8
PM 25MV v9 2021-12
Copyright © 2021 Quality Machine Tools, LLC
MOTOR CONTROLS
Before doing anything, check the installation in-
structions in Section 1
Connect the mill to a 110Vac outlet.
Press and release the green Power
ON
button to en-
ergize the control circuit; the tachometer should light.
This is a self-latching circuit – when the
ON
button is re-
leased, a contactor in the electrical box maintains power
until released by the red
OFF
button (also a momentary
switch).
•
The round orange E-stop button, right, is in series
with the
OFF
button. Like the
OFF
button it de-en-
ergizes the control circuit completely, but it should
be used only for its intended purpose – emergency
disconnect. Once the E-stop button is pushed in, it
stays in until twisted
firmly clockwise
to release.
•
Also in series with the Power and E-stop buttons is
a microswitch actuated by the acrylic Chip Guard in
front of the spindle. The motor will not run if the chip
guard is open.
•
The spindle motor is controlled by a three position
switch, Forward/Stop/Reverse, and a continuously-
variable speed control knob.
F
= Forward (cw, looking down, used for most milling
and drilling
O
= Stop
R
= Reverse (ccw, looking down)
Figure 3-1
Spindle motor controls
Also shown, arrowed, is the quill locking lever
Figure 3-2
Belt adjustment
SPINDLE SPEEDS
The PM-25MV is a belt-driven machine with two speed
ranges, (
L
) 50-1250 rpm and (
H
)100-2500 rpm.
To select a speed range, disconnect power, then remove
the blue motor cover (4 screws). Loosen the socket head
screws on each side of the motor, then swing the motor
forward to free the belt, Figure 3-2. Make sure that the
ribbed belt is properly engaged with the selected pair
of grooved pulleys, then re-tighten. Before powering up,
rotate the spindle by hand to check tracking and tight-
ness of the belt. Do not over-tighten – aim for ± ¼” slack
between the motor and spindle pulleys.
Excessive cutter noise, chatter, poor finish and
tool wear are often the result of too high a feed
rate, and/or too high a spindle speed. If unsure,
go slow!
Section 3 USING THE MILL
