Quality Machine Tools PM-940M User manual

1
PM-940M 10-2016 v1.indd
Model PM-940M
6-speed gear head
9-1/2 x 40 inch table
Powered table (X axis)
Powered headstock (Z axis)
Power downfeed version available
Quill DRO & depth stop
Weight (including cast iron stand) 1300 lbs
701 Parkway View Drive
Pittsburgh, PA 15205
Copyright © 2016
Quality Machine Tools, LLC
Heavy duty milling machine
Table
power feed
Coarse downfeed
& power down-
feed (if installed)
Quill DRO
Fine downfeed
Control box
(movable for
best viewing
location)
1.5 HP (1.1 kW)
220 Vac spindle
motor
Z-axis motor
(headstock elevation)
Spindle speed
selection

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PM-940M 10-2016 v1.indd
PM-940M
FAQ
This manual contains essential safety advice on the proper setup, operation, maintenance, and service
of the PM-940M mill. Failure to read, understand and follow the manual may result in property damage
or serious personal injury.
There are many alternative ways to install and use a milling machine. As the owner of the machine you
are solely responsible for its proper installation and safe use. Consider the material contained in this
manual to be advisory only. Precision Matthews cannot be held liable for injury or property damage during
installation or use, or from negligence, improper training, machine modifications or misuse.
This manual describes PM-940M machines as shipped from June 2016. There may be detail dif-
ferences between your specific machine and the information given here (with little or no impact on
functionality). If you have questions about any aspect of the manual or your machine, please email
us at [email protected]. Your feedback is welcomed.
My mill doesn’t
run
R8 collets won't go
into the spindle
110 Vac power connected?
E-Stop button out?
Power switch IN?
Circuit breaker tripped?
The locating screw could be in
too far. See Section 4, Mainte-
nance.

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PM-940M 10-2016 v1.indd
Section 1 FEATURES & SPECIFICATIONS
MODEL PM-940M MILLING MACHINE
General information
The PM-940M is a robust “square column” mill designed for day-in, day-out use in the busy model shop. With an
all-up weight of ovr 1300 lbs it can handle far more than the typical small machine, including end mills up to 1-1/4”
and face mills up to 3”. For precise control of cutter depth there is a worm-driven quill downfeed with graduated dial
and DRO, completely independent of headstock up/down position. Two versions of the mill are available, with and
without power downfeed.
The reversible spindle runs in high-quality (ISO355) tapered-roller bearings enclosed in a 3” diameter quill with
coarse and fine downfeed options. An oil-filled gearbox provides 6 spindle speeds from 90 to 1970 rpm. Features
of the headstock include choice of manual or powered elevation on dovetailed ways, ± 90 degree tilt, and a quill
depth stop for drilling operations. The 40” x 9-1/2" table is powered in the X axis by a variable-speed dc motor. Table
movement in both X and Y axes is along scraped dovetailed ways.
Floor plan

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PM-940M 10-2016 v1.indd
PM-940M SPECIFICATIONS
Dimensions
Weight, machine only 1000 lb net
Weight, cast iron stand 300 lb net
Size, including stand See floor plan
Stand footprint W 18-1/2 in. x D 26-3/4 in.
Tray W 24 in. x D 34 in.
Electrical
Power requirement 220V, 60 Hz, single phase
Full load current
9A, spindle motor only
Motors
Main (spindle) Cap-start induction, 220V 2 HP, 1725 rpm
X-axis (table traverse) Variable speed gear motor, 1A
Z-axis gear motor (elevation) 220V 120W
Headstock
Vertical travel* 20 in.
Left-right tilt 90 degrees clockwise/counter-clockwise
Spindle
Speeds (rpm) Low range 90 to 345, High range 670 to 1970
Internal taper R8
Top end 6 splines, 28 mm OD
Quill travel 5 in.
Quill diameter 3 in.
Spindle nose to table 20-3/4 in., max, 2" min
Spindle centerline to column cover
11 in. to pleated cover
Drawbar
7/16 - 20, 18 mm wrench
Table
Size W 40 in. x D 9-1/2 in.
Surface height over floor, on stand
Approx 34-3/4 in.
Maximum load 400 lb, table-centered, less if overhanging
Leadscrews Acme, inch pitch, 10 tpi
Left-right table traverse (X-axis)* 26 in.
Front-back cross travel (Y-axis)* 12 in.
T-slots (3) 14 mm wide, 80 mm centerlines
* DRO installation may limit these numbers
T-slot dimensions

