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PM-727MV v6 2020-10
Copyright © 2020 Quality Machine Tools, LLC
Figure 4-5 X-axis backlash adjustment
Figure 4-6 Y-axis backlash adjustment
DOWNFEED RETURN SPRING TENSION
The quill should automatically retract when the coarse
downfeed levers are released following a drilling opera-
tion. If not, the return spring may need to be re-tensioned
– but rst check for other issues such as obstructions or
lack of lubrication.
A pin in the headstock casting engages in one of 6
notches on the rim of the cup-shaped spring housing.
Spring tension is adjusted by disengaging the housing,
see below, then rotating and re-engaging it at the de-
sired tension – clockwise to reduce, counter-clockwise
to increase.
To adjust the tension:
1. Wear heavy-duty leather gloves for hand protection
2. Loosen one half turn, but do not remove, the knob
holding the spring housing in place.
3. While holding the housing rmly to stop rotation,
continue to loosen the knob to the point where the
housing can just be disengaged from the pin.
4. Step the housing round to the next notch, then tight-
en the knob to secure the housing. Test for tension.
5. Repeat as necessary, then fully tighten the knob.
Take extra care when working on the spring — it
can unwind violently if not controlled
Figure 4-7 Return spring housing
Notches in the rim, arrowed, allow 6 radial settings
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