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OTMT SC4 User Manual And Installation Manual page 39

Bench lathe
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various sizes of gears. In addition, the B-C
shaft can be moved in or out along the arm of
the frame.
In order to fit the gears onto the B-C shaft, it
may be necessary to loosen the shaft by
turning the square end counter-clockwise and
then slide the B-C shaft further out along the
support arm; then retighten the shaft. It may
also be necessary to install the gears in a
particular sequence so that one gear does not
overlap and block the position of another gear.
When new, the gears may fit very tightly on the
shafts. To remove the gears it may be
necessary to use a pair of long screwdrivers to
prise the gears gently off of the shaft. When
removing the nuts that secure the gears to the
shafts, use one hand to hold the spacing
washers; they are slotted and will drop off of
the shaft when the nut is loosened.
When all four gears have been secured by the
washers, nuts and the bolt for the D shaft,
loosen the square end of the B-C shaft and
slide the B and C gears along the support arm
until the C gear meshes with the D gear.
Tighten the square end of the shaft. Next,
loosen the 14mm bolt on the cutout arc below
the D shaft and rotate the entire gear train
clockwise until the B gear meshes with the A
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gear. After meshing the gears, tighten the
14mm bolt.
Rotate the lathe chuck by hand to make sure
that gears are properly meshed and turn
without interference. There should be a small
amount of play, or free space, between the
teeth of the meshed gears to keep the gear
train from binding.
Gear trains for cutting metric threads are set
up the same way but using a chart that shows
the pitch of the thread in millimeters
Gear Trains for Metric Threads
Power feed gear trains also are set up the
same way except that a lower gear ratio is
used so that the rotational speed of the
leadscrew is much lower than for threading.
Power Feed gear trains