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PM-940M 10-2016 v1.indd
Section 2 INSTALLATION
THESE ARE THE MAIN POINTS TO WATCH OUT FOR!
But read the following pages for more information
Handling the mill is at least a two-man job.
Hand-crank the headstock down until the spindle nose is just clear of
the table. Remove the hand crank, and set it aside.
Lifting gear – sling, hoist or forklift – must be rated for at least 1500 lb.
Working location of the mill must allow:
Full left-right travel of the table
Access to the back of the column (Z-axis leadscrew maintenance)
Headroom for the Z-axis motor
Power requirement is 220V, 60Hz, 1φ, 15A circuit protection (spindle
motor only, 9A full load).
Extension cord not recommended; if no alternative, use 12 AWG not
longer than 20 ft.
Before connecting power be sure that:
The machine is on a firm footing.
The Z-axis (headstock) and X-axis (table) motors are safely situ-
ated, not installed in their working locations. Don’t let them dangle
on the cables!
There are no clamps or locks on moving parts.
The gearbox contains oil – check the sight glass at right of the
headstock.
The gear levers are set for the lowest speed: Hi-Lo to L, 1-2-3 to 1.
The gears are fully engaged – hand rotate the spindle forward and
back while applying light pressure on each lever, listening for the
click as gears engage.
•
•
•
•
1.
2.
3.
•
•
•
1.
2.
3.
4.
5.
6.
Remove the Z-axis
crank handle before
moving the head-
stock under power

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PM-940M 10-2016 v1.indd
UNCRATING THE MILL
The PM-940M is shipped in two packing cases. Uncrat-
ing the stand is straightforward. If available, use a forklift
to handle the mill; if not, an engine hoist such as that
shown in Figure 2-3 may be used.
Setting up the stand
A suggested procedure:
Lower the stand packing case onto a dolly or pallet
jack.
Remove the packing materials, then roll the stand to
its working location.
Slide the stand off the dolly or pallet jack.
The stand comprises two iron castings, a hollow casing
and a tray. The back side of the casing has holes for pip-
ing and wiring to and from a coolant pump which may be
located within the casing. A coolant drainpipe is provided
in the tray casting. Rotate the tray to bring the drain to
the back.
Check local codes for machine tool fastening require-
ments. If none is specified, leveling mounts are rec-
ommended. Use mounts with a 1/2-13 threaded stem,
and a load capacity of not less than 400 lb per mount.
Mounts with a smooth underside such as nylon allow
minor repositioning even with the mill in place. Thread
length should be about 3 inches (longer stems won’t fit
in the pockets).
With the stand in its approximate working location, level
it using the rim of the tray casting. Final leveling should
be done with the table as the reference surface once the
machine has been installed and bolted to the stand.
Time-saving suggestion
The tray casting slides freely on top of the stand. This
makes it difficult to keep the holes aligned when the mill
is lowered into place. One way to save effort is to an-
chor the tray to the stand with two or more wood dowels
tapped in from above. The dowels need to be sized to
allow them to be driven through when the time comes to
install the mounting bolts on the mill.
PREPARING THE MILL
The following assumes an engine hoist will be used.
Some experimentation may be necessary. A suggested
procedure:
With the mill remaining on the shipping pallet, re-
move all packing materials except for the single
sheet under the mill.
Roll the engine hoist onto the bottom sheet, Figure
1.
2.
3.
1.
2.
Figure 2-1 Cast iron stand
Figure 2-2 One style of leveling mount
2-3. Set the upper arm of the hoist as far out as pos-
sible — but not beyond the point where its lifting
capacity is less than 1500 lb.
Remove the side rail(s) from the bottom sheet of the
pallet. This allows the hoist to be rolled further in
to bring the lifting chain just in front of the column,
Figure 2-4.
Check that the headstock (Z-axis) is fully lowered
(spindle nose just clear of the table), then run a sling
“basket style” under the headstock, as Figure 2-5.
Wrap a soft cloth around the sling to prevent dam-
age to the paintwork and the tilt scale.
3.
4.

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PM-940M 10-2016 v1.indd
Figure 2-3 Moving the mill - Stage 1
Very slowly lift the mill, controlling any tendency for
it to swing as it clears the pallet.
Remove the shipping pallet, then roll the mill close
to its working location.
Hoist the mill to its working height, then lower it onto
the prepared tray/stand assembly.
Moving the mill and stand as one assembly
Instead of unbolting the mill, save time by fork-lifting the
entire assembly. You will need two 1” diameter steel rods
or thick-wall iron pipe about 40” long. These will span
the stand (hole locations arrowed in Figure 2-6) with 8 or
5.
6.
7.
Figure 2-4 Moving the mill - Stage 2
Figure 2-5 Moving the mill - Stage 3
Figure 2-6 Holes for lifting rods
Holes, total 4, are in similar locations at back and right side
9 inches clear each side of the tray. Be careful with bal-
ance – crank the headstock down as far as it will go.

