3M Sander AT DIS7_PROHD User Manual

SERVICE INSTRUCTIONS FOR  
3M™ 12,000 RPM 5 in. (127 mm)  
and 6 in. (150 mm)  
RANDOM ORBITAL SANDERS  
3M™ Overhaul Service Kit  
The part number 20347, 3M™ Overhaul Service Kit, contains all the replacement parts that naturally  
wear over time and a straightforward manual to make servicing a 3M™ sander simple. Overhauling the  
Random Orbital Sander can be made even easier with the use of the above Service Tools. The Service  
Tools also reduce the chance of improper assembly.  
Part Number  
3MA0040  
3MA0021  
3MB0005  
3MA0010  
3MA0041  
3MA0042  
3MA0019  
3MA0938  
3MA0039  
3MA0062  
3MA0068  
3MA0007  
3MA0009  
3MA0014  
3MA0043  
3MA0008  
3MA0166  
3MA0016  
3MA1417  
Description  
Qty  
1
1
1
5
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
EXTERNAL RETAINING RING  
BEARING - 2 SHIELDS  
ROTOR  
VANE  
WOODRUFF KEY  
O-RING  
BEARING - 2 SHIELDS  
DOUBLE ROW ANGULAR CONTACT BEARING - 1 SEAL  
INTERNAL RETAINING RING  
INTERNAL MUFFLER  
MUFFLER INSERT  
VALVE  
VALVE SEAT  
VALVE SPRING  
O-RING  
VALVE STEM ASSEMBLY  
MUFFLER HOUSING  
SPACER  
INSTRUCTIONS FOR 5 in. AND 6 in. ROS OVERHAUL SERVICE KIT  
34-8700-5191-8  
1
Revision 10/03/07  
 
B) Remove the Ø 1 in. (28 mm) Hose SGV Swivel Exhaust  
Assembly from the Housing and SGV Skirt Adapter or  
SGV Shroud Adapter.  
4. For NV and CV machines follow the steps outlined in  
Section I below. For SGV machines follow the steps in  
Section III.  
C) Pull the SGV Retainer out of the bore of the Swivel  
Exhaust Assembly and remove the two O-rings.  
D) Remove the Vacuum Shroud or Vacuum Skirt from the  
Housing. Move onto step 2.  
I. This section is for CV and NV  
A) Place a clean felt Muffler all-the-way into the chamber of  
the Muffler Housing. Press the Bronze Muffler onto the  
Muffler Housing.  
2. Place the Speed Control to the midway position and  
remove the Retaining Ring. NOTE: If the machine is a  
vacuum model, the vacuum exhaust must be removed  
(see Section 1 above for removal) before the Retaining  
Ring can be removed with lock ring pliers. The Speed  
Control will now pull straight out. Remove the O-ring.  
3. Unscrew the Inlet Bushing Assembly from the Housing.  
Remove the Valve Spring, Valve, Valve Seat, Valve  
Stem and O-Ring.  
B) Screw the Muffler Housing assembly into the Housing  
until hand tight. Use a 21 mm socket/torque wrench  
combination to torque the Muffler Housing. Torque to 20  
in/lbs (2.25 Nm). For NV machines move onto C. For CV  
machines move onto Section II.  
C) Install the Non-Vacuum Shroud onto the Housing by  
working the shroud over and around the bottom of the  
housing flanges. Make sure the line up slots (on the  
Housing) and tabs (on the Shroud) are engaged. Move  
onto the ”Spindle, bearing shield and Shaft Balancer  
Assembly” Section.  
4. Press out the Spring Pin from the Housing and remove  
the Throttle Lever.  
ASSEMBLY INSTRUCTIONS  
II. This section continued from Section I for CV Ex-  
haust machines:  
NOTE: All assembly must be done with clean dry parts and  
all bearings are to be pressed in place by the correct tools  
and procedures as outlined by the bearing manufacturers.  
