Complete Teardown, Cleaning, and Reassembly of the Olympus BH-2 Coaxial Focus Mechanism Revision 4 Page 31 of 40
Reach around to the front of the pillar arm and raise the
sliding focus block to gain access to the lower screw
hole in the brass focus rack. While holding the sliding
focus block in this position, use a 2.5mm Allen tool or
driver to reinstall and tighten the lower M3X8 hex
socket-head cap screw (see Figure 95). Lower the
sliding focus block back to its lowest position and
tighten the upper screw.
Figure 95 – Reinstall the lower screw for the focus rack
Grease the Brass Focus Rack (Optional)
Note: This step is optional and may be omitted if the
equipment will be used in an environment where debris
might accumulate on a greased focus rack, which would
foul the rack-and-pinion focus block mechanism.
Apply fresh grease to the teeth of the brass focus rack,
manipulating the sliding focus block as necessary to
expose the face of the rack to facilitate the application.
Make sure that the entire face of the brass focus rack is
covered with greased (see Figure 96).
Figure 96 – Grease the teeth of the focus rack (optional)
Disassemble the Focus Gearbox
The focus gearbox must be fully disassembled so that
the old grease can be thoroughly removed from the
various components of the focus gearbox. To
disassemble the focus gearbox, first rotate the gears
until the two hex-head setscrews are accessible. If the
gears cannot be freely rotated due to thickened grease
in the gearbox, use a heat gun to heat the entire focus
gearbox, or apply a drop of a suitable penetrating oil to
both ends of the two gear pins, which should loosen the
old grease enough to allow the gears to rotate. Once
the heads of the setscrews are accessible, use a 1.3mm
Allen tool or driver to remove the two M2.6X4
setscrews securing the gears to the gear pins (see
Figure 97).
Figure 97 – Remove two setscrews securing the gears
After the setscrews securing the gears to the gear pins
have been removed, use the tip of a screwdriver (or
similar blunt tool) to press the two gear pins free of the
focus gearbox housing (see Figure 98). If necessary, use
a heat gun to heat the gearbox, or use a suitable
penetrating oil, to loosen the old grease enough to
allow the gear pins to be pressed out. Once the gear
pins have been pressed out of the gearbox housing,
remove the two loose gears and the four nylon thrust
washers that were present at the ends of the two gears.
Figure 98 – Press both gear pins free of the housing
The various components of the fully disassembled focus
gearbox can be seen in the Figure 99.
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