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PM-940M 10-2016 v1.indd
Figure 2-10 Z-axis leadscrew & helical gears
The leadscrew nut, arrowed, is attached to the headstock
FINAL ASSEMBLY & CLEANUP
Unfinished metal surfaces are protected by thick grease
and/or paper. Carefully remove these using a plastic
paint scraper, disposable rags and a light-oil type de-
greaser such as WD-40. Install the X axis and Y axis
handwheels using special washers, Figure 2-7 . Level
the mill using the table surface for reference. Oil the
ways and leadscrews. Remove the cover on the back
of the column to check for grease on the helical gears,
Figure 2-10.
INSTALLING THE TABLE (X-AXIS) MOTOR
This may have been factory installed
Installing the X-axis power feed motor takes care and
attention. The mounting bracket, a casting with two hex-
head clamp screws, is pre-installed. On the out-facing
surface of the bracket loosely install two hex-head M8
screws with split and plain washers. The motor assem-
bly hooks onto these screws, and is carefully lowered to
engage its drive pinion with the larger pinion pre-installed
on the X-axis leadscrew. To prevent the gears meshing
too tightly, place a greased strip of standard bond paper
(about 0.004” thick) between them before gently press-
ing down on the assembly. Tighten the screws, then
crank the X handwheel to remove the paper.
Do not power the X-axis motor at this time!
Crank the handwheel a few turns in both directions.
If the motor is properly installed, there should be little
resistance on the handwheel, and no noise other than
what is typical of straight-cut gears. If other noises are
heard, it may be that the motor is slightly tilted down.
This may be correctable by tightening the attachment
screws. If not, it may be necessary to insert metal shims
(say 0.005”) between the mounting bracket and motor
assembly – location arrowed in photo.
INSTALLING THE ELEVATION (Z-AXIS) MOTOR
This may have been factory installed
Test fit the Z-axis motor, checking for hole alignment.
The leasdscrew may have been displaced in shipping.
This is correctable by light pushing and pulling on the
coupler at the upper end of hte leadscrew. Key the gear-
box output shaft to the leadscrew coupler, then hand-
crank the leadscrew as necessary to align the bolt holes.
Install and tighten the four bolts.
REMOVE the crank handle before running
the motor
Figure 2-8 Washer for X & Y-axis handwheels
Figure 2-9 X-axis table motor
Shims on both sides of the bracket, arrowed, may be needed
for quiet meshing of the gears

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PM-940M 10-2016 v1.indd
POWER-UP PROCEDURE
Depending on the available 220V wall outlet, install a
6-15 or 6-20 plug on the mill power cord. Be sure the
green/yellow ground wire is attached (it may be tagged
PE = Protective Earth).
Before connecting power be sure that:
The spindle (main) motor switch, lower right of the
control panel, is set to S.
The Z-axis crank handle is removed.
There are no clamps or locks on moving parts.
The gearbox contains oil – check the sight glass at
right of the headstock.
The gear levers are set for the lowest speed: Hi-Lo
to L, 1-2-3 to 1.
The gears are fully engaged – hand rotate the spin-
dle forward and back while applying light pressure
on each lever, listening for the click as gears en-
gage.
Referring to Section 3, test the mill as follows:
Connect power.
Be sure the E-stop (Emergency) button is not pushed
in (it pops out when twisted clockwise), Figure 3-1.
Press the green Power button. Expect to hear a click
from the control box – this is a contactor energizing.
The power lamp should light.
Check the emergency function by pressing the E-
stop button. The power lamp should go out, de-en-
ergizing the contactor, disabling all electrics.
If this doesn’t happen, the E-stop function is defec-
tive, and needs attention
Restore power by twisting the E-stop button firmly
clockwise until it pops out.
Center the Left-Right lever on the table power feed.
Rotate the speed control knob fully counter-clock-
wise, then clockwise about 45 degrees.
Switch on the table motor. Test the power traverse
function by selecting Left traverse, followed by stop
(center), then Right.
Check that the limit switch assembly stops motion
correctly when actuated by the left and right stop
blocks, Figure 3-4.
Crank handle removed? Headstock locking levers
loose? Run the headstock up the column, Z-axis
motor switch (bottom left) set to Up. Check that the
motor stops as the upper limit switch is actuated,
Figure 2-11.
Check for no obstructions, then run the headstock
down to the lower limit.
Expect to hear a click from the control box when
Up is selected. This is one of the two Z-axis motor
1.
2.
3.
4.
5.
6.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
contactors energizing. A similar click from the other
contactor should be heard when Down is selected.
Figure 2-11 Z-axis (elevation) limit switches
These are actuated by the block attached to the headstock
TEST RUN PROCEDURE
Do not leave the machine unattended during this
procedure
Gear levers set to L and 1 (90 rpm)? Gears fully
engaged?
Test the spindle motor by setting the motor switch,
upper right on control box panel, to F (forward) and
R (reverse) in turn.
Run the spindle at 90 rpm for a few minutes, then
stop.
Select each of the available speeds in turn (L-2, L-3,
H-1, etc.). Check gear engagement each time, then
run for a few minutes.
Optional
After a few hours of run time you may wish to drain the
oil to flush out any residue from the manufacturing pro-
cess. This may result in smoother, quieter running, to-
gether with longer service life.
Refill the gearbox with the recommended oil, see
Section 4
The machine should now be ready for normal opera-
tions.
1.
2.
3.
4.

