This Manual is Bookmarked
Operating Instructions and Parts Manual
Combination Belt/Disc Sander
Model 31A
WMH TOOL GROUP, Inc.
2420 Vantage Drive
Elgin, Illinois 60124
Ph.: 800-274-6848
Part No. M-0460267
Revision G1 6/08
Copyright © 2008 WMH Tool Group, Inc.
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Table of Contents
Warranty and Service ..............................................................................................................................2
Table of Contents....................................................................................................................................3
Warning...................................................................................................................................................4
Introduction .............................................................................................................................................6
Specifications..........................................................................................................................................6
Dimensions .............................................................................................................................................7
Unpacking...............................................................................................................................................8
Contents of the Shipping Container......................................................................................................8
Assembly ................................................................................................................................................9
Installing Sander on Stand ...................................................................................................................9
Installing and Tracking Abrasive Belt..................................................................................................10
Installing Fence..................................................................................................................................10
Installing Abrasive Disc ......................................................................................................................11
Installing Table...................................................................................................................................11
Dust Outlet and Cord Plate.................................................................................................................12
Switch (Single Phase Model)..............................................................................................................12
Electrical Connections ...........................................................................................................................12
Adjustments ..........................................................................................................................................14
Platen Adjustment..............................................................................................................................14
Sanding Table Adjustment .................................................................................................................14
Work Stop..........................................................................................................................................15
Belt Arm Positioning...........................................................................................................................15
Operation ..............................................................................................................................................16
Template Forms.................................................................................................................................16
Fence/Table.......................................................................................................................................16
Types of Operations...........................................................................................................................17
Maintenance..........................................................................................................................................18
Lubrication.........................................................................................................................................18
Extension Cords.................................................................................................................................13
Guide to Sanding Belts and Discs..........................................................................................................19
Troubleshooting.....................................................................................................................................20
Replacement Parts................................................................................................................................20
Parts List: 31A Sander Body Assembly ..............................................................................................21
31A Sander Body Assembly...............................................................................................................23
Parts List: 31A Stand Assembly (1PH) ...............................................................................................24
31A Stand Assembly (1PH)................................................................................................................25
Parts List: 31A Stand Assembly (3PH) ...............................................................................................26
31A Stand Assembly (3PH)................................................................................................................27
Electrical Connections (1 Phase) ...........................................................................................................28
Electrical Connections (3 Phase) ...........................................................................................................29
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Warning
As with all machines, there is a certain amount of hazard involved with the use of this sander. Use the
machine with the respect and caution demanded where safety precautions are concerned. When normal
safety precautions are overlooked or ignored, personal injury to the operator can result.
Read, understand and follow the safety and operating instructions found in this manual. Know the
limitations and hazards associated with this machine.
Electrical grounding. Make certain that the machine frame is electrically grounded and that a ground
lead is included in the incoming electrical service. In cases where a cord and plug are used, make certain
that the grounding plug connects to a suitable ground. Follow the grounding procedure indicated in the
National Electrical Code.
Eye safety. Wear an approved safety shield, goggles, or glasses to protect eyes. (NOTE: Common
eyeglasses are only impact-resistant, they are not safety glasses.)
Personal protection. Before operating the machine, remove tie, rings, watch and other jewelry and roll
up sleeves above the elbows. Remove all loose outer clothing and confine long hair. Protective type
footwear should be used. Where the noise exceeds the level of exposure allowed in Section 1910.95 of
the OSHA Regulations, use hearing protective devices. Do not wear gloves.
Guards. Keep the machine guards in place at all times when the machine is in use. If removed for
maintenance purposes, use extreme caution and replace guards on completion of the maintenance task
before operating the sander. DO NOT operate the machine with the guards off except for the belt end
guard which swings away to allow for contour sanding. Keep that guard in place except when contour
sanding and swing it back into position immediately after completing the contour sanding task.
Work area. Keep the floor around the machine clean and free of scrap material, saw dust, oil and other
liquids to minimize the danger of tripping or slipping. Make certain the work area is well lighted and that a
proper exhaust system is used to minimize dust. Powermatic recommends the use of anti-skid floor strips
on the floor area where the operator normally stands and that each machine’s work area be marked off.
Provide adequate work space around the machine.
Avoid accidental starting: Make certain motor switch is in off position before connecting power to the
machine.
Operator position. Maintain a balanced stance and keep your body under control at all times. Do not
over-reach. Do not stand in line with the belt in the direction that it is moving when the work stop is not in
use.
Belt and Disc Direction. Proper belt direction is from the idler pulley towards the drive pulley. Proper
disc rotation is counterclockwise facing the disc. CAUTION: Sand on the section of the disc from the
center to the left edge. DO NOT use the right hand portion for sanding.
Housekeeping. Before turning on machine, remove all extra equipment such as keys, wrenches, scrap,
and cleaning rags away from the machine.
Careless acts. Give the work you are doing your undivided attention. Looking around, carrying on a
conversation, and “horseplay” are careless acts that can result in serious injury.
Disconnect machine before performing any service or maintenance.
Hand safety. Keep fingers and hands away from the belt or disc. DO NOT clear sawdust from the table
with the hands; use a brush. On small or thin parts, use a push stick or jig to keep the hands from
contacting the abrasive. If using the fence, avoid getting fingers too close to the fence to prevent pinching.
Never wear gloves while operating the sander.
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Machine capacity. Do not try to force the sander to remove material faster than the power available from
the drive motor. The use of light pressure on either disc or belt sanding and moving the part back and
forth will maximize belt or disc life, help to minimize the chances of an accident and keep the force within
the capacity of the drive motor.
Machine adjustments. Make all machine adjustments with power off except belt tracking. Belt tracking
should be checked manually before starting the sander, but final adjustment may have to be made after
starting up the sander.
