quick change gearbox
Gearboxes supplied for
subsequent fitting only Far M
L7 lathes prior to K125240 and
Super 7 lathes prior to
SK124461 instead of screws
267 (paragraphs 9, 11S and
11M also parts list) use 1/2"
B.S.F. x 3/4". If far your
machine you need the 1/4"
B.S.F. screws, return the metric
screws to us for exchange.
No. 712V
QUICK CHANGE
GEARBOX
Nos, 1480 (ML7) and 1680 (ML7-R) and Super 7)
INSTRUCTIONS FOR
INSTALLATION AND OPERATION
WITH
PICTORIAL PARTS LIST
Myford Ltd, Wilmot Lane, Chilwell Road, Beeston, Nottingham NG9 I
ER Telephone: 01 15 925 4222 • Fax: 01 15 943 1299 email address:
Myford@btinternet.com
MYFORD QUICK CHANGE GEARBOX
CAUTION
IT IS OF THE UTMOST IMPORTANCE THAT THE WHOLE
GEARBOX AND TRANSMISSION MECHANISM SHALL ROTATE
WITH COMPLETE FREEDOM.
MYFORD QUICK CHANGE
G A O
OPERATION
The Myford Quick Change Gear Box permits instant
selection of 48 English threads and feeds without the necessity for
setting-up gear trains. A conversion set is available for cutting
Metric, B.A., and thousands of other odd pitches, using ordinary
changewheels in conjunction with the gear box.
MISALIGNMENT OF LEADSCREW OR TIGHTNESS IN ANY OF
THE BEARINGS (GEAR TRAIN-GEARBOX-OR LEADSCREW) WILL
IMPOSE HEAVY LOADS ON THE GEAR TRAIN AND MAY LEAD TO
SERIOUS DAMAGE.
THE CUTTING OF UNUSUALLY COARSE PITCHES IN EXCESS
OF .125"), EXERTS EXCESSIVE PRESSURE ON THE LEADSCREW
AND GEAR MECHANISMS. GREAT CARE SHOULD BE TAKEN SO
AS TO MINIMISE THE LOADS IMPOSED.
N.B. When changing to the slotted quadrant (page 6 fig. 5) or
back to the standard quadrant (page 3 fig. 2) it may be
necessary to reset the anchor pin No. 03 (see page 15
paragraph 22) in order to line up the driven gear on the
first stud with the driver on the tumbler stud.
The chart for diametral pitches has been included for the
benefit of users wishing to cut worms to mesh with
wormwheels whose pitch is expressed as D.P. The table of
module pitches has been included for the same reason.
Wh ere as diametral pitch is the ratio of the number of teeth
to the pitch diameter (in inches), module is the ratio of the
pitch diameter (in millimetres) to the number of teeth.
Fig. 1. Gear Box Chart showing English threads and feeds.
Reference to the gear box chart Fig. 1, will show that all
the commonly used English pitches are covered. In view
of this the gear pins on the normal quadrant (as supplied
with the gear box), are placed at fixed centres. This permits
the advantage of mounting the driving train of gears on pins
which are considerably greater in diameter, and more robust
than the movable type of changewheel stud.
LUBRICATION
Before operating the lathe, remove the level plug
(at the right-hand end of the boxy, and fill to
just short of plug level with 80025, Esso Febis
K68 oil. Replenish the oil bath occasionally. At
long intervals, flush with 800127, Esso Nuto
The tumbler reverse gear pins and quadrant gear
pins should be lubricated frequently. Occasional
application of the oil gun to the oil nipples on the
gear box will be sufficient.
Fig. 2. Normal
Illustrations not binding in detail.
3
SET UP No 1
SET UP No 2
Fig. 3. Chart showing Changewheel Trains for Diametral Threads. (The four diagrams on
pages 4 and 5 apply to Diametral, Module and B.A. Charts).
3
Fig. 4. Chart showing Changewheel Trains for Module and B.A. Threads. (The
four diagrams on pages 4 and 5 apply to Diametral, Module and B.A. Charts).