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PM-940M 10-2016 v1.indd
Everyday precautions
• This machine is intended for use by experienced users familiar with metal-
working hazards.
• Untrained or unsupervised operators risk serious injury.
• Wear ANSI-approved full-face or eye protection at all times when using the
machine (everyday eyeglasses are not reliable protection against flying par-
ticles).
• Wear proper apparel and non-slip footwear – be sure to prevent hair, clothing
or jewelry from becoming entangled in moving parts. Gloves – including tight-
fitting disposables – can be hazardous!
• Be sure the work area is properly lit.
• Never leave chuck keys, wrenches or other loose tools on the machine.
• Be sure the workpiece, toolholder(s) and machine ways are secure before
commencing operations.
• Use moderation: light cuts, low spindle speeds and slow table motion give
better, safer results than “hogging”.
• Don’t try to stop a moving spindle by hand – allow it to stop on its own.
• Disconnect 220 Vac power from the mill before maintenance operations such
as oiling or adjustments.
• Maintain the machine with care – check lubrication and adjustments daily
before use.
• Clean the machine routinely – remove chips by brush or vacuum, not com-
pressed air (which can force debris into the ways).
No list of precautions can cover everything.
You cannot be too careful!

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PM-940M 10-2016 v1.indd
Section 3 USING THE MILL
MILL SIMILARITIES
PM-940M vs. PM932M
The PM-940M is a larger version of the PM-932M. The
two mills are similar in many respects. In this manual,
photos of the PM-932M are used to illustrate features
of the PM-940M. Aside from slight variations in appear-
ance, such as the type of spindle motor, key differences
between the two mills are:
Gear selectors (spindle speed) are on the left side of
the PM-940M headstock,vs. front panel for the PM-
932M.
The quill locking lever is left of the headstock for
power downfeed versions of both mills. Mills without
power feed have a front-mounted locking lever.
The Z-axis motor (headstock elevation) is controlled
by a single rotary switch on the PM-940M, by sepa-
rate UP/DOWN buttons on the PM-932M.
The control box is attached directly to the left side of
the PM-932M headstock; it is suspended from a mov-
able beam on the PM-940M.
ELECTRICAL CONTROLS
Connect the mill to a 220Vac outlet. Press the Power
lamp switch, top center, to energize the control circuit
(the green lamp should light). This is a latching switch
– press once to energize, press again to de-energize.
The E-stop button, bottom right, is in series with the
Power switch. Like the Power switch it de-energizes
1.
2.
3.
4.
•
•
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 clockwise to release.
The spindle drive motor is controlled by a rotary
switch:
F= Forward (clockwise, looking down, used for most
milling/drilling operations)
R= Reverse (counter-clockwise, looking down)
S= Stop
• Before switching on the spindle motor, be sure
that both stages are properly engaged. Hand-rotate
(jiggle) the spindle forward and back while applying
light pressure on each gear-shift knob, listening for the
click as the gears engage.
Allow the spindle to stop completely before shift-
ing gears
SPINDLE SPEEDS
This is a gear-head machine with a constant speed mo-
tor and a two-stage, six speed gearbox. The first stage
(L-H) selects the speed range, high or low, and the sec-
ond stage (2-3-1) selects a specific speed within that
range.
•
L-1 90
L-2 210
L-3 345
H-1 670
H-2 1180
H-3 1970
Figure 3-1 PM-940M control box
Spindle
speeds
(rpm)
Figure 3-2 Speed selector knobs