Table safety. Be sure the table is locked in position before placing stock on it and that its front edge is
within 1/16” or less, of the disc or belt.
Job completion. If the operator leaves the machine area for any reason, the sander should be turned
"off" and the abrasive belt and disc should come to a complete stop before his/her departure. In addition,
if the operation is complete, he should clean the sander and the work area. Never clean the sander with
power "on" and never use the hands to clear sawdust and debris; use a brush.
Replacement parts. Use only Powermatic or factory authorized replacement parts and accessories;
otherwise the warranty and guarantee is null and void.
Misuse. Do not use this Powermatic sander for other than its intended use. If used for other purposes,
Powermatic disclaims any real or implied warranty and holds itself harmless for any injury or damage
which may result from that use.
If you are not thoroughly familiar with the operation of sanders, obtain advice from your supervisor,
instructor or other qualified person.
Drugs, alcohol, medication. Do not operate this machine while under the influence of drugs, alcohol, or
any medication.
Health hazards. Some dust created by power sanding, sawing, grinding, drilling and other construction
activities contains chemicals known to cause cancer, birth defects or other reproductive harm. Some
examples of these chemicals are:
* Lead from lead-based paint.
* Crystalline silica from bricks and cement and other masonry products.
* Arsenic and chromium from chemically-treated lumber.
Your risk from these exposures varies, depending on how often you do this type of work. To reduce your
exposure to these chemicals, work in a well-ventilated area, and work with approved safety equipment,
such as those dust masks that are specifically designed to filter out microscopic particles.
Familiarize yourself with the following safety notices used in this manual:
This means that if precautions are not heeded, it may result in minor injury and/or
possible machine damage.
This means that if precautions are not heeded, it may result in serious or possibly even
fatal injury.
- - SAVE THESE INSTRUCTIONS - -
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Introduction
This manual is provided by WMH Tool Group, Inc. covering the safe operation and maintenance
procedures for a Powermatic Model 31A Combination Belt/Disc Sander. This manual contains instructions
on installation, safety precautions, general operating procedures, maintenance instructions and parts
breakdown. This machine has been designed and constructed to provide years of trouble free operation if
used in accordance with instructions set forth in this manual. If there are any questions or comments,
please contact either your local supplier or WMH Tool Group. WMH Tool Group can also be reached at
Specifications
Model Number.............................................................................31A .................................................31A
Stock Number (1 Phase model).........................................1791291K .......................................................
Stock Number (3 Phase model)......................................................... ....................................... 1791292K
Abrasive Belt Size (in.) ............................................................ 6 x 48 ..............................................6 x 48
Disc Size (in.)................................................................................12 ................................................... 12
Table Working Height (in.) ......................................... 34 disc, 36 belt ................................34 disc, 36 belt
Sanding Arm Locking Positions (deg.) ........................... 0, 45 and 90 ....................................0, 45 and 90
Disc Table Size (in.) .......................................................... 17-1/4 x 9 ........................................17-1/4 x 9
Disc Table Tilt (deg.)..................................................15 up, 45 down ............................... 15 up, 45 down
Belt Table Size (in.) ..................................................... 13-1/4 x 7-1/2 ..................................13-1/4 x 7-1/2
Belt Table Tilt (deg.) .............................................................45 down ..........................................45 down
Disc Speed (RPM).....................................................................2375 ............................................... 2375
Belt Speed (SFPM)....................................................................2410 ............................................... 2410
Dust Port Diameter (in.)...................................................................4 ..................................................... 4
Dust Collection Minimum CFM Required......................................400 ................................................. 400
Motor...........................................................1-1/2HP, 1PH, 115/230V .......................2HP, 3PH, 230/460V
(pre-wired 115V), 14/7A
(pre-wired 230V) 7/3.5A
Overall Dimensions (LxWxH)(in.)........................24 x 31-1/4 x 54-1/2 ........................ 24 x 31-1/4 x 54-1/2
Net Weight (lbs.)..........................................................................247 ................................................. 247
Shipping Weight (lbs.)..................................................................275 ................................................. 275
The above specifications were current at the time this manual was published, but because of our policy of
continuous improvement, WMH Tool Group reserves the right to change specifications at any time and
without prior notice, without incurring obligations.
Read and understand the entire contents of this manual before attempting set-up
or operation! Failure to comply may cause serious injury.
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Dimensions
Figure 1
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1
1
Miter Gauge Assembly
Unpacking
Bag of Fasteners, contains:
2
4
4
4
2
Socket Head Cap Screws, M10x25 – AA
Hex Head Screws, M8 x 25 – BB
Lock Washers, M8 – CC
Open shipping container and check for shipping
damage. Report any damage immediately to
your distributor and shipping agent. Do not
discard any shipping material until the Sander is
assembled and running properly.
Flat Washers, M8 – DD
Flat Washers, M10 – EE
Compare the contents of your container with the
following parts list to make sure all parts are
intact. Missing parts, if any, should be reported
to your distributor. Read the instruction manual
thoroughly for assembly, maintenance and
safety instructions.
1
1
Owner's Manual (not shown)
Warranty Card (not shown)
Container #2 (Stand):
1
1
1
Stand with motor
Dust Outlet
Contents of the Shipping Container
Bag of Fasteners, contains:
Container #1 (Sander):
4
2
2
2
2
Pan Hd. Flanged Screws, M6 x 12 – FF
Pan Head Screws, M5 x 12 – GG
Pan Head Screws, M4 x 8 – HH
Lock Washers, M4 – JJ
1
1
1
1
1
Belt/Disc Sander
Abrasive Belt, 6” x 48”, 60 grit
Abrasive Disc, 12” dia., 60 grit
Disc Table Assembly
Fence Assembly
Flat Washers, M4 – KK
Figure 2
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Assembly
Tools required:
wrenches – 10, 13 and 17mm
hex (Allen) wrench – 8mm
Cross-point screwdriver
Installing Sander on Stand
Refer to Figure 3:
1. If the machine is to be secured to the floor,
use high quality lag screws through the four
holes inside the bottom of the stand. If using
a mobile base, be sure to lock the wheels
before assembling, operating or making
adjustments to the sander. (A mobile base
for your sander – part no. 708118 – is
available from WMH Tool Group.)