Housing Assembly:  
1. Install Throttle Lever into Housing with the Spring Pin.  
2. Lightly grease the O-ring and place it on the Speed  
Control. Install Valve Stem, O-ring (cleaned and lightly  
greased) and insert the Speed control into the Hous-  
ing in the midway position. Install the Retaining Ring.  
CAUTION: Make sure the Retaining Ring is completely  
snapped into groove in the Housing.  
3. Install the Valve Seat, the Valve and the Valve Spring.  
Coat the threads of the Bushing Assembly with 1 or 2  
drops of 3M Rite-Loc TL22 or equivalent non-permanent  
pipe thread sealant. Screw the assembly into the Hous-  
ing. Torque to 60 in/lbs (6.77 Nm.)  
A) For 5 and 6 in. (125 and 150 mm) machines:  
(1) Install the 5 or 6 in. (125 or 150 mm. ) Shroud or 6 in.  
(150 mm) Clean Sanding Shroud onto the Housing by  
working the shroud over and around the bottom of the  
housing flanges. Slide the inlet end of the Ø 1 in. (28  
mm) CV Swivel Exhaust Assembly or the Ø 3/4 in. (19  
mm) CV Swivel Exhaust Assembly into the exhaust port  
of the Shroud or Clean Sanding Shroud until it hits the  
stop on the Swivel Exhaust Assembly.  
NOTE: For installation of Shrouds and Skirts make sure the  
line up slots (on the Housing) and tabs (on the Shroud or  
Skirt) are engaged. Make sure that the key on the Swivel  
Exhaust Assembly bracket is aligned and engaged with the  
keyway on the Housing.  
B) Place the Washer over the Screw. Thread the screw  
T-1B  
Bearing  
Press Tool Top  
Shim  
Washer  
Press Tool Base  
Spindle  
T-1A  
34-8700-5191-8  
3
Revision 10/03/07  
 
into the mounting hole of the Swivel Exhaust Assembly  
and Housing until the end of the screw is flush with the  
inside surface of the Housing. Place the Nut into the  
cavity of the Housing and thread the Screw into the Nut  
until tight. Move onto the “Spindle, bearing shield and  
Shaft Balancer Assembly” Section.  
plate onto the Bearing using the larger end of the T-13  
Bearing Press Sleeve until the Front Bearing is seated  
in the bearing pocket of the Endplate. CAUTION: Only  
press just enough to seat the bearing into the pocket.  
Over-pressing can damage the bearing.  
3. Place the Key into the groove on the Shaft Balancer.  
Place the Rotor on the Shaft Balancer, making sure that  
it is a tight slip fit.  
4. Oil the five Vanes with a quality pneumatic tool oil and  
place them in the slots of the Rotor. Place the Cylinder  
Assembly over the Rotor with the short end of the  
Spring Pin engaging the blind hole in the Front End-  
plate. NOTE: The Spring Pin must project .060 in. (1.5  
mm) above the flanged side of the Cylinder.  
III. This section for SGV Exhaust machines:  
A) Install the Shroud or SGV Vacuum Skirt onto the Hous-  
ing by working the shroud or skirt over and around the  
bottom of the housing flanges. Make sure the line up  
slots (on the Housing) and tabs (on the Shroud or Skirt)  
are engaged.  
B) Attach the SGV Skirt Adapter or SGV Shroud Adapter to  
the exhaust port of the Shroud or SGV Skirt.  
C) Clean and lightly grease the two O-rings and place them  
in the two grooves in the SGV Retainer.  
5. Press fit the rear Bearing (2 shields) into the Rear  
Endplate with the T-1B Bearing Press Tool. Make sure  
the T-1B Press Tool is centered on the O.D. of the outer  
race. Lightly press fit the Rear Endplate and Bearing  
Assembly over the Shaft Balancer using the small end  
of the T-13 Bearing Press Sleeve. The sleeve should  
press only the inner race of the bearing. IMPORTANT:  
The Rear Endplate and Bearing Assembly is pressed  
correctly when the Cylinder is squeezed just enough  
between the Endplates to stop it from moving freely  
under its own weight when the shaft is held horizontal,  
but be able to slide between the Endplates with a very  
light force. If the assembly is pressed to tightly the  
motor will not run freely. If the pressed assembly is to  
loose, the motor will not turn freely after assembly in the  
Housing. Secure the assembly by placing the Retaining  
Ring in the groove of the Shaft Balancer. CAUTION: The  
Retaining Ring must be placed so that the middle and  
two ends of the hoop touch the Bearing first. Both raised  
center portions must be securely “snapped” into the  
groove in the Shaft Balancer by pushing on the curved  
portions with a small screwdriver.  
D) Put the SGV Retainer into the mounting hole of the Ø 1  
in. (28 mm) Hose SGV Swivel Exhaust Assembly.  
E) Push the Ø 1 in. (28 mm) Hose SGV Swivel Exhaust  
Assembly into the exhaust port of the SGV Skirt Adapter  
or SGV Shroud Adapter. Screw the SGV Retainer into  
the threaded exhaust port on the Housing with an 8 mm  
Hex Wrench. Torque to 45 in/lbs (5.08 Nm. ).  
Spindle, Bearing Shield and Shaft Balancer Assembly:  
1. Place the Washer and Shim on the Spindle shaft with  
the curve of the Washer facing up so that the outside  
diameter of the washer will contact the outer diameter of  
the Bearing. Place the Bearing on the Spindle with the  
seal side toward the Washer. Press onto Spindle using  
the T-1B Spindle Bearing Press Tool (see figure) until  
seated at bottom.  
2. Insert Shim with tangs into the bottom of Spindle Bore  
of the Shaft Balancer. (Do not use this shim if Shaft  
Balancer text shows a + symbol.)  
3. When the Spindle Assembly is done correctly, the Bearing  
will rotate freely but not loosely.  
4. Take the new Filter and center it on the small bore that  
the original Filter was in before removal. With a small  
diameter screwdriver or flat-ended rod, press the Filter  
into the bore until it is flat in the bottom of the bore.  
Place the Valve into the bore so it is oriented correctly,  
then press the Retainer into the bore until it is flush with  
the bottom of the Bearing bore.  
5. Apply a pin head size drop of 3M Rite-Loc TL71 or  
equivalent to the outside diameter of each of the bear-  
ings on the spindle assembly. Spread the drop of bear-  
ing locker around the bearing until distributed evenly.  
CAUTION: Only a very small amount of bearing locker  
is needed to prevent rotation of the bearing OD. Any ex-  
cess will make future removal difficult. Place the Spindle  
Assembly into the bore of the Shaft Balancer and secure  
with the Retaining Ring. CAUTION: Make sure that the  
Retaining Ring is completely snapped into the groove in  
the Balancer Shaft. Allow the adhesive to cure.  
6. Lightly grease the O-Ring and place in the air inlet of the  
Cylinder Assembly.  
7. Lightly grease or oil the inside diameter of the Housing,  
line up the Spring Pin with the marking on the Housing  
and slide the Motor Assembly into the Housing. Make  
sure the Spring Pin engages the pocket in Housing.  
8. Carefully screw the Lock Ring into the Housing with the  
T-6 Motor Lock Ring Wrench/Spindle Puller Tool. Torque  
to 60 in/lbs (6.77 Nm.) NOTE: A simple technique  
to assure first thread engagement is to turn the lock  
ring counter clockwise with the T-6 Motor Lock Ring  
Wrench/Spindle Puller while applying light pressure. You  
will hear and feel a click when the lead thread of the lock  
ring drops into the lead thread of the housing.  
9. Spin on a new Pad and hand tighten it using a 24 mm  
Pad Wrench.  