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PM-940M 10-2016 v1.indd
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!
INSTALLING & REMOVING TOOLING
The spindle and drawbar are designed for R-8 taper
collets, drill chucks and other arbors with the standard
7/16”-20 internal thread. The drawbar is threaded into
the R-8 device by a few turns of the upper nut, which
is solidly pinned to the bar. With sufficient length of the
thread engaged, run the lower nut down as far as it will
go, then tighten it using two wrenches, 17 mm upper, 19
mm lower (or 11/16” and 3/4”). To keep the spindle from
turning too freely in this procedure, select a low speed
such as L-1. Another way of tightening the lower nut is
to hold the spindle using a 6-spline wrench, nominal size
28 mm.
To remove the R-8 device, loosen the lower nut one half
turn or less, then tap the top of the drawbar with a brass
or dead-blow hammer to unseat the taper. Unscrew the
drawbar by turning the upper nut with one hand while
supporting the R-8 device with the other hand.
Replace the drawbar cap to protect bearings and
spline.
Keep in mind that the table, vise and work-
piece can be damaged by falling tools and
drill chucks. The cutting tool itself can also
be damaged in the same way.
Figure 3-3 Spindle and drawbar
Figure 3-4 Y-axis handwheel and X-axis locks
The limit switch assembly, arrowed, prevents over-travel when
the X-axis is power driven. Separate microswitches, left and
right, are actuated by adjustable spring-cushioned stop blocks
(3).
MOVING THE TABLE
Conventionally, left-right movement of the table is said
to be along the X-axis (also called “longitudinal travel”
or “traversing”). Front-back movement is on the Y-axis,
sometimes called “cross travel”.
Each axis has a leadscrew with handwheel and gradu-
ated dial with 0.001” divisions, 0.1” per revolution, Fig-
ure 3-4. If the mill is not equipped with digital readouts
(DROs), the table can be accurately positioned by
counting whole turns and divisions, keeping leadscrew
backlash in mind. This means that table motion must
always be in the same direction up to the point of refer-
ence, then on to the desired location, see “X & Y axis
positioning”, following.
Be sure to loosen the X-axis lock screws
before moving the table, especially under
power

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PM-940M 10-2016 v1.indd
X & Y-AXIS POSITIONING BY COUNTING
DIVISIONS
For all spindle positioning operations, with or
without DROs, avoid using the quill lock.
Why? On vertical mills of this type, including the heavier
knee mills, locking the quill may offset the spindle by one
or two thousandths of an inch. If the edge of the work-
piece has been “found” in the quill-locked condition, this
will affect placement of holes drilled thereafter. Instead,
lower the quill with the fine downfeed control. This is
worm driven, so it stays where it’s put without locking.
NOTE: This does not apply to operations calling for pre-
cise depth control, such as milling. For such operations
the quill must be locked to maintain a given depth of
cut.
Y-axis positioning is illustrated by Figure 3-7. A hole is
to be drilled 0.25” on the Y-axis relative to the front edge
of a workpiece in a vise, or otherwise clamped to the
table.
Install an edge-finder in collet or chuck (a tip diam-
eter of 0.2” is assumed).
1.
Figure 3-5 Y-axis locks
X-AXIS POWER FEED
Power lamp
The power lamp, a small LED on the right-facing sur-
face, lights when the Power switch is on.
Direction lever
Before setting the lever to L or R, make sure the X-axis
locks are FREE, and the speed control is fully counter
clockwise (zero speed).
Rapid Traverse
Press the Rapid Traverse button (momentary type) to
drive the table rapidly in the direction set by the L-R le-
ver.
Reset button
If the power feed unit draws more than 3.5 amps for more
Figure 3-6 X-axis power feed
than 10 seconds, the overload switch will cut power and
the reset button will pop out. Press the STOP button on
the main control box to disconnect power. Investigate
and resolve power feed problems – such as X-axis locks
not free, or gears too tightly engaged. Allow a cooling
interval, press the reset button, then restore power.
Limit switch
Stop blocks on the front surface of the table can be in-
dependently set to limit left-right travel, Figure 3-4, (3).
To reposition a stop block, loosen its attachment screw,
then tap it if needed to free the square nut in the dovetail
slot. (Slot dimensions: 10 degree sides, 0.3” deep, width
tapers from approx. 0.5” to 0.4”.)
Figure 3-7 Spindle positioning example