5
MYFORD QUICK CHANGE GEARBOX
MYFORD QUICK CHANGE GEARBOX
METRIC, B.A., AND ODD THREADS AND PITCHES Hundreds
of odd threads, metric threads and feeds can be obtained by
using a special slotted quadrant, with standard changewheels
on movable studs, in place of the normal quadrant and gear
train as supplied with the gear box. (See also pages 4 and
5).
CONTROLS
The Myford gear box is designed for smooth and easy
operation. To obtain the various threads and feeds it is only
necessary to arrange the levers of the gear box and the
reversible cluster gear, as indicated on the Chart (6) Fig, 7.
IMPORTANT
The movement of the control levers whilst the lathe is
in motion is only practicable when set for fine feeds.
The lathe speed must be slow and the load light.
Generally it is preferable to stop the lathe and turn
the spindle by hand whilst engaging the gears.
DO NOT USE FORCE.
Fig. S.
Slatted Quadrant (with movable changewheel studs "exploded" to
show construction).
THE METRIC CONVERSION SET (No. 14811, not 1481)
comprises a slotted quadrant, 12 changewheels, 2 spacers, and 2
movable changewheel studs. This set covers all the pitches shown on
the METRIC CHART which is located inside the hinged gear guard.
Alternatively, the slotted quadrant can be supplied separately, or
with any changewheels, spacers and movable studs which are required
for a particular gear train.
Fig. 6. Metric Chart (located inside the hinged gear guard).
6
Care should be taken when No. 1031 MYFORD
spindle nose collets are being used, or when any
other work is being done close to the headstock
spindle nose. Under these conditions the leadscrew
guard and clasp nut lever are both very close to the
gearbox, and serious damage would ensue if the
leadscrew guard were allowed to run into the gearbox.
Fig_ 7.
Quick Change Gear Box Controls. 7
MYFORD QUICK CHANGE GEARBOX
The SELECTOR (1) selects any one of the eight ratios available
from the 'cone' of gears on the lower shaft. The indexing position
of the lever is always directly below the column on the chart which
contains the thread or feed desired. (See Fig. 7).
To move the Selector it is necessary to pull the knob forward
the slide provided underneath
the desired position.
The LEVER (2) provides three variations of the ratio selected by
and lift the lever until it bears against
the cover plate, then slide sideways to
the selector (1). The position of the lever (2) is indicated on the
chart to the left of the line which contains the thread or feed
desired.
The REVERSIBLE CLUSTER GEAR (3) is changed (i.e. the
Cluster Gear is mounted with the 57T or larger gear innermost) to
select the range of fine pitches. (See Figs. 8, 9 and 1D).
Reversal of Cluster Gear (3) is permitted by the Swinging
Latch which retains the Cluster Gear.
NOTE:
The TUMBLER REVERSE LEVER (4) must be set to the neutral
position, to allow easy meshing of the Cluster Gear with the adjacent
gears on the quadrant.
The QUADRANT CLAMP (5) permits adjustment of the
alignment of the quadrant gears with the WHEEL ON THE TUMBLER
CLUSTER.
MYFORD QUICK CHANGE GEARBOX
INSTALLATION
The MYFORD Quick Change Gear Box can be easily fitted to
the Lathe if the following instructions are carried out.
The Quick Change Lathe r e q u i r e s a shorter leadscrew than
standard, and whilst this item is available, it is practicable to
shorten the existing leadscrew. The leadscrew guard must also be
shortened on ML.7 machines.
During the past years minor modifications have been carried
out on ML.7 Lathes, for example, the latest changewheel guard
backplate can be removed without disturbing the tumbler reverse
assembly. All except the earliest machines (both ML.7 and Super
7) have been drilled and tapped ready to accept the gearbox.
The part numbers referred to in the FITTING INSTRUCTIONS
are those used in the PICTORIAL PARTS LIST.
IMPORTANT. It is essential that the following instructions are
carefully adhered to, and in particular that the GEARBOX AND
TRANSMISSION MECHANISM SHALL ROTATE WITH COMPLETE
FREEDOM.
MISALIGNMENT OF LEADSCREW OR TIGHTNESS IN ANY OF
THE BEARINGS (GEAR TRAIN-GEARBOX-OR LEADSCREW) WILL
IMPOSE HEAVY LOADS ON THE GEAR TRAIN AND MAY LEAD TO
SERIOUS DAMAGE.
