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Copyright © 2020 Quality Machine Tools, LLC
PM-1440GS v3 2020-10
Figure 3-13
External gear set F
To change gear sets loosen the 17
mm nut, arrowed, then swing down the support casting (quadrant).
SADDLE FEED GEARBOX
Stop the motor before changing feed direction or rate
The saddle feed can be to the left, right, or disengaged, as se-
lected by the Saddle Feed Direction lever on the main control
panel, Figure 3-1.
TAILSTOCK
The tailstock leadscrew has a 10 TPI thread, with 4 inch travel.
A graduated collar on the tailstock handwheel reads 0.001”/
division. To remove tooling from the tailstock taper (MT4) turn
the handwheel counter-clockwise (handle end view) until re
-
sistance is felt, then turn the handle a little more to eject the
tool. Conversely, to install a taper tool make certain that the
quill is out far enough to allow firm seating.
For taper turning the tailstock may be offset by adjusting set
screws on either side, Figure 3-11. To move the tailstock to
the front, for instance, the screw on the lever side would be
unscrewed, then the opposing set screw would be screwed in
to move the upper assembly.
A visual indication of the offset is provided by a scale on the
back surface, but this is not a reliable measure for precise
work. In practice, the only way to determine the offset precisely
is to "cut and try' on the workpiece, or scrap stock, homing in
on the correct degree of offset in small increments.
The same issues arise when re-establishing "true zero" of the
tailstock, in other words returning it to the normal axis for rou-
tine operations. One way to avoid cut-and-try is to prepare in
advance a bar of (say) 1" diameter quality ground stock, with
precise center drillings
at both ends (do this by indicating for
zero TIR in a 4-jaw chuck, not in a 3-jaw unless known to be
predictably accurate). The prepared bar can then be installed
between centers and indicated along its length.
Figure 3-11
Tailstock
Offset scale
Offset adjust
Offset
adjust
Figure 3-12
Saddle feed gearbox controls
The rate of power feed relative to spindle speed is set by the
four shifter knobs below the main control panel, Figure 3-12.
The
W-X-Y
knob at right determines which is the driven shaft,
leadscrew (
W
and
Y
) or feed shaft (
X
).
Select W to cut U.S. threads (TPI), Y for metric threads
A distinctive feature of the PM-1440GS is its ability to cut a
wide range of U.S. and metric threads with only two external
gear sets, Figures 3-13 and 3-17.