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PM-940M 10-2016 v1.indd
Lock the X-axis by tightening both levers, Figure 3-4
(1).
If the reference edge is already to the back the spindle
centerline, do nothing; if not, rotate the Y-axis hand-
wheel clockwise to send the workpiece backwards
(toward the column).
Engage the fine downfeed, Figure 3-8.
With the spindle running, lower the quill as neces-
sary using the fine downfeed handwheel; bring the
table forward (counter-clockwise), stopping at the
point where the edge-finder just makes contact (the
tip jumps out of line). Stop the spindle.
While holding the Y-axis handwheel to prevent move-
ment, zero the dial, then re-tighten the dial thumb-
screw, Figure 3-4 (2).
Raise the quill, then rotate the handwheel one exact
full turn counter-clockwise (0.1”) to bring the refer-
ence edge to the spindle centerline.
Rotate the handwheel 2-1/2 turns counter-clockwise
to bring 50 on the dial opposite the datum; the spindle
is now exactly 0.25” behind the reference edge.
Be sure to loosen the X-axis locking levers be-
fore moving the table, especially under power.
DRO
The DRO is in metric mode when switched on. Press the
mm/in button to display inches. By pressing and holding
the Up arrow (incrementing) or Down arrow (decrement-
ing) the display can be set to a chosen value. The longer
the buttons are held down, the faster the change in dis-
played value. Zero the display at any time by pressing
the ON/O button.
Switch off the DRO when not in use!
Replace the battery by sliding the cover (small arrow) to
the right. For longer battery life use a 1.5V silver oxide
battery, SR44 or equivalent.
QUILL DOWNFEED
Mills without power downfeed
The quill is controlled in two different ways, coarse and
fine.
In the drilling mode, coarse feed, the mill functions like
a standard drill press – lower the quill using any of the
three downfeed levers to rotate the lever hub counter-
clockwise. For milling operations the lever hub is disen-
gaged, and the quill is controlled by the fine downfeed
handwheel. The quill is locked by a lever at lower right of
2.
3.
4.
5.
6.
7.
8.
Figure 3-8 Quill downfeed controls
The lever hub (1) is full-time connected to the quill pinion. The
fine control handwheel (2) is connected by a worm gear to the
sleeve (3), and is free to rotate — doing nothing to the quill
— unless it is coupled to the lever hub (1). Couple sleeve (3)
to hub (1) by tightening knob (4).
the headstock front panel, Figure 3-9.
Coarse feed (Figure 3-8)
For drilling operations, loosen knob (4), allowing the le-
ver hub to rotate independently of sleeve (3). If desired,
set the depth stop, Figure 3-9.
Fine feed (Figure 3-8)
For milling operations calling for precise, repeatable
control of tool depth, tighten knob (4) to engage the ta-
pered face of hub (1) with the internal taper on sleeve
(3). Tighten the Z-axis locks, Figure 3-14.
Rotate the fine control handwheel (2) to raise or lower
the quill. Before switching to fine control, it is usually a
good idea to run the depth stop up to the top. Lower the
quill by rotating the fine control knob clockwise, position-
ing it precisely either by counting divisions on the gradu-
ated dial, or by reference to the front panel DRO (digital
readout). Use the locking lever to hold the quill firmly in
position.
If you are counting divisions be aware of backlash in the
worm drive. This means that the handwheel must always
be turning in the same direction throughout the entire
process, from setting a reference level to subsequent
cutting passes at specific depths – see the backlash dis-
cussion in “Moving the table”, above. Using the DRO

15
PM-940M 10-2016 v1.indd
Mills without power downfeed (continued)
Figure 3-9 DRO, depth stop & quill locking lever
Mills without power downfeed
– which has no backlash issues – is less laborious, but
remember that the quill is spring-loaded. This calls for
care when releasing the quill locking lever prior to repo-
sitioning the quill downward. If the fine control knob has
been allowed to disengage (backed off counter clock-
wise), the quill will jump up by 0.01” or more. To avoid
this, make sure the fine control is firmly clockwise, lightly
loading the quill rack, before releasing the locking lever.
QUILL DOWNFEED
Mills with power downfeed
This is a factory-installed option. Mills shipped without
this option cannot be retrofitted.
Power downfeed, Figure 3-10, can be used to reduce
workload in many routine operations including drill-
ing, reaming, honing, and hole boring with single point
tools.
Three feed rates are available:
0.1 mm (~ 0.004”) per spindle revolution
0.18 mm (~ 0.007”)
0.26 mm (~ 0.010”)
The quill is controlled by hand in two different ways,
coarse and fine. The power downfeed system is de-
scribed later in this section.
In the drilling more, coarse feed, the mill functions like a
standard drill press – pull the rearmost downfeed lever
up and over toward you to rotate the downfeed lever hub
clockwise, lowering the quill. For milling operations the
downfeed levers are right-shifted to engage the down-
feed lever hub with the fine control handwheel, which
may then be rotated clockwise to lower the quill under
precise control.
Coarse feed
For drilling operations swing the downfeed levers to
the left to disengage the lever hub from the fine control
handwheel. Tighten the downfeed lever stop screw to
lock the levers in position, thus preventing unintended
engagement of the power downfeed.
The graduated depth collar can be used to set a depth
stop for drilling as follows:
Tighten the Z-axis locks, Figure 3-14.
Lower the quill to bring the point of the drill down to
the desired end point, then tighten the quill locking
lever, Figure 3-10.
Loosen the depth collar clamp lever to free the depth
collar from the lever hub.
Rotate the depth collar clockwise as far as it will go
(it should indicate approximately 5 inches, see Figure
3-11). When the depth collar clamp lever is re-tight-
ened, this will define the quill’s end stop.
Re-tighten the depth collar clamp lever.
Unlock the quill. While observing the DRO reading,
raise and lower the quill a few times to be sure the
quill stops at the desired end point.
1.
2.
3.
4.
5.
6.