2. The sander is shipped with the belt arm in
horizontal position. Pull out on the index pin
and raise the arm to vertical position, as
shown in Figure 3. This will better balance
the sander as you place it on the stand.
Allow the index pin to pop back in to ensure
the belt arm is secure.
Figure 3
3. Position the sander on the stand making
sure to orient it properly, as shown. Also,
make sure the loose end of the drive belt
below the disc is pulled down and guided
through the rectangular hole in the stand.
4. Secure the sander to the stand with four M8
x 25 hex head screws (BB), four M8 lock
washers (CC) and four M8 flat washers
(DD). NOTE: Hand tighten the screws only
until all four are inserted; then tighten them
completely with a 13mm wrench.
Refer to Figure 4:
5. The drive belt is already mounted on the
disc pulley behind the disc, as shown in
Figure 4. However, it should be checked to
ensure that it is in the pulley groove.
Figure 4
(viewed from front of machine)
6. Loosen the top hex nut on the tensioning
screw with a 17mm wrench, and rotate the
lower hex nut to raise the motor platform
high enough to position the drive belt
around the motor pulley.
7. When the belt is in the motor pulley groove,
tension the belt by rotating the lower hex nut
downward out of the way, and tightening the
top hex nut to lower the platform. When the
belt is tensioned properly, tighten the lower
hex nut against the platform to secure the
setting.
NOTE: Proper tension is achieved when there is
moderate deflection (about 1/2”) in the belt
midway between the two pulleys. After a period
of use, re-check the belt tension, as new belts
have a tendency to stretch slightly during the
breaking-in process.
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Installing and Tracking Abrasive Belt
To install the abrasive belt, proceed as follows
Refer to Figures 5 and 6:
1. Loosen the knob (A) and swing the belt end
guard (B) out of position.
2. Remove the side cover by unscrewing the
two knobs holding it, and sliding the tabs of
the side cover out of the slots of the sander.
3. Loosen the tension knob (C). This will lower
the top drum, providing slack for installing
the abrasive belt.
4. Slide the abrasive belt onto the drums until it
is centered on them.
Figure 5
5. Tighten the tension knob (C).
IMPORTANT: Do not over tension, as this can
cause the abrasive belt to stretch and weaken.
The abrasive belt must be properly tracked
before operating. (Tracking refers to the position
of the abrasive belt on the drums while they are
in motion.) Proceed as follows:
6. Check tracking manually at first, by moving
the belt downward with your hand while the
machine is off. The abrasive belt should
remain at the center of the drums.
7. If the belt veers to one side or the other,
loosen the locking wheel (D) and rotate the
tracking knob (E) either left or right until the
belt centers itself. When manual tracking
appears successful, turn the machine on for
a moment and confirm that the abrasive belt
will remain centered during operation. If
needed, continue fine-tuning the adjustment
with the tracking screw (E). It may require a
combination of tension knob (C) and
tracking knob (E) adjustment to achieve a
proper setting.
Figure 6
8. When satisfied, tighten the locking wheel
(D) against the belt arm to secure the
setting.
9. Re-install side cover and secure with the
knobs. Swing the end guard (B) back into
position and re-tighten the knob (A).
Installing Fence
Refer to Figure 7:
Pinch Point. Before installing
the fence, adjust it to a right angle position
as shown, and tighten the knob to secure.
1. Tilt the belt arm into horizontal position, and
place the fence against the platen in the
position shown.
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2. Insert the two M10x25 socket head cap
screws (AA), with two M10 flat washers
(EE), through the fence base and into the
threaded holes on the pivot plate.
3. Tighten the screws with an 8mm hex
wrench.
4. Check that the gap between fence and
sanding belt is about 1/16”. If it is greater
than 1/16”, loosen (do not remove) the four
screws on the sides of the fence assembly
with a hex wrench, and push the fence
toward the belt until the proper gap is
attained.
5. Re-tighten the four screws.
See under “Adjustments” for further instruction
on adjusting the fence.
Installing Abrasive Disc
Refer to Figure 8:
Figure 7
1. Loosen the two screws on the front panel
with a 10mm wrench, and pull out on the
front panel. The front panel will not remove
from the sander, but this will allow more
room for positioning the abrasive disc.
2. Remove the backing from the abrasive disc
to expose the adhesive, and carefully center
it on the sander’s metal disc. Press the
abrasive disc firmly, working from the center
out to prevent creases or air bubbles.
3. Tighten the two screws on the front panel.
When removing an old abrasive disc, use
mineral spirits or a similar cleaning product to
remove any residual adhesive from the sander’s
metal disc before installing a new abrasive.
Figure 8
Installing Table
Refer to Figure 9:
1. On both sides of the sander body, loosen
the locking wheels (A), and pull the trunnion
holders (B) out far enough to allow
clearance between trunnion holders and
sander body.
2. Install the table by sliding the table trunnions
into the slots of the trunnion holders. See
Figure 9 inset. Be careful not to damage the
angle pointer on the left trunnion holder.
3. Slide the trunnion holders (B) back in, and
re-tighten the locking wheels (A).
See under “Adjustments” for further instruction
on adjusting the table.
Figure 9
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Dust Outlet and Cord Plate
Refer to Figure 10:
1. Install the dust outlet using the four M6 x 12
pan head flanged screws (FF).
2. Single Phase model: Feed the electrical
plug through the hole in the stand, and slide
the cord plate through also. Secure the cord
plate to the stand using the two M5x12 pan
head screws (GG) as shown.
Switch (Single Phase Model)
Refer to Figure 11:
Figure 10
1. Place the push button switch into the
rectangular opening from inside the stand.
2. Secure the switch to the outside of the
stand, using two M4x8 pan head screws
(HH), two M4 lock washers (JJ) and two M4
flat washers (KK).
Electrical Connections
Electrical connections must
be made by
a
qualified electrician in
compliance with all relevant codes. This
machine must be properly grounded to help
prevent electrical shock and possible fatal
injury.
Figure 11
(single phase model)
The 31A Sander is equipped with either a single
phase 115/230 volt motor (pre-wired 115V); or
a three phase 230/460 volt motor (pre-wired
230V).
The three phase sander is not equipped with a
plug. You may either install a UL/CSA listed plug
suitable for 230 or 460 volt operation, or “hard-
wire” the sander directly to a service panel. If the
Sander is to be hard-wired to a panel, make
sure a disconnect is available for the operator.
During hard-wiring of the machine, make sure
the fuses have been removed or the breakers
have been tripped in the circuit to which the
Sander will be connected.
Make sure the voltage of your power supply
matches the specifications on the motor plate of
the sander.
The 115V attachment plug supplied with the
sander must be replaced with a UL/CSA listed
plug suitable for 230V operation. Contact your
local authorized WMH Tool Group service center
or qualified electrician for proper procedures to
install the plug. The sander must comply with all
local and national codes after the 230 volt plug
is installed.
Converting from 115 Volt to 230 Volt
(Single Phase Only)
To convert from 115V to 230V (1 phase model),
consult the diagrams inside the cover of the
motor junction box, to determine how to switch
the motor leads. A similar diagram is also found
at the back of this manual.
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Converting from 230 Volt to 460 Volt
(Three Phase Only)
Consult the wiring diagram inside the starter box
cover. A diagram is also included on page 29 of
this manual. The Jointer must comply with all
local and national codes after being wired.
1. Remove the starter box cover and adjust the
dial on the relay (see Figure 12) as close as
possible to the amperage of the Jointer
motor at 460V, as listed on the motor plate.
2. Move the fuse (Figure 12) from the 230V
slot to the 460V slot.
3. Re-connect the incoming leads to the motor
for 460 volt operation, as shown in the
wiring diagram.
4. If using a plug, install a proper UL/CSA
listed plug suitable for 460 volt operation.
Figure 12
(Three Phase model only)
Three-Phase Test Run
On the three-phase unit, after wiring has been
completed, you should check that the wires
have been connected properly:
Extension Cords
1. Connect machine to power source and
press the start button.
An extension cord is not recommended; if
possible, position your Sander within reach of
the power supply. If an extension cord becomes
necessary, make sure the cord rating is suitable
for the amperage listed on the machine’s motor
plate. An undersize cord will cause a drop in line
voltage resulting in loss of power and
overheating.
2. The sanding disc and belt should move in
accordance with the arrow directions on the
machine. If the movement is backward, stop
the machine and disconnect machine
from power.
3. Switch any two of the three wires at "R,S,T".
Use the chart in Figure 12a as a general guide
in choosing the correct size cord. If in doubt, use
the next heavier gauge. The smaller the gauge
number, the heavier the cord.
Grounding Instructions
This machine must be grounded. In the event of
a malfunction or breakdown, grounding provides
a path of least resistance for electric current to
reduce the risk of electric shock.
Recommended Gauges (AWG) of Extension Cords
Extension Cord Length *
Improper connection of the equipment-
grounding conductor can result in a risk of
electric shock. The conductor with insulation
having an outer surface that is green with or
without yellow stripes, is the equipment-
grounding conductor. If repair or replacement of
the electric cord or plug is necessary, do not
connect the equipment-grounding conductor to a
live terminal.
25
50
75
100 150 200
Amps
feet feet feet feet feet feet
< 5
16
16
14
12
10
10
16
16
14
12
10
NR
16
14
12
10
10
NR
14
12
12
10
12
5 to 8
NR
NR
NR
NR
NR
8 to 12
12 to 15
15 to 20
21 to 30
10
NR
NR
NR
NR
10
Check with a qualified electrician or service
personnel if the grounding instructions are not
completely understood, or if in doubt as to
whether the tool is properly grounded.
NR
NR
*based on limiting the line voltage drop to 5V at 150% of the
rated amperes.
NR: Not Recommended.
Repair or replace a damaged or worn cord
immediately.
Figure 12a
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Adjustments
Before putting power to the sander, inspect the
machine thoroughly. Check to ensure that all
screws are tight, all mechanical functions work
freely, belt runs freely and tracks properly, and
the disc runs freely, does not come into contact
with the guard or table, and the abrasive
remains firmly adhered to the sander’s metal
disc.
Turn the motor on and check for proper rotation
direction of the belts. The sanding belt should
move from the idler pulley toward the drive
pulley, while the disc should rotate counter-
clockwise with the operator facing the disc.
Arrow labels are affixed to the sander to indicate
these directions.
Platen Adjustment
The platen should not require attention on your
new sander. After prolonged use, however, the
platen may occasionally need re-adjustment. To
do this, proceed as follows.
Refer to Figure 13:
1. Swing the end guard out of position and
remove the side cover. Remove the
abrasive belt.
