Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 1 of 18
Complete Teardown, Cleaning, and
Reassembly of the Olympus BHTU
Reverse Nosepiece Assembly
Revision 2
Copyright © 2017, 2018 Carl Hunsinger
All rights reserved. This document may not be reproduced or distributed, in whole or in part, for any commercial
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The content of this document is provided for informational purposes only, with no expressed or implied warranties
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Revision History
Revision
Description of Changes
Date
1
*** Initial release ***
June 1, 2017
2
Revised images and content to make common with BH2-5RE assembly.
June 29, 2018
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 2 of 18
Table of Contents
Introduction ............................................................................................................................................................................ 5
Scope of this Document .......................................................................................................................................................... 5
Tools and Supplies Needed ..................................................................................................................................................... 5
Recommended Lubricant Types .............................................................................................................................................. 5
Recommended Solvents ......................................................................................................................................................... 5
Remove the Objectives from the Nosepiece .......................................................................................................................... 5
Label Parts for Identification and Reassembly ........................................................................................................................ 5
The Reverse Nosepiece Assembly ........................................................................................................................................... 5
Remove the Reverse Nosepiece Assembly ............................................................................................................................. 6
Remove Corrective Optics and Wedge Mount ....................................................................................................................... 6
Remove the Cover from the Turret Assembly ........................................................................................................................ 7
Remove Lock Ring for Pivot-Adjustment Screw ...................................................................................................................... 8
Remove the Pivot-Adjustment Screw ..................................................................................................................................... 9
Remove the Center-Pivot Bearing Ball .................................................................................................................................... 9
Remove the Mechanical Detent Stop ..................................................................................................................................... 9
Remove the Black Knurled-Rubber Grip Ring ....................................................................................................................... 10
Remove the Threaded Retaining Ring .................................................................................................................................. 10
Remove the Perimeter Bearing Balls .................................................................................................................................... 10
Remove the Stationary Base from the Turret ....................................................................................................................... 11
Clean Grease from the Various Components ....................................................................................................................... 11
Reinstall Stationary Base into Revolving Turret .................................................................................................................... 11
Apply Ring of Grease for the Perimeter Balls ....................................................................................................................... 11
Reinstall the Perimeter Bearing Balls .................................................................................................................................... 11
Reinstall the Threaded Retaining Ring .................................................................................................................................. 12
Apply Grease to the Center-Pivot Bore ................................................................................................................................. 12
Reinstall the Center-Pivot Bearing Ball ................................................................................................................................. 12
Apply Grease to Top of the Center-Pivot Ball ....................................................................................................................... 13
Reinstall the Pivot-Adjustment Screw .................................................................................................................................. 13
Reinstall the Slotted Lock Ring .............................................................................................................................................. 13
Verify the Feel of the Revolving Nosepiece .......................................................................................................................... 13
Clean Off Any Visible Grease ................................................................................................................................................. 14
Reinstall the Mechanical Detent Stop................................................................................................................................... 14
Apply Grease to the Mechanical Detents ............................................................................................................................. 14
Reinstall the Protective Cover ............................................................................................................................................... 14
Reinstall the Knurled-Rubber Grip Ring ................................................................................................................................ 15
Reinstall Wedge Mount and Corrective Optics ..................................................................................................................... 15
Reinstall the Reverse Nosepiece Assembly........................................................................................................................... 16
Ready for Service .................................................................................................................................................................. 17
Requirements for Periodic Maintenance .............................................................................................................................. 17
Problems with the Turret Assembly ..................................................................................................................................... 17
A Few Words about JIS Screws ............................................................................................................................................. 17
Original Olympus Documentation ........................................................................................................................................ 17
Appendix 1 ............................................................................................................................................................................ 18
How to Contact the Author ................................................................................................................................................... 18
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 3 of 18
Table of Figures
Figure 1 – The BHSU / BHTU reverse nosepiece assembly ..................................................................................................... 6
Figure 2 – Screws securing reverse nosepiece assembly ........................................................................................................ 6
Figure 3 – Remove screws securing nosepiece assembly ....................................................................................................... 6
Figure 4 – Screws securing the wedge mount ........................................................................................................................ 6
Figure 5 – Remove screws securing the wedge mount .......................................................................................................... 7
Figure 6 – Loosen the corrective optics assembly .................................................................................................................. 7
Figure 7 – Remove the corrective-optics assembly ................................................................................................................ 7
Figure 8 – Remove the wedge mount ..................................................................................................................................... 7
Figure 9 – Remove screws securing the cover in place .......................................................................................................... 7
Figure 10 – Remove the protective cover ............................................................................................................................... 7
Figure 11 – The turret assembly (without cover) ................................................................................................................... 8
Figure 12 – Screwdriver modified to remove slotted lock ring .............................................................................................. 8
Figure 13 – Insert screwdriver into bores to lock the turret .................................................................................................. 8
Figure 14 – Loosen the slotted lock ring ................................................................................................................................. 8
Figure 15 – Remove the slotted lock ring ............................................................................................................................... 9
Figure 16 – Remove the pivot-adjustment screw ................................................................................................................... 9
Figure 17 – Remove the center-pivot bearing ball ................................................................................................................. 9
Figure 18 – Remove the screws securing the detent stop ...................................................................................................... 9
Figure 19 – Remove the mechanical detent stop ................................................................................................................. 10
Figure 20 – Remove the knurled-rubber grip ring ................................................................................................................ 10
Figure 21 – Components of the turret assembly .................................................................................................................. 10
Figure 22 – Loosen the threaded retaining ring ................................................................................................................... 10
Figure 23 – Remove the threaded retaining ring .................................................................................................................. 10
Figure 24 – Remove the perimeter bearing balls ................................................................................................................. 11
Figure 25 – Lift and remove the stationary base .................................................................................................................. 11
Figure 26 – Reinstall stationary base into revolving turret ................................................................................................... 11
Figure 27 – Apply ring of fresh grease for the bearing balls ................................................................................................. 11
Figure 28 – Place the bearing balls into the ring of grease ................................................................................................... 12
Figure 29 – Engage the threaded retaining ring ................................................................................................................... 12
Figure 30 – Tighten the threaded retaining ring ................................................................................................................... 12
Figure 31 – Remove any grease squeeