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Motor Assembly/Disassembly Instructions – Dynabug Orbital Sander

Important:  Manufacturer’s warranty is void if tool is disassembled before warranty expires.

A Motor Repair Kit (57098) is available which contains special tools for disassembly/assembly. Please refer to parts breakdown for part identification.

To Disassemble:

1.

Disconnect tool from power source.  Invert machine and secure in vice, using 

57092 

Collar (supplied in 

57098 

Repair Kit) or padded jaws.

2.

Disconnect sanding pad by removing 

96258 

Screws (4) with a 3 mm wrench.

3.

With a Phillips head screw driver remove 

96114 

Screws (6).  Remove 

96168 

Screw with 3/16" hex wrench, and remove pad top from boot.

4.

Disengage 

96116 

Clamp by using a screwdriver to unscrew clamp.  Remove clamp, 

57822 

Boot and 

57823 

Pad Mount from housing.

5.

Insert 

56058 

Lock Ring Tool (supplied in 

57098 

Repair Kit) into corresponding tabs of lock ring and unscrew.  Motor may now be lifted out for service.

6.

Remove rear ring from motor.  Upper motor may now be disassembled.  Remove 

95626 

Snap Ring.

7

Remove the rear plate and the cylinder assembly by securing the cylinder in a bearing separator gripped on the cylinder exhaust and extra pocket area.
Push the motor shaft balancer through the bearing.  

8.

Remove the rotor, vanes and rotor key from the motor shaft balancer.  Remove the front plate using a (#2) arbor press.  Support the edges of the
front plate while pressing on the small end of the motor shaft balancer.

9. a.)

If, during step 9, the front plate and bearing remain together, press bearing out of the front plate using 

57091 

Press Tool (supplied in 

57098

Repair Kit).

b.)

If, during step 9, the front plate and 

57088 

Bearing remains on the motor shaft balancer, it can be removed with a bearing separator.

11.

Remove 

01206 

Bearing from the rear plate by using a bearing press tool.  Remove lock ring, washer and front ring.

12.

Disassemble the balancer assembly as follows:

a.)

Place motor shaft assembly into a soft jaw vise.  Using a thin screwdriver, pick out the end of 

95630 

Snap Ring and peel out.

b.)

Screw the threaded portion of the 

56056 

Bearing Puller (supplied in 

57098 

Repair Kit) into the 

57069 

Balancer Shaft and heat the outside of the 

motor shaft balancer to approximately 200° F (approximately 10 seconds with a propane torch).  Now, using the slider weight, pull the assembly out.

c.)

Press off 

56052 

Bearing with a bearing separator and remove bearing seal and bearing shield.

13.

If during step 12, the 

56052 

Bearing remains in the motor shaft balancer, it can be removed by heating the shaft balancer again and using either an 

inside bearing puller or a blind hole bearing puller.

Tool disassembly complete.

To Assemble

Important:

Be certain parts are clean and in good repair before assembling.

1.

Assemble the balancer assembly as follows: 

a.)

Install 

95630 

Snap Ring onto 

57069 

Balancer Shaft.  Install 

95628 

Shield with convex face toward hex of balancer shaft.  Install 

56053 

Seal. 

Note: 

Be certain seal is pressed completely over shaft step.

b.)

Apply 1 drop of #271 Loctite

®

(or equivalent) and spread over several places around the inside diameter of the 

56052 

Bearing and the outside 

diameter of the 

57069 

Balancer Shaft.

c.)

Press fit 

56052 

Bearing with seal side toward hex of balancer shaft up to shaft step.  This must be a firm press fit for proper retention of bearing.

2.

Place the motor shaft balancer in a soft jaw vise with large end-up.

3.

Apply 1 drop of #271 Loctite

®

(or equivalent) and spread over several places around the outside diameter of the 

56052 

Bearing and slide balancer

assembly into the motor shaft balancer until 

56052 

Bearing is firmly seated at bottom.  Squeeze 

95630 

Snap Ring into groove in motor shaft balancer to

complete the assembly.  Remove from vise.

4.

Press 

57088 

Bearing onto the motor shaft balancer down to the shoulder.  Place lock ring, washer and front ring on motor shaft balancer.

5.

Press 

57057 

Front Bearing Plate onto 

57088 

Bearing and check for smooth rotation.

6.

Place the 

57090 

Rotor and 

56047 

Rotor Key on the motor shaft balancer.  Place the 

56073 

Vanes into the rotor slots.

Note:  

Vanes should be lightly lubricated with Dynabrade Air Lube P/N 

95842 

(or equivalent) before installation into the rotor slots.

7.

Place 

57058 

Cylinder Assembly over rotor.  The “short” line-up pin goes toward the front plate.

8.

Place 

57056 

Rear Bearing Plate (with rear bearing pressed into place) over shaft and “long” end of line-up pin and press fit in place

Insert

95626 

Snap Ring.

9.

Place 

57054 

Rear Ring over the rear plate and line-up pin.  Make sure that the “legs and fingers” on the front and rear rings line-up.

10.

Secure motor housing in vise, using 

57092 

Collar or padded jaws.  Spread 2-3 drops of pneumatic tool oil around the housing bore and slide motor 

assembly in housing.  

Note:

Be certain line-up pin enters the pocket in bottom of the housing and the “legs” of the rings stay in line. 

11.

Tighten lock ring with 

56058 

Lock Ring Tool torque to 28 N•m/250 in. - lbs.

12.

Insert 

57823 

Pad Mount into boot.  Attach boot to housing with exhaust hole facing back and slide clamp over boot.   

13.

Place 

57837 

Washer into hex pocket with shoulder down.  Line-up holes in pad top with holes in boot and secure with 

96114 

Screws (6).

14.

Secure pad top and boot to motor assembly by installing 

57838 

Washer, 

95183 

Washer and 

96168 

Screw through pad top and into balancer shaft.

15.

Position pad top to desired angle and tighten clamp to 0.7 N•m/6 in. - lbs. so that the top of the clamp is even with the top of the boot.

16.

Attach sanding pad by installing 

96258 

Screws (4).

Valve and Speed Regulator Assemblies:

1.

Secure housing in vice using 

57092 

Collar or padded jaws.  Remove inlet bushing, 

01468 

Spring, 

01472

Tip Valve and 

01464

Seal from housing.

2.

Remove 

95697 

Snap Ring.  Press the speed regulator and valve stem out of the housing.  Remove the 

01025 

O-Rings (2).

3.

Place new 

01025 

O-Rings (2) on the speed regulator and place in housing with valve stem.  Install new 

95967 

Snap Ring.

4.

Place seal in housing.  Using tweezers or needle nose pliers, place the tip valve in the housing so that its pin goes into the valve stem hole.  Place 

01468

Spring into the housing so the small end is toward the tip valve.

5.

Spread one drop of #567 Loctite

®

(or equivalent) around the first threads of the first inlet bushing and tighten into housing torque to 23 N•m/200 in. - lbs.

Tool assembly is complete.  Please allow 30 minutes for adhesives to cure before operating tool. 

Loctite

®

is a registered trademark of the Loctite Corp.

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