After assembly, and before operating under power, the
required freedom should be ascertained in the following manner:(1)
(2)
Disengage tumbler reverse.
Set reversible cluster, 3 Fig. 7, in screwcutting position,
i.e. with smaller gear (19 teeth) innermost.
(3) Set lever, 2 Fig. 7, on top of box, in a position giving
disengagement of gearing.
(4) Set selector, 1 Fig. 7, in 8 T.P.I.
position.
Disengage lead screw nut (clasp nut lever in upper
position).
(A) Gripping on the 8 T.P.I. threaded portion
possible to rotate the leadscrew.
FIG. t
o 8
it should be
Gripping the 72 tooth wide input gear it should be
possible to rotate the input drive gearing and the gears in
the box.
9
MYFORD QUICK CHANGE GEARBOX
OPERATION OF LEADSCREW NUT, ETC.
ML.7, ML.7-R and SUPER 7 Lathes are fitted with a stop screw to the
leadscrew nut to control the depth of engagement with the leadscrew, and if
your Lathe is not arranged with this feature it
is recommended that you carry out the modifications as shown at Fig. 11
below.
The screw should be so adjusted that there is minimal backlash
between leadscrew and nut but without causing any binding.
Furthermore, we recommend that when the gear box has been Fitted
and lined up, the right hand leadscrew bracket should be dowelled to the
Lathe bed. Please see Fig. 12 below,
MYFORD QUICK CHANGE GEARBOX
FITTING INSTRUCTIONS Where paragraph numbers are duplicated, The letter
S denotes Super 7 and the letter M denotes ML.7 except as shown below.
For ML.7 Lathe serial number K1087186 and higher numbers ignore ML.7
instructions and treat as though Super 7, e.g. paragraphs 1. 2, 3, 4S, SS etc.
For ML7-R lathe, treat as though later ML7 lathe (K108718B) and higher
numbers, i.e. paragraphs 1, 2, 3, 45. 5S etc.
For Super 7 Lathe SK108891B and higher numbers, packing strip
reference 230 is no longer required and must not be used.
For Super 7 Lathes fitted power cross traverse (SK115830 and higher
numbers) treat as though ML-7. e.g. paragraphs 1, 2, 3, 4M, 5M etc.
Preparing the Lathe
See notes in heading
45 With the carriage adjacent to the
right-hand leadscrew bracket, engage
the clasp nut to support the leadscrew,
and tighten the clamp bolt at the rear of
the saddle. Fig. 14.
FIG. 13
Fig. 11. Diagram showing stop screw and spring fitted to leadscrew nut.
1 Open changewheel guard. Remove
the changewheel quadrant and change
wheel guard backplate.
Note On earlier ML.7 models it will be
necessary to remove the tumbler
reverse assembly to facilitate backplate
removal.
2 Fit the 24T gear to the tumbler sleeve
gear. Fig. 13.
i
Note A 24T gear in high tensile steel s
provided with each gearbox.
3 Remove the tailstock from the machine
FIG. 15
5S Remove the Simmonds nut, leadscrew handwheel and driving pin from
the leadscrew. Release the caphead
screws which secure the leadscrew
bracket, and remove the bracket.
Fig. 15.
6S Disengage the clasp nut and withdraw the leadscrew to the right.
7S Remove the left-hand leadscrew
bracket.
See notes in heading
4M With the carriage near the headstock
end of the bed engage the clasp nut to
support the leadscrew and tighten the
clamp bolt at the rear of the saddle.
Fig- 14, but saddle at other end of
bed.
5M Remove left-hand leadscrew bracket.
Fig. 12. Diagram showing dowelling of leadscrew
bracket.
14
FIG. 14
6M Remove the leadscrew guard and
shorten to the new dimensions given in
Fig. 16.
MYFORD QUICK CHANGE GEARBOX
MYFORD QUICK CHANGE GEARBOX
Remove the right-hand leadscrew
bracket assembly, leadscrew gear and
leadscrew, and rut off surplus and trim
the leadscrew end.
