindle as described for
mounting chucks. Heavy work mounted off center
should be counterbalanced by attaching balancing
weights to the opposite edge of the face plate. To locate
the work accurately on the face plate use either a dial
indicator or a center indicator.
Although mandrels are available which may be expanded to fit the .-..ole by forcing out grips on the sides,
a mandrel is usually a piece of steel with a slight taper
(.006 inches per foot) the ends flattened for the lathe
dog and the piece held to the mandrel by friction. When
mounting the work it is advisable to oil both the mandrel
and the hole to prevent the work "freezing" on the
mandrel. In driving the mandrel out of the work do not
use a steel hammer without protecting the end of the
mandrel from damage. Make sure that mandrel is
driven off in the opposite direction than that from which
it entered the work.
MANDREL MOUNTING
Hollow pieces may be mounted on a mandrel and the
mandrel mounted between centers, allowing the entire
Fig. 29 Motor and Switch Wiring Diagram
i,.l
Terminal lo•
Switch Boll
Te1 minol Box
T2
f
yc2
Cl
!rJ
T4!
yr1-2
Leo
Cl
czy
!n-4
I
No. 1105 Motor
(Capacitor type)
lf:z H.P. 230 volt; .
60 cycle, single
phase
No. 0639 Switch
No. 1105 Motor
(Capacitor type)
lf2 H.P. 115 volt,
60 cycle, single
phase
No. 0639 Switch
(R-1144)
(R-1144)
T3
yTSny
Tl
Tfa
T 2
L.~
Cl
I I
Til
Tl
. ..
Switch lox
Terminal lox
T7
T41
Tl
Cl
L.Z
L2
F4
Tl
C2
L.l<>
0
T4r
TZ
I I
Ll
Switch ...
iT
L.l<>
1·7
o-Ll
T2·11!
tr,.~
L2y
Ll
rT"J
..........
Te,minol lox
No. 1110 Motor
Vz H.P. 220 volt,
60 cycle, three
phase
No. 0636 Switch
No. 1110 Motor
lf:z H.P. 440 volt,
60 cycle, three
phase
No. 0636 Switch
(R-1143)
(R-1143)
T7
lTI
Til
Til
Tlz
T~
r- f-oTI
Llo
~
TJ
T3
L2y
J 11
Ll3
3
LZ
Ll
Ll
Switch lox
Switch ...
T..-mtnol lo•
. T7 ,
Tl
T II
T 2
T9
T3
No. 1111 Mote::
% H.P. 220 volt,
60 cycle, three
phase
No. 0636 Switch
No. 1115 Motor
(Capacitor type)
3/4 H.P. 115 volt,
60 cycle, single
phase
No. 0639 Switch
<R-1144)
(R-1143)
A,.,
Cll
~,..
cz
cr.
lr.
T'f
1..2"'
Cll
1..1
y
I I
L2
1..1
1..&
Ll
3-I -52-2M
16
PR
LITHO IN U.S.A.
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