2. Using a 6mm hex wrench, loosen the two
socket head cap screws inside the belt arm
and shift the platen as needed. The platen
should be 1/32” to 1/16” above the tangent
points of the pulleys and in contact with the
belt at both ends. A straight edge can be
used with the abrasive belt to align the
platen, as shown in Figure 13.
Figure 13
3. Re-tighten the socket head cap screws.
Sanding Table Adjustment
Refer to Figures 14 and 15:
The sanding table may be adjusted from any
angle from 15 degrees up, to 45 degrees down.
To adjust, loosen the locking wheels (A) on both
sides and pivot the table to the desired angle as
shown on the trunnion scale (B). Re-tighten the
locking wheels (A).
A 45-degree stop (C) is located under the table.
Use an angle measuring device to confirm that
the angle of the table against the stop is 45
degrees. If it is not, adjust by loosening the hex
nut and screwing the stop in or out as needed.
Re-tighten hex nut.
Figure 14
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A zero-degree stop screw (D) is located behind
the disc. The block should be set for quick
placement of the table to the zero position (90
degree table). The block must be swung out of
position for the table to be tilted downward. If
major adjustment of the zero-degree stop is
necessary, loosen the socket head cap screws
(E) and raise or lower the bracket. For fine
adjustment, loosen the hex nut (F) and turn the
stop screw (D) in or out as needed. Re-tighten
hex nut (F).
Periodically check zero position on the table by
using a combination square. The angle between
the table and disk should be 90 degrees when
the trunnion pointer is at zero.
Figure 15
Work Stop
Your sander is equipped with a work stop for
use with the belt arm in the horizontal position
(see Figure 23). When installed, the work stop
will prevent a work piece from being thrown from
the belt. If removed for through-sanding, the
work stop should be immediately reinstalled
after the through-sanding operation (unless the
fence attachment is used in its place for 45-
degree or vertical positions of the arm). Use a
10mm hex wrench to remove or install the work
stop.
Belt Arm Positioning
Your sander is equipped with an index pin
arrangement to lock the belt arm in 0-degree,
45-degree, and 90-degree positions. To position
the belt arm:
Figure 16
1. Loosen the locking handle shown in Figure
16.
2. Pull out on the index pin (Figure 17), and
swing the belt arm into the desired position.
Then release the index pin.
3. Check that the index pin has gone into
position by attempting to move belt arm
back and forth.
4. Re-tighten locking handle (Figure 16).
When positioning the arm at any non-standard
angle, make sure the locking handle is tightened
securely.
NOTE: If the locking handle conflicts with the
motion of the belt arm, pull up on the handle and
rotate it out of the way, then release it, making
sure it re-seats itself properly.
Figure 17
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Operation
The belt and disc sander can be equipped with a
variety of abrasives and grit sizes to handle a
wide variety of materials, from soft woods to
hardened steel. It can be used to rapidly remove
material and produce a mirror finish. Using
various types of fixtures, they can be used to
sand template forms, angles, freehand contours,
and flats on edges, surfaces and ends.
Figure 18
Template Forms
A template similar to that shown in Figure 18
can be made to facilitate sanding multiple pieces
to the same size.
Fence/Table
Refer to Figure 19:
The fence attachment is used with the belt
sander and can be positioned alternately as a
table (with the belt arm in upright position) or as
a fence (with the belt arm in horizontal position).
The fence attachment surface has a slot for a
miter gauge when the attachment is used as a
table. The fence attachment can be tilted
between 90-degree and 45-degree angles by
loosening the knob (A) on the center portion of
the attachment. Manually move the fence to the
desired angle and tighten the knob (A).
Figure 19
To position the fence at an angle across the belt
(for skew sanding as shown in Figure 20), use a
3/16 hex wrench to loosen the two socket head
screws (B, Figure 19). Rotate the fence
attachment by sliding it around the bolts using
the curved slot (C). When the desired position is
reached, re-tighten the screws (B).
Figure 20
To change the fence attachment from fence to
table, or vice-versa, remove the two socket head
screws (B). Remove the fence attachment and
rotate the pivot plate (D, Figure 21) 180 degrees
lining the holes up with the holes in the sander.
Place the fence attachment on the pivot plate
with the table perpendicular to the belt. Line up
the slots with the holes on the pivot plate and
the sander, then replace and tighten the screws
(B).
Always mount the base of
the fence attachment through the pivot plate
(D, Figure 21). Failure to do so could lead to
damage to the fence attachment and also
ruin the sanding belt.
Figure 21
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The chart on page 19 lists the various grits and
materials used and lists the grit symbols. It is
generally better to start with a slightly coarser
abrasive than would seem practical because it
will give faster material removal, generate less
heat, and will sand more freely. As it dulls, it will
tend to act like a finer abrasive.
Too often, the user will expect one belt or disc to
take care of all situations; however, the
materials to be sanded, the desired finish and
the amount of material to be removed all have
an effect on the selection grade of grit, abrasive
material and construction. Contact suppliers of
abrasive belts and discs for recommendations
on the work to be done.
Figure 22
Types of Operations
Flat surface sanding is demonstrated in Figure
22, where the major surface is sanded in a flat
plane.
Edge sanding is a common type of long surface
sanding that can be done using the fence. See
Figure 23.
Edge sanding and flat surface sanding can also
be done with the belt arm in a vertical position,
by using the fence assembly as a table.
Figure 23
Miters and compound miter cuts can be sanded
using the table and the miter gauge. Special
fixtures can also be designed to use on the table
for circular and form sanding.
Contour sanding can be done using the idler
pulley with the end guard swung down. See
figure 24.
Always swing the end guard
back into position and fasten it down
immediately after the completion of any
operation that required the end guard to be
moved out of position.
Keep in mind that abrasive
sanding develops heat, so burns can occur
on wood if you try to remove material too
fast. With metal, it may be necessary to have
a container of water nearby to keep the
workpiece cool enough to hold it by hand.