Remove the template and replace the
headstock thrust screws.
Preparing the Gearbox Attachment
Holes. (ML.7 and Super 7).
8 Where attachment holes for the
gearbox are NOT already provided in
the Lathe bed. withdraw both headstock
thrust screws to permit the mounting of
the drilling template No, 232, Fig. 17.
{Available on request, if required.)
Note It is important that the drilling
depth indicated should not be exceeded.
15S With the carriage in the central
position enter the leadscrew through
the clasp nut from the right-hand
side and engage the clasp nut.
10 Remove from the gearbox. the top
cover No. 260, 72T wide faced gear No.
186, and the gear quadrant No. 202
complete with gears. Fig. 20.
9 Mount the template using two 1/4"
FIG. 21
FIG. 17
FIG- 16
strip No. 23D must be inserted before
fitting the caphead screws No. 267,
but
not
for
SK108891 B and
onwards). 12S With the carriage in a
central position, enter the leadscrew
through the clasp nut from the righthand end, and engage the clasp nut.
Traverse the carriage to the left until
the leadscrew passes right through
the Gearbox bearings Fig. 21.
13S Assemble
the
right-hand
leadscrew bracket on the leadscrew,
and lightly tighten the securing screws.
Open the clasp nut, traverse the
carriage to the right-hand end,
engage the clasp nut to centralise the
leadscrew, and secure the leadscrew
bracket.
Replace the driving pin, handwheel, and
Simmonds nut, to locate the leadscrew
See notes in heading, page 11
11S Mount the gearbox using the two
caphead screws No. 267 provided,
Ensure that the rubber sealing washer is
correctly positioned in the recess before
tightening the captive screw. See diagram Fig. 18. At this stage all three
screws
should
only
be
lightly
tightened. (Note For SUPER 7 Lathe, the
packing
B.S.F. x 3/8" long caphead screws and
drill the two mounting holes for
gearbox. Fig. 19,
Remove the template and open out
the two drilling guide holes in it to 1/4"
dia. Remount the template as a tap
guide, and tap the two gearbox
mounting holes 1/4" B.S.F., as shown in
the diagram.
FIG. 19
FIG- 20
1
14S Position the leadscrew gear No. 168
to give 015" clearance from the
Gearbox face and note the amount of
surplus to he removed from the leadscrew to provide .031" maximum
projection through the leadscrew
gear. See Fig- 22.
16S Re-assemble the leadscrew and
right-hand leadscrew bracket assembly.
Centralise and finally secure the
bracket. Check the leadscrew for free
rotation. (Upper lever in neutral
position).
See notes In heading, page f1
11114 Feed the gearbox on to the
leadscrew and mount the box using the
two
caphead
screws
No.
267
provided. Ensure that the rubber sealing
washer is correctly positioned in the
recess before tightening the captive
screw. See diagram Fig. 18. At this
stage the 3 screws need only to be
lightly tightened. 12M Position the
leadscrew gear No. 168 to give 015'
clearance from the gearbox face and
note the amount of surplus to be
removed from the leadscrew to provide
-031" maximum projection through the
leadscrew gear. See Fig. 22.
13M Remove the gear No. 168 and
detach the gearbox.
14M Remove the Simmonds nut,
distance
collar
(or
leadscrew
handwheel, if fitted) and driving pin
from the leadscrew. Release the socket
set screw which secures the collar on
the leadscrew to the left of the bracket.
15M Disengage the clasp nut and
withdraw the leadscrew to the left. Cut
off surplus and trim the leadscrew end.
FIG. 22
MYFORD QUICK CHANGE GEARBOX
MYFORD QUICK CHANGE GEARBOX
20 Assemble the leadscrew gear. with
driving pins or Woodruff key. onto the
leadscrew end. position to give .015"
clearance from the gearbox face and
secure with the grubscrew. See Fig. 22.
Final Assembly
FIG. 23
16M Fit the leadscrew back into the
machine. feeding it through the clasp
nut and replacing the collar (to the left
of the bracket) before passing through
the right-hand bracket.
17M Mount the gearbox back into
position ensuring that the rubber
sealing washer is correctly positioned
in the recess before tightening the
captive screw. At this stage all 3 screws
should only be lightly tightened. Replace
the shortened leadscrew guard on the
apron.
