Advertisement
Mills with power downfeed
Note: Use the graduated dial on the fine control hand-
wheel for guidance only. It has 20 divisions of approxi-
mately 0.002". Use the DRO for precise downfeed con-
trol. On power feed versions the quill is locked by the
lever on the left of the headstock, Figure 3-2.
Figure 3-2 Quill locking lever (power feed version)
USING THE POWER DOWNFEED SYSTEM
Stop the spindle before touching the Power
Feed Engage or Feed Rate Selector knobs.
Key points to remember, referring to Figure 3-0:
•
The Feed Rate selector knob can be turned either
clockwise or counter-clockwise to the OFF setting, but
not beyond — go back the other way instead.
•
The graduated depth collar is free to rotate on the
downfeed lever hub only when the depth collar clamp
lever is loose.
•
When the depth collar clamp lever is tightened, the
collar is driven by the lever hub.
•
The downfeed lever hub is full-time connected to the
quill pinion.
•
Pivot the quill downfeed levers inward to control the
quill by hand, drill-press style.
•
Pivot the levers outward to move the lever hub under
power.
•
The lever hub automatically disengages from the pow-
er feed — levers pivot inward — when the zero line
(0) on the depth collar nears the scale datum. At this
point the quill will reverse ABRUPTLY by spring
action unless restrained by light finger pressure
on one of the levers.
PM-940M 0-206 v.indd
(continued)
Power downfeed example
In Figure 3-3 a previously drilled hole is to be enlarged
using a single point boring tool. What follows is one of
several possible procedures.
Figure 3- Hole boring with power downfeed
.
With the quill fully retracted (), lower the headstock
to bring the cutting tool just clear of the upper sur-
face of the workpiece.
2.
Lock the Z-axis, Figure 3-4.
3.
With the cutting tool inboard of the drilled hole, lower
the quill by hand to the desired end point for the tool
(2).
4.
Lock the quill, then set the depth collar to zero.
5.
Tighten the depth collar clamp lever.
6.
Release the quill locking lever, allowing the quill to
retract fully, position ().
7.
Spindle stopped?
Power Feed Engage knob to ON. Jiggle the spin-
dle and Fine Control by hand to ensure the power
feed is properly engaged.
8.
Stay clear of the Fine Control knob — this will
rotate when the spindle runs.
9.
Turn the spindle motor on, forward direction (F)
only for power feed.
0.
Pivot the quill downfeed levers outward, feeling for
gear engagement as you go (jiggle the levers as
necessary to fully engage – no gap between lever
and its slot in the lever hub).
.
The quill will now descend under power until "0"
on the depth collar approaches the scale datum, at
which point the quill will retract rapidly to position ()
unless — recommended — it is restrained by light
pressure on the downfeed levers.
7
Select a Feed Rate, then set the
Advertisement