Testing:  
Place 3 drops of quality pneumatic air tool oil directly into  
the motor inlet and connect it to a 90 psig (6.2 bar) air  
supply. A 12,000 RPM tool should run between 11,500 to  
12,000 RPM when the air pressure is 90 psig (6.2 bar) at  
the inlet of the tool while the tool is running at free speed.  
This free speed will be about 500 RPM to 1,000 RPM less  
when a Vacuum or Hook Face Pad is used because of wind  
resistance. This will not affect performance when sanding.  
Motor Assembly:  
1. Use the larger end of the T-13 Bearing Press Sleeve to  
press the front Bearing (with 2 Shields) onto the shaft of  
the Shaft Balancer.  
2. Slide the Front Endplate with the bearing pocket facing  
down onto the Motor Shaft. Gently press the Front End-  
34-8700-5191-8  
4
Revision 10/03/07  
 
Troubleshooting Guide  
Symptom  
Possible Cause  
Solution  
Check air line pressure at the Inlet of  
the Sander while the tool is running at  
free speed. It must be 90 psig (6.2 Bar).  
Insufficient Air Pressure  
See the “Housing Disassembly” section  
for Muffler removal. The Muffler can  
be back flushed with a clean, suitable  
cleaning solution until all contaminates  
and obstructions have been removed. If  
the Muffler can not be properly cleaned  
then replace it. Replace Muffler Insert  
(See the  
Clogged Muffler(s)  
“Housing Assembly” Section).  
Clean the Inlet Screen with a clean,  
suitable cleaning solution. If Screen  
does not come clean replace it.  
Plugged Inlet Screen  
Install a complete set of new Vanes  
(all vanes must be replaced for proper  
operation). Coat all vanes with quality  
pneumatic tool oil. See “Motor Disas-  
sembly” and  
Low Power and/or Low Free Speed  
One or more Worn or Broken Vanes  
“Motor Assembly”.  
Check for proper Motor alignment and  
Lock Ring engagement. Check for  
damaged O-Ring in Lock Ring groove.  
Remove Motor Assembly and Re-Install  
the Motor Assembly. See “Motor Disas-  
sembly” and “Motor Assembly”.  
Internal air leakage in the Motor Housing  
indicated by higher than normal air con-  
sumption and lower than normal speed.  
Overhaul Motor. Contact authorized  
Service Center.  
Motor Parts Worn  
Replace the worn or broken Bearings.  
See “Shaft Balancer and Spindle Disas-  
sembly” and “Spindle Bearings, Bearing  
Shield and Shaft Balancer Assembly”.  
Worn or broken Spindle Bearings  
Disassemble, inspect and replace worn  
Air leakage through the Speed  
Control and/or Valve Stem.  
Dirty, broken or bent Valve Spring, Valve or damaged parts. See Steps 2 and 3  
or Valve Seat.  
in “Housing Disassembly” and Steps 2  
and 3 in “Housing Assembly”.  
Only use Pad Sizes and Weights  
designed for the machine.  
Incorrect Pad  
Only use abrasive and/or interface  
designed for the machine. Do not at-  
Addition of interface pad or other material tach anything to the Sanders Pad face  
that was not specifically designed to be  
used with the Pad and Sander.  
Disassemble the Sander and clean in  
Improper lubrication or buildup of foreign  
a suitable cleaning solution. Assemble  
debris.  
Vibration/Rough Operation  
the Sander.  
Replace the worn or broken Bearings.  
Worn or broken Rear or Front Motor  
See “Motor Disassembly” and “Motor  
Bearing(s)  
Assembly”.  
For SGV machines add extra washer(s)  
For vacuum machines it is possible to  
to the pad spindle to increase the gap  
have too much vacuum while sanding on between the pad and shroud. For CV  
a flat surface causing the pad to stick to  
machines reduce vacuum through  
the vacuum system and/or add extra  
washer(s) to the pad.  
the sanding surface.  
34-8700-5191-8  
5
Revision 10/03/07  
 

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