Figure 24
Flat surface and contour sanding can be done in
the horizontal, 45-degree, and vertical position
of the belt arm. To change position, pull out the
index pin and swing arm to the desired position,
then release index pin (see Figure 17).
17
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Maintenance
Before doing maintenance
on the sander, disconnect it from the
electrical supply by pulling out the plug or
switching off the main switch! Failure to
comply may cause serious injury.
Make periodic or regular inspections to ensure
that your sander is properly adjusted, that all
screws are tight, the belt is in good condition,
that dust has not collected in the motor or
electrical enclosures and there are no loose or
worn electrical fittings or wiring.
If the power cord is worn, cut, or damaged in
any way, have it replaced immediately.
Keep the fence and table surfaces clean and
free of rust.
Lubrication
Periodically lubricate the following parts on the
31A Sander.
Use a good quality, non-hardening grease on:
• Idler slide (Figure 25)
• table trunnion (shown in Figure 9)
Figure 25
Use SAE No. 10 Oil on these:
• internal threads of table locking wheels (A,
Figure 14)
• belt arm index pin (shown in Figure 3)
All bearings used on the Model 31A Sander are
sealed for life and require no lubrication.
18
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Guide to Sanding Belts and Discs
19
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Troubleshooting
Trouble
Probable Cause
Remedy
Disconnected from power source.
Incorrect voltage.
Check connection to source.
Make sure power source matches
voltage of sander, as shown on motor
name plate.
Sander will not start.
Switch is not activating.
Motor is faulty.
Repair or replace switch.
Repair or replace motor.
Raise platen to 1/32” beyond the apex
of the drum. See page 14.
Platen is shifted or worn.
Abrasive belt won’t
track properly.
Belt is stretched unevenly.
Drum is worn.
Replace belt.
Replace drum.
Abrasive disc comes
free of aluminum
disc.
Clean adhesive off aluminum disc,
then re-apply adhesive and re-mount
abrasive disc.
Improper bond.
Abrasive belt tension is inadequate.
Excessive pressure.
Tighten abrasive belt (page 10).
Reduce pressure against belt.
Properly tension drive belt (page 9).
Properly tension drive belt (page 9).
Replace key.
Abrasive belt slips or
stalls on application
of pressure.
Drive belt is loose.
Drive belt is loose.
Aluminum disc stalls.
Disc shaft key is missing.
Using too much pressure when
sanding.
Reduce pressure against belt.
Excessive abrasive
belt replacement.
Stroke across full width of belt to
disperse wear.
Not using full width of belt.
Index pin is stuck.
Broken spring.
Remove arm and free index pin.
Remove arm and replace spring.
Belt arm won’t index.
Replacement Parts
Replacement parts are listed on the following pages. To order parts or reach our service department, call
1-800-274-6848, Monday through Friday (see our website for business hours, www.powermatic.com).
Having the Model Number and Serial Number of your machine available when you call will allow us to
serve you quickly and accurately.
20
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Parts List: 31A Sander Body Assembly
Index No. Part No.
Description
Size
Qty
1...............31A-1.......................Cast Base.............................................................................................. 1
2...............31A-2.......................Dust Chute (Disc) .................................................................................. 1
3...............31A-3.......................Sanding Disc......................................................................................... 1
4...............31A-4.......................Disc Table............................................................................................. 1
5...............31A-5.......................Trunnion................................................................................................ 2
6...............31A-6.......................90° Stop Bracket.................................................................................... 1
7...............31A-7.......................Trunnion Holder..................................................................................... 2
8...............31A-8.......................Set Screw...........................................................M10 x 55 .................... 2
9...............31A-9.......................Lock Knob..........................................................M10 x 57 .................... 1
10.............31A-10.....................Ring Spanner ........................................................................................ 2
11.............31A-11.....................Sanding Belt Guard ............................................................................... 1
12.............31A-12.....................Idler Bearing Housing............................................................................ 1
13.............31A-13.....................Shaft ..................................................................................................... 1
14.............31A-14.....................Key.....................................................................6 x 6 x 25 ................... 2
15.............BB-6204ZZ ..............Bearing...............................................................6204ZZ....................... 2
16.............31A-16.....................Aluminum Drum..................................................................................... 2
17.............31A-17.....................Hex Nut (L.H. Threads).......................................M16 x 2...................... 1
18.............31A-18.....................Knob ..................................................................................................... 1
19.............31A-19.....................Index Pin............................................................................................... 1
20.............31A-20.....................Knob ..................................................................M6 x 12...................... 3
21.............31A-21.....................Pan Head Screw w/ Flange ................................M6 x 12...................... 3
22.............31A-22.....................Locking Handle...................................................M10 x 1.25P............... 1
23.............31A-23.....................Lock Handle .......................................................M10 x 45 .................... 1
24.............31A-24.....................Side Plate Casting................................................................................. 1
25.............31A-25.....................Rocker Arm ........................................................................................... 1
26.............31A-26.....................Hex Head Bolt....................................................................................... 1
27.............31A-27.....................Platen.................................................................................................... 1
28.............31A-28.....................Side Cover ............................................................................................ 1
29.............BB-6205ZZ ..............Bearing...............................................................6205ZZ....................... 2
30.............31A-30.....................Pan Head Screw w/ Flange ................................M5 x 8........................ 1
31.............31A-31.....................Bearing Housing.................................................................................... 1
32.............TS-1551061.............Lock Washer ......................................................M8.............................. 3
33.............TS-1504051.............Socket Head Cap Screw.....................................M8 x 25...................... 3
34.............31A-32.....................Key.....................................................................6 x 6 x 40 ................... 1
35.............31A-33.....................Shaft ..................................................................................................... 1
36.............31A-34.....................Special Washer ..................................................................................... 2
