Complete Teardown, Cleaning/Lubrication, and Reassembly of the Olympus BH2-CH Substage Assembly
Revision 1 Page 6 of 26
Introduction
The microscopes in the Olympus BH-2 line (BHS, BHSU,
BHT, and BHTU) have largely been replaced in the
professional and clinical world, due to their advancing
age and the lack of repair parts from Olympus. A great
many of these microscopes were produced in their day,
and because of this are they readily available on the
used market for very reasonable prices. Thanks to their
excellent build quality and solid optical performance,
these scopes are now very popular with hobbyists,
providing an affordable, high-quality alternative to the
Chinese-made scopes prevalent today.
The BH2-CH substage assembly (sometimes referred to
as the
Condenser Holder
) on the BH-2 equipment
mounts onto the sliding focus block of the stand, and
provides a ring for the mechanical stage to mount onto,
as well as a centering mount for the substage
condenser. The height of the substage condenser can
be adjusted, relative to the stage, by a rack-and-pinion
mechanism, and the maximum condenser height can be
precisely set by the adjustable condenser-height stop.
Due to the age of BH-2 equipment, the BH2-CH
substage assembly frequently needs disassembled and
regreased to function well again.
Scope of this Document
This document describes the complete teardown,
cleaning/lubrication, and reassembly of the BH2-CH
substage assembly used on the Olympus BH-2 series of
microscopes.
Tools Needed
The following tools are needed to service the BH2-CH
substage assembly:
Allen wrench or driver, 1.5mm (item 4 of
Allen wrench or driver, 2.5mm (item 5 of
Allen wrench or driver, 3.0mm (item 6 of
Center punch (or nailset)
Pliers, needle-nose (fine-point)
Screwdriver set, JIS (item 7 of
Screwdriver set, slotted
A Few Words about JIS Screws
Screws with JIS heads are found in much of the
equipment designed and manufactured in Japan. JIS
screws look very much like standard Phillips screws, but
they differ in that JIS screws were designed to not cam-
out under torque, whereas Phillips screws were
designed to intentionally cam-out, as a means to limit
the torque applied to the fasteners. Because of this
crucial difference in the geometry of the two screw
types, JIS screws will be damaged by standard Phillips
drivers if too much torque is applied. JIS screws can
usually be identified by the presence of a single dot, or
by an “X”, stamped into one of the four quadrants of
the cross-point depression (see
Figure 1 – Head of a typical JIS screw
Supplies Needed
The following supplies are needed to service the
BH2-CH substage assembly:
Cleaning solvent (see
Cotton swabs
Grease (see
Tissues, oil-free
Recommended Lubricants
Dow Molykote® 44 (item 2 of
) or Nye 704C
(item 3 of
) is recommended for the BH2-CH
substage assembly. Both of these greases are
sufficiently light for the greased dovetail slides, and
both types will remain stable and serviceable for many
years to come.
Recommended Solvents
Some type of cleaning solvent will be needed to remove
the old grease from the various components of the
BH2-CH substage assembly. Solvents that can be used
are acetone, diethyl ether, heptane, hexane, mineral
spirits, turpentine, and xylene.
Safety Considerations with Solvents
Regardless of which solvent is chosen, make sure that
adequate ventilation is present during the cleaning
process, and that any necessary personal protective
equipment is utilized to minimize exposure. Consult the
MSDS sheet before using any unfamiliar solvents. Many
of the solvents listed above are flammable, and their
vapors may represent an explosion hazard if
mishandled. Whichever solvents are chosen, be sure to
follow all manufacturer’s instructions and safety
precautions.
Solvent Compatibility with Parts and Finishes
Many solvents will damage the finish of painted
surfaces (isopropyl alcohol or 409 Cleaner may be safely