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PM-940M 10-2016 v1.indd
Fine feed
For surfacing and other milling operations calling for pre-
cise tool depth increments, use the fine control hand-
wheel.
With the spindle stationary, set the Power Feed
Engage and Feed Rate Selectors to OFF.
Tighten the Z-axis locks, Figure 3-14.
Loosen the downfeed lever stop screw to free the
downfeed levers.
Pivot the levers outward, testing for gear engage-
ment as you go (jiggle the levers as necessary to
fully engage, no gap between lever and its slot in the
lever hub).
Lower the quill to the desired depth by rotating the
fine control handwheel clockwise (only).
Tighten the quill locking lever.
1.
2.
3.
4.
5.
Mills with power downfeed (continued)
Figure 3-10 Power downfeed controls
Figure 3-11 Using the depth collar as a stop

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PM-940M 10-2016 v1.indd
Power downfeed example
In Figure 3-13 a previously drilled hole is to be enlarged
using a single point boring tool. What follows is one of
several possible procedures.
With the quill fully retracted (1), lower the headstock
to bring the cutting tool just clear of the upper sur-
face of the workpiece.
Lock the Z-axis, Figure 3-14.
With the cutting tool inboard of the drilled hole, lower
the quill by hand to the desired end point for the tool
(2).
Lock the quill, then set the depth collar to zero.
Tighten the depth collar clamp lever.
Release the quill locking lever, allowing the quill to
retract fully, position (1).
Spindle stopped? Select a Feed Rate, then set the
Power Feed Engage knob to ON. Jiggle the spin-
dle and Fine Control by hand to ensure the power
feed is properly engaged.
Stay clear of the Fine Control knob — this will
rotate when the spindle runs.
Turn the spindle motor on, forward direction (F)
only for power feed.
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 (1)
unless — recommended — it is restrained by light
pressure on the downfeed levers.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Figure 3-12 Quill locking lever (power feed version)
Mills with power downfeed (continued)
Stop the spindle before touching the Power
Feed Engage or Feed Rate Selector knobs.
Key points to remember, referring to Figure 3-10:
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.
•
•
•
•
•
•
•
USING THE POWER DOWNFEED SYSTEM
Figure 3-11 Hole boring with power downfeed
Note: Use the graduated dial on the fine control hand-
wheel for guidance only. It has 120 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 3-12.

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PM-940M 10-2016 v1.indd
HEADSTOCK ELEVATION (Z-AXIS)
See Figure 3-1 for the Z-axis motor controls.
Figure 3-14 Z-axis locking levers
Figure 3-15
Z-axis hand crank
Be sure to loosen
the Z-axis locks
before moving the
headstock.
Remove the crank
handle before
moving the head-
stock under power
TILTING THE HEADSTOCK
In routine operations the user relies on squareness of the
spindle relative to both axes of the table. Front-to-back
squareness set at the factory, and is not adjustable (by
everyday methods), but in the other plane the headstock
can be set to any angle up to 90 degrees either side
of the normal vertical position. [Because re-establishing
true vertical – tramming — on any mill is a time consum-
ing process, most machinists look first for other ways of
handling the project instead of tilting the head.]
The headstock is secured by three nuts spaced 120 de-
grees apart, one underneath and one either side, Fig-
ure 3-18. The headstock is top-heavy, and may swing
suddenly to either side unless a helper is on hand to
restrain it. Using a 24 mm wrench, testing for moveabil-
ity as you go, carefully loosen the nuts by degrees. Be
especially careful if the head has not been moved before
– the paint seal may let go without warning. (First-time
tilting may also call for unusual effort on the wrench.)
Set the headstock to the desired angle by reference to
the tilt scale, then re-tighten the nuts. Bear in mind that
this is good only to approximately ± 0.25o, so a more
accurate means of angle measurement will be needed if
the project calls for precise tilting.
Figure 3-16 Z-axis limit switches

