8
DISASSEMBLY INSTRUCTIONS
Changing Grips:
1. The (17) Grip has two “tabs” that wrap around the body of the
sander under the inlet and exhaust. Use a small screwdriver
to pick out one of the “tabs” of the Grip, and then continue to
go underneath the Grip with the screwdriver and pry the Grip
off the sander. To install a new grip, hold the Grip by the tabs
making them face outward, align the Grip and slide it under
the (15) Throttle Lever then press the Grip down until it seats
onto the top of the sander. Make sure the two “tabs” seat
under the inlet and exhaust..
Motor Disassembly:
1a. For 2.5mm orbit machines:
Lightly secure the tool in a vise
using the (MPA0026) T-7 Service Collar or padded jaws. Use
a (38) 17 mm Pad Wrench to secure the (39) Spindle and
spin the (40) Pad counter clock-wise off the spindle.
1b. For 5.0mm orbit machines:
Lightly secure the tool in a vise
using the (MPA0026) T-7 Service Collar or padded jaws to
secure the (44) Spindle and spin the (45) Pad counter clock-
wise off the spindle.
2. Remove the (12) Lock Ring with the (MPA0025) T-6 Motor
Lock Ring Wrench/Spindle Puller Tool. The motor assembly
can now be lifted out of the (19) Housing. Remove the (11)
O-Ring from the Lock Ring.
3. Remove the (1) Retaining Ring from the end of the (14 or 42)
Motor Shaft / Shaft Balancer and the (5) O-Ring from the (4)
Cylinder.
4. Remove the (3) Rear Endplate. This may require supporting
the Rear Endplate with a (MPA0416) Bearing Separator.
Use a light press force to push the (14 or 42) Motor Shaft /
Shaft Balancer through the (10) Bearing. Then remove the
(4) Cylinder, (7) Vanes and the Rotor. Remove the (8) Key
from the Motor Shaft / Shaft Balancer . Support the (9) Front
Endplate with a Bearing Separator and use a light press force
to push the Motor Shaft / Shaft Balancer through the Bearing.
It may be necessary to remove the Bearing with a Bearing
Separator if it came out of the Front Endplate and stuck to the
shaft of the Motor Shaft / Shaft Balancer .
5. Remove and discard (41) Dust shield from the (14) Motor
Shaft or (42) Shaft Balancer.
6. Remove the Bearing(s) from the Endplates by using the
(MPA0036) T-8 End Plate Bearing Removal Tool to press out
the Bearings.
Mini Random Orbital Head Disassembly(2.5mm Orbit):
1. Hold the (39) Spindle Assembly in a fixed position by using
the (38) 17 mm Wrench. Remove the set screw from the
Spindle Assembly using a 1/8 in. Hex Key.
2. With a small, thin-tipped flathead screwdriver pick-out the
slotted end of the (37) Retaining Ring, then continue to peel-
out the retaining ring all the way around until it is free from
the groove in the (31) Mini Random Orbital Head. Screw the
female end of the (MPA0271) T-11 5/16-24 to 1/4-20 Adapter
into the male end of the (MPA0025) T-6 Motor Lock Ring
Wrench/Spindle Puller Service Tool. Screw the (MPA0025)
T-6 Motor Lock Ring Wrench/Spindle Puller Service Tool
assembly into the (39) Spindle Assembly until hand tight.
Remove the Spindle Assembly from the Mini Random Orbital
Head by using the Slider to give sharp outward blows to the
Spindle Assembly.
3. Remove the (32) Retaining Ring from the (39) Spindle As-
sembly.
4. Place the (39) Spindle Assembly into a bearing separator and
press off the (33) Bearing, (34) Spacer, (35) Bearing, (43)
Shim and the (36) Washer.
Shaft Balancer and Spindle Disassembly(5.0mm Orbit):
1. Grip the shaft end of the (42) Shaft Balancer in a padded
vise. With a thin screwdriver pick out the slotted end of
the(37) Retaining Ring and peel out.
2. Screw the female end of the (MPA0101) T-12 5/16-24 to 6mm
Adapter into the male end of the (MPA0025) Service Wrench.
Screw the Service Wrench assembly into the (44) Spindle
Assembly until hand tight. Apply a gentle heat from a propane
torch or hot air gun to the large end of the (42) Shaft Balancer
until it is about 100° C (212° F) to soften the adhesive. Do not
over heat. Remove the Spindle Assembly by using the Slider
to give sharp outward blows to the Spindle. Allow the parts to
cool so they are safe to handle.
3. Remove the (32) Retaining Ring from the (44) Spindle As-
sembly. Use a small Bearing Separator to remove the (33)
Bearing, (34) Spacer, (35) Bearing, (43) Shim
and the (36)
Washer from the Spindle Assembly.
Housing Disassembly:
1. Place the (29) Speed Control to the midway position and re-
move the (30) Retaining Ring with lock ring pliers. The Speed
Control will now pull straight out. Remove the (28) O-Ring.
2. Unscrew the (26) Inlet Bushing Assembly from the (19) Hous-
ing. Remove the (25) Spring, (24) Valve, (23) Seat and the
(27) Valve Stem.
3. Press out the (16) Spring Pin from the (19) Housing and
remove the (15) Throttle Lever then press out the (18) Sleeve
in either direction.
4. Unscrew the (22) Muffler Housing (using a 21mm wrench)
from the (19) Housing.
5. Remove the (20) Muffler from the (22) Muffler Housing and
remove the (21) Muffler insert.
ASSEMBLY INSTRUCTIONS
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. Press the (18) Sleeve into the (19) Housing flush with the top
from the (15) Throttle Lever side. Install Throttle Lever into (19)
Housing with (16) Spring Pin.
2. Lightly grease the (28) O-Ring and place it into the groove in
the (29) Speed Control. Install the (27) Valve Stem and O-Ring
(cleaned and lightly greased) and insert the Speed Control
into (19) Housing in the midway position. Install (30) Retaining
Ring. Caution: Make sure the Retaining Ring is completely
snapped into groove in the Housing.
3. Install the (23) Seat, (24) Valve and the (25) Spring. Coat the
threads of the (26) Bushing Assembly with 1 or 2 drops of
Loctite™ 222 or equivalent non-permanent pipe thread sealant.
Screw the Bushing Assembly into the inlet port on the (19)
Housing until hand tight. For torque settings go to the Section
“Parts Page”.
Mini Random Orbital Head Assembly(2.5mm Orbit):
1. Hold the (39) Spindle Assembly in a fixed position by using
the (38) 17 mm Wrench. Install the Set Screw into the Spindle
Assembly using a 1/8 in. Hex Key.
2. Place the (MPA0207) T-4A Spindle Bearing Pressing Tool Base
onto a flat, clean surface of a small hand press or equivalent
with the spindle pocket facing upward. Place the (39) Spindle
MIRKA 8,000 RPM
32 mm (1
1
/
4
in.)
RANDOM ORBITAL SANDER
SERVICE INSTRUCTIONS
NOTICE: To receive any expressed or implied warranty, tool must be repaired by an authorized Mirka Service Center. The following
general service instructions provided are for use after completion of the warranty period.