37.............31A-35.....................Pulley.................................................................................................... 1
38.............31A-36.....................Belt Guard............................................................................................. 1
39.............31A-37.....................Guard.................................................................................................... 1
40.............TS-1550041.............Flat Washer........................................................M6.............................. 2
41.............TS-1551041.............Lock Washer ......................................................M6.............................. 2
42.............31A-38.....................Hex Head Bolt....................................................M6 x 12...................... 2
43.............31A-39.....................Hex Head Bolt....................................................M6 x 20...................... 2
44.............TS-1551041.............Lock Washer ......................................................M6.............................. 2
45.............31A-40.....................Work Rest ............................................................................................. 1
46.............31A-41.....................Pivot Plate............................................................................................. 1
47.............31A-42.....................Fence Table .......................................................................................... 1
48.............31A-43.....................Fence End Bracket................................................................................ 2
49.............31A-44.....................Fence Base........................................................................................... 1
50.............31A-45.....................Long Link .............................................................................................. 1
51.............31A-46.....................Short Link.............................................................................................. 1
52.............31A-47.....................Socket Head Button Screw.................................M6 x 12...................... 4
53.............31A-48.....................Hex Head Bolt....................................................................................... 3
54.............31A-49.....................Set Screw...........................................................M8 x 35...................... 1
55.............TS-1540061.............Hex Nut..............................................................M8.............................. 2
56.............31A-50.....................Spring Pin...........................................................6mm dia x 20.............. 1
57.............31A-51.....................Set Screw...........................................................M6 x 8........................ 1
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58.............31A-52.....................Lock Washer ......................................................M16............................ 2
59.............31A-53.....................Hex Head Flange Bolt.........................................M6 x 20...................... 4
60.............31A-54.....................Lock Washer ......................................................M6.............................. 2
61.............31A-55.....................Hex Head Bolt....................................................M6 x 8........................ 2
62.............TS-1504041.............Socket Head Cap Screw.....................................M8 x 20...................... 2
63.............TS-2361081.............Lock Washer ......................................................M8.............................. 2
64.............31A-56.....................Hex Nut (L.H. Threads).......................................M16 x 2...................... 1
65.............31A-57.....................Socket Head Flat Screw .....................................M6 x 16...................... 1
66.............31A-58.....................Socket Head Flat Screw .....................................M8 x 20...................... 2
67.............31A-59.....................Spring.................................................................................................... 1
68.............31A-60.....................Pin......................................................................6mm dia x 16.............. 2
69.............TS-1550071.............Flat Washer........................................................M10 x 20 .................... 2
70.............TS-1505031.............Socket Head Cap Screw.....................................M10 x 25 .................... 2
71.............31A-61.....................Roll Pin...............................................................6mm dia x 24.............. 2
72.............31A-62.....................Roll Pin...............................................................6mm dia x 45.............. 4
73.............VB-A50....................V-belt .................................................................A50 ............................ 1
74.............31A-64.....................Roll Pin...............................................................5mm dia x 30............. 1
75.............31A-65.....................Stop Block............................................................................................. 1
76............. ................................Sanding Belt (local purchase) .............................12” dia........................ 1
77............. ................................Sanding Disc (local purchase) ............................6” x 48”....................... 1
78.............31A-68.....................Lock Knob..........................................................8mm x 20 ................... 1
79.............31A-69.....................Flat Washer........................................................M8 x 30 dia................. 1
80.............31A-70.....................Lock Knob..........................................................M10 x 1.25P............... 1
81.............31A-71.....................Tilting Scale........................................................................................... 1
82.............31A-72.....................Rivet...................................................................2mm dia. x 5............... 1
83.............31A-73.....................Pan Head Screw ................................................M6 x 8........................ 1
84.............31A-74.....................Pointer................................................................................................... 1
85.............TS-1550041.............Flat Washer........................................................M6.............................. 1
86.............TS-1550071.............Flat Washer........................................................M10............................ 2
87.............TS-1540041.............Hex Nut..............................................................M6.............................. 1
88.............TS-1523071.............Socket Set Screw...............................................M6 x 25...................... 1
89.............TS-1550031.............Flat Washer........................................................M5.............................. 1
90.............TS-1503051.............Socket Head Cap Screw.....................................M6 x 20...................... 2
91.............TS-1524051.............Socket Set Screw...............................................M8 x 20...................... 1
92.............31A-75.....................Hex Head Bolt....................................................M6 x 25...................... 1
93.............TS-1540041.............Hex Nut..............................................................M6.............................. 1
94.............31A-76.....................Pin......................................................................................................... 1
95.............31A-77.....................Miter Gauge Assembly .......................................................................... 1
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31A Sander Body Assembly
23
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Parts List: 31A Stand Assembly (1PH)
Index No. Part No.