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PM-940M 10-2016 v1.indd
Figure 3-17 Headstock tilted 45ocounter clockwise
Figure 3-18 Headstock tilt nuts (two of three)
TRAMMING THE HEADSTOCK
“Tram”, short for trammel, means accurate alignment
— in this case adjusting the headstock tilt to bring the
spindle to a known angle — usually 90 degrees — rela-
tive to the table.
As shipped, the mill is set to zero tilt, squared accurately
enough for initial “out of the box” test drillings, etc. For
more demanding project work thereafter, the spindle
needs to be set at precisely 90 degrees, in other words
trammed. “Out of tram” may show up as an offset of a
few thousandths between entry and exit of a deep hole,
or as a scalloped effect when surfacing a workpiece with
a large-radius fly cutter, exaggerated in Figure 3-19.
Tramming is done by fine-tuning the headstock tilt angle.
Tram is typically checked by attaching a dial indicator to
some form of “sweepable” holder installed in the spindle,
the aim being to adjust tilt for the same reading on either
side of the X axis. The longer the radius arm, the greater
the sensitivity.
Figure 3-20 Sweeping holder for dial indicator
This example shows a rectangular section aluminum bar with
threaded holes allowing the choice of two sweep diameters, 6”
and 10”, measured from spindle centerline to indicator tip. The
smaller sweep can be used for front-to-back tramming, also
left-to-right as here. For more sensitive left-to-right tramming,
use the larger sweep.
Figure 3-20 shows a typical shop-made holder; it has a
threaded arbor allowing the choice of two radius arms,
6 and 10 inches measured from spindle centerline to in-
dicator tip. A collet is used to hold the arbor, in this case
5/8” diameter. The dimensions are arbitrary, but note that
the indicator must be firmly attached, and the arm rock-
solid relative to the indicator spring force (which can be
considerable on plunger-type indicators).
A suggested procedure for re-establishing tram:
Disconnect power.
Set the headstock to the approximate zero degree
position on the tilt scale, then tighten the three nuts
1.
2.
Figure 3-19 Head tilt can affect surface flatness

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PM-940M 10-2016 v1.indd
enough to avoid unexpected headstock movement.
Remove the vise and clean the table surface.
Set a 1-2-3 block (or other precision-ground block)
on the table under the indicator probe.
Switch on the quill DRO.
Lower the spindle using fine downfeed to give a half-
scale indicator reading (exact location isn’t impor-
tant, but remember the reading).
Note both the dial indicator and DRO readings, then
back off the fine downfeed at least a couple of turns
to avoid collision when sweeping.
Set the spindle drive to H-3 (this will allow you
to sweep the indicator holder easier from side to
side).
Reposition the 1-2-3 block to the opposite location
on the table.
Swing the indicator holder to the new location, then
lower the spindle – fine downfeed again – to give the
same dial indicator reading as in step (7).
If the headstock is perfectly trammed – highly unlikely at
the first shot – the DRO reading should be as in step (7).
If not, loosen the nuts just enough to allow the headstock
to be tapped a fraction of a degree in the direction called
for, then re-tighten the nuts. (The “tap” can be anything
from a gentle hand-slap to a rap with a soft-face dead-
blow mallet).
Repeat steps (4) through (10) until satisfied with the
tram, tightening the nuts as you go. This will likely call
for several iterations. There is no “right” tram; the ac-
ceptable difference in side-to-side readings depends on
project specs. As a starting point, aim for ± 0.001” on a
radius of 5 or 6 inches.
A similar procedure may be used to check tram in the
Y-axis, front to back. The difference here is that there
is that Y-axis tram is established in manufacture, and
can be adjusted only by shimming the column-to-base
interface. This is a two-person procedure, requiring an
engine hoist or some other means of un-weighting the
column and headstock (see Section 2, Installation).
3.
4.
5.
6.
7.
8.
9.
10.
Tramming calls for patience on any mill! Expect
to tighten and re-check at least three times (sim-
ply tightening the bolts can affect the tram).
INSTALLING & INDICATING A VISE
For routine milling operations the workpiece is held in a
precision vise. For the PM 940M a 4” vise is highly suit-
able. “Indicating” means checking the alignment of the
fixed (back) vise jaw relative to the axis of table motion.
Install the T-bolts and align the vise by eye. With one of
the clamp nuts snug, but not tight, tighten the other one
just short of fully-tight (but tight enough so the vise won’t
budge without a definite tap from a dead-blow mallet).
A typical setup for indicating is shown in Figure 3-21.
You need to make sure that the spindle does not ro-
tate throughout the procedure. There is no spindle lock,
but set the gears for the lowest spindle speed (L-1), then
take up any backlash by pushing against the indicator
holder.
Set the indicator tip against the upper edge of a preci-
sion reference bar or, if not available, use the front face
of the fixed jaw of the vise instead (check for dings, hone
if necessary). Adjust the Y-axis to pre-load the indicator
to mid range at the tightly-clamped side of the vise, then
lock the Y-axis.
Note the indicator reading, then watch the indicator as
you traverse the table slowly toward the loosely clamped
side. Ideally, there should be no discrepancy between
the indicator readings at the two ends — unlikely at the
first attempt. Return the table to the starting point, then
repeat the process, tapping the vise in as you go. Re-
peat the process as often as necessary for the desired
accuracy, progressively tightening the “looser” nut. Now
fully tighten both nuts, and re-check again (tightening a
nut can itself introduce significant error). An established
Figure 3-21 Indicating the vise
The tip of a standard dial indicator, arrowed, rides along the side face
of a ground reference bar (or the front face of the back jaw).