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PM-236 v4 -207.indd
ENGAGING THE POWER FEED
Power feed controls are located on the apron, Figure
3-4. The split-nut lever engages the leadscrew, and is
typically used only for thread cutting (S-M knob on gear
box set to M), described later.
The power feed lever is active only when the
feed shaft
is rotating, S-M knob on gear box set to S. In its neutral
position the lever tip is captive between two offset stop
blocks. This prevents vertical movement of the lever un-
less it is first shifted to the left or right — a safety mea-
sure to avoid accidental engagement of the power feed.
Figure 3-4
Power feed levers on the apron
FEEDSHAFT CLUTCH
The clutch shown in Figure 3-5 disengages the power
feed if the carriage or cross slide hits an obstruction
when power feeding, thus minimizing the potential for
damage. This could be the result of either an accidental
event, or deliberately stopping the carriage at a precise
location set by the stop, Figure 3-6.
The clutch comprises a pair of spring loaded steel balls
bearing on a detent disc driven by the carriage feed
Figure 3-6
Micrometer carriage stop
Figure 3-5
Feedshaft clutch
gearbox. Spring pressure is adjusted by two set screws
on either side of the feed shaft, arrowed in Figure 3-5.
Setting the spring pressure is a process of aiming for the
best compromise between too high — damaging feed
pressure — and too low, which might mean unexpected
stopping for no good reason. Setting the clutch to work
reliably with the micrometer carriage stop is a good ex-
ample of such a compromise: start with low spring force,
then work up in small increments until the carriage stops
in the same location (say ± 0.002”, assuming a constant
depth of cut and feed rate).
CARRIAGE STOP
The stop asembly, Figure 3-6, has a micrometer-style
collar graduated in 0.00 in. divisions. It can be clamped
at any point along the lathe bed (two M6 socket head
screws on the underside secure the clamp plate to the
block). Make certain that the stop rod seats firmly on the
carriage casting, not on the rubber wiper.
Carriage feed — lever
left & up
Cross slide feed — lever
right & down
When engaging either power feed,
move the lever gen-
tly
, feeling for the gears to mesh as you go. If the gears
don’t engage at the first try, use the appropriate hand-
wheel to jiggle the carriage or cross slide, whichever one
you wish to move under power.