Complete Teardown, Cleaning, and Reassembly of the Olympus BH-2 Coaxial Focus Mechanism Revision 4 Page 38 of 40
Appendix 1
A Caution Regarding the Plastic Gears in the Olympus BH-2
Shipping Damage to BH-2 Microscope Stands
The Achilles heel of the BH-2 microscope stand is the
small plastic gear pressed into the underside of the
right-hand fine-focus knob (see Figure 120). This gear
was made of plastic so as to act as a sacrificial
component, preventing careless operators from causing
major damage to the mechanical components in the
focus mechanism. Figure 121 shows the knob with this
gear pressed in and with the fine-focus shaft installed.
Figure 120 – Plastic gear in the back of fine-focus knob
Figure 121 – The fine-focus shaft and plastic gear in knob
This inherently fragile plastic gear, which is no longer
available from Olympus, very frequently sustains
damage during shipping when these microscope stands
have been packaged incorrectly. To prevent such
damage, BH-2 stands must be packaged such that the
normal shocks which occur during routine shipping do
not produce significant stresses on this gear, otherwise
damage to this gear can, and very frequently does,
occur. Figure 122 shows an example of what can
happen to this fragile gear during shipping when the
proper packaging guidelines have not been followed.
Experience has shown that as many as 10-20% of all
BH-2 stands which are shipped with improper
preparation and packaging will be damaged in this way.
Figure 122 – A fine-focus gear damaged during shipping
In addition to breakage of the sacrificial gear in the fine-
focus knob, shipping shocks can also damage the brass
focus rack mounted onto the back side of the sliding
focus block (see Figure 123), as well as the gear in the
focus gearbox that meshes with this rack. The teeth on
these parts may be deformed, or in extreme cases,
sheared off entirely, as a result of shocks to the shipping
container. And of course, these parts also are no longer
available from Olympus.
Figure 123 – The brass focus rack
Preparing BH-2 Stands for Shipping
To prevent the sort of damage described above, it is
critical that all BH-2 stands be properly prepared and
packaged prior to shipment. Refer to the document
Successfully Shipping Olympus BH-2 Microscopes for
details of how to protect BH-2 microscopes from
shipping damage.
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