Aligning the gearbox
19 The gearbox bearing should now be
Centralised with the leadscrew, and at
the same time levelled (i.e. set parallel
with the top surface of the Lathe ways).
Adjustment of the position of the box.
before final tightening, is accomplished
by inserting wooden wedges under each
end of the box, alternatively jack
screws can be used. Levelling can
either be carried out with a dial gauge
as shown in diagram Fig. 23 or with an
accurate spirit level (check in relation to
top surface of bed ways). Misalignment
in the vertical plane will be shown by
vertical deflection of the leadscrew.
when the clasp nut is operated.
IBM Replace the driving pin, distance
collar (or leadscrew handwheel, if
fitted). and Simmonds nut. Tighten the
Simmonds nut to position the collar to
the left of the bracket and tighten the
socket set screw to secure the collar.
Release the Simmonds nut and adjust
to allow the leadscrew to rotate without
end play
Finally tighten the three gearbox
securing screws, check the leadscrew
for free rotation and replace top cover
No. 260. (SET THE UPPER LEVER No.
197 TO A NEUTRAL POSITION WHILST
CHECK IS CARRIED OUT).
FIG. 24
FIG. 25
21 Drive the 1/4" B.S.F. Stud No. 220
into the lower of the three tapped
holes at the end of the lathe bed. and
screw an one each of the lock nuts and
washers No- 222 and 221 (nut first).
Attach the new change wheel guard
assembly to the machined end face of
the gearbox and cover No. 260 using
in the upper hole. the 2 B.A. cap
screw and washer Nos. 219 and 255; in
the lower hole. the hexagon head
screw and washer Nos. 217 and 221.
Screw the remaining nut and washer
Nos. 222 and 221 (washer first) on to
the stud. No. 220. and adjust the
locknuts to secure the guard backplate
without distortion
22 Place one of the two 3/8" dia.
washers on the anchor pin No. 203.
Assemble the gear quadrant No. 202
on to the input shaft housing No. 179.
and over the anchor pin. Lightly secure
the gear quadrant to the anchor pin
with the remaining 3/8" dia. washer and
3/8" B.5-F. nut- Fig. 24 Release the
grubscrew No. 195 which secures the
anchor pin in the gearbox and position
the gear quadrant to align the quadrant
gears with the 24T. CHANGE WHEEL on
the tumbler reverse stud. Secure the
anchor pin in this position. and tighten
the 3/8" B.S.F. nut.
and mount the wide faced 72T. gear on
the end of the input shaft. and secure
with 3/8" B.S.F. nut and washer. Fig.
(Note: this gear is keyed with the No.
404 Woodruff key which is supplied).
24 Set
the
various
controls
as
described on page 9 and check for
freedom of leadscrew and gearing as at
A and 3 at foot of same page.
25 Replace the reversible cluster gear in
the position which gives the fine pitch
range (i.e. with the 19T- gear
outermost). and test for free rotation
right through by manual rotation of the
headstock spindle- Fig. 26.
26
Before
operating
the
Lathe.
remove the level plug fat the right-hand
end of the box) and fill to over-flowing
with S.A.E. No. 30 oil. The tumbler
reverse gear pins and quadrant gear
pins should be lubricated frequently_
Occasional application of the oil gun to
the oil nipples on the gear box will be
sufficient.
23 Tighten the gear quadrant pinch
screw No. 139 (the pinch screw must
not be excessively tightened, as this
can cause stiffness on the input shaft
No. 183).
8
MYFORD QUICK CHANGE GEARBOX
INSTRUCTIONS FOR ORDERING REPLACEMENT PARTS
The following information should be supplied with the order:1.
Type and serial number of the lathe, also the serial number
of the gearbox.
For location of numbers see Figs. 27 and 28.
2.
Part number and name of part as shown on the preceding
list.
3.
Quantity Required.
As it is the Company's policy to improve its products whenever opportunity
occurs, designs are liable to modification at any time. In some cases. due to
the nature of the part will be necessary for us to supply additional related
parts. particularly if the item required has been altered.
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