Description
Size
Qty
1...............31A-78.....................Stand .................................................................................................... 1
2...............31A-79.....................Dust Outlet ............................................................................................ 1
3...............31A-80.....................Motor Pulley .......................................................................................... 1
4...............31A-81.....................Motor.....................................................1.5HP, 1PH, 115/230V .............. 1
5...............31A-82.....................Door...................................................................................................... 1
6...............31A-83.....................Door Latch Assembly............................................................................. 1
7...............31A-84.....................Motor Mounting Bracket......................................................................... 1
8...............31A-85.....................Cord Plate............................................................................................. 1
9...............31A-86.....................Strain Relief........................................................................................... 2
10.............TS-1533042.............Pan Head Screw ................................................M5 x 12...................... 2
11.............31A-87.....................Switch Box ............................................................................................ 1
12.............TS-1540031.............Hex Nut..............................................................M5.............................. 2
13.............31A-88.....................Star Washer (External) .......................................M5.............................. 2
14.............31A-89.....................Switch Cover......................................................................................... 1
15.............TS-1550021.............Flat Washer........................................................M4.............................. 4
16.............TS-1551021.............Lock Washer ......................................................M4.............................. 4
17.............31A-90.....................Pan Head Screw ................................................M4 x 8........................ 2
18.............31A-91.....................Pan Head Screw ................................................M5 x 8........................ 2
19.............31A-219...................Hex Head Screw ................................................M10 x 160 .................. 1
20.............31A-93.....................Self Tapping Screw ............................................M3.5 x 38 ................... 2
21.............31A-94.....................Switch ................................................................1PH............................ 1
22.............TS-1551061.............Lock Washer ......................................................M8.............................. 4
23.............31A-223...................Hex Head Screw ................................................M8 x 20...................... 4
24.............31A-95.....................Hex Head Screw ................................................M8 x 25...................... 4
25.............TS-1551061.............Lock Washer ......................................................M8.............................. 4
26.............TS-1550061.............Flat Washer........................................................M8............................ 12
27.............TS-1540061.............Hex Nut..............................................................M8.............................. 4
28.............31A-97.....................Motor Cord.........................................................1PH............................ 1
29.............31A-98.....................Power Cord ........................................................1PH............................ 1
30.............31A-99.....................Hex Nut.............................................................M10............................ 1
31.............31A-21.....................Pan Head Screw w/ Flange ................................M6 x 12...................... 4
32.............TS-1523041.............Socket Set Screw...............................................M6 x 12...................... 1
33.............31A-100...................Pan Head Screw ................................................M4 x 5........................ 2
34.............31A-101...................Spacer Washer...................................................................................... 2
35.............31A-99.....................Hex Nut.............................................................M10............................ 2
36.............TS-1550071.............Flat Washer........................................................M10............................ 2
37.............150527 ....................Sponge.................................................................................................. 2
38.............998630 ....................Strain Relief........................................................7P-2 ........................... 1
39.............31A-102...................Warning Label (not shown) .................................................................... 1
40.............6823013...................Black Stripe (not shown).................................................................per ft.
41.............3312341...................Powermatic Label (not shown)............................................................... 1
24
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31A Stand Assembly (1PH)
25
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Parts List: 31A Stand Assembly (3PH)
Index No. Part No.
Description
Size
Qty
1...............31A-78.....................Stand .................................................................................................... 1
2...............31A-79.....................Dust Outlet ............................................................................................ 1
3...............31A-80.....................Motor Pulley .......................................................................................... 1
4...............31A-103...................Motor........................................................2HP, 3PH, 230/460V .............. 1
5...............31A-82.....................Door...................................................................................................... 1
6...............31A-83.....................Door Latch Assembly............................................................................. 1
7...............31A-84.....................Motor Mounting Bracket......................................................................... 1
8...............31A-PBA..................Power Box Assembly............................................................................. 1
.................31A-208-1................Power Box............................................................................................. 1
.................31A-208-2................Strain Relief........................................................PGA13.5 .................... 2
9...............TS-1533042.............Phillips Pan Head Machine Screw ......................M5 x 12...................... 3
10.............6292880...................Star Washer (External) .......................................M5.............................. 1
11.............31A-91.....................Pan Head Screw ................................................M5 x 8........................ 1
13.............31A-213...................Switch Plate .......................................................................................... 1
14.............JC3-119...................Hex Flange Bolt..................................................M8 x 12...................... 2
15.............TS-1532042.............Phillips Pan Head Machine Screw ......................M4 x 12...................... 2
16.............31A-MSA .................Magnetic Switch Assembly .................................2HP,3PH,230V/460V.. 1
.................31A-16-1..................Power Cord ........................................................3PH............................ 1
.................31A-16-2..................Motor Cord.........................................................3PH............................ 1
.................31A-16-3..................Strain Relief........................................................PG25A-16B................ 2
.................31A-16-4..................Magnetic Switch .................................................................................... 1
17.............31A-219...................Hex Head Screw ................................................M10 x 160 .................. 1
18 ............TS-1551061.............Lock Washer ......................................................M8.............................. 4
19.............31A-223...................Hex Head Screw ................................................M8 x 20...................... 4
20.............31A-95.....................Hex Head Screw ................................................M8 x 25...................... 4
21 ............TS-1551061.............Lock Washer ......................................................M8.............................. 4
22 ............TS-1550061.............Flat Washer........................................................M8............................ 12
23 ............TS-1540061.............Hex Nut..............................................................M8.............................. 4
24.............31A-99.....................Hex Nut.............................................................M10............................ 1
25.............31A-21.....................Pan Head Screw w/ Flange ................................M6 x 12...................... 4
26 ............TS-1523041.............Socket Set Screw...............................................M6 x 12...................... 1
27.............31A-100...................Pan Head Screw ................................................M4 x 5........................ 2
28.............31A-101...................Spacer Washer...................................................................................... 2
29.............31A-99.....................Hex Nut.............................................................M10............................ 2
30.............TS-1550071.............Flat Washer........................................................M10............................ 2
31.............150527 ....................Sponge.................................................................................................. 2
32.............31A-102...................Warning Label (not shown) .................................................................... 1
33.............6823013...................Black Stripe (not shown).................................................................per ft.
34.............3312341...................Powermatic Label (not shown)............................................................... 1
26
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31A Stand Assembly (3PH)
27
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Electrical Connections (1 Phase)
28
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Electrical Connections (3 Phase)
29
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NOTES
30
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31
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WMH Tool Group, Inc.
2420 Vantage Drive
Elgin, Illinois 60124
Phone: 800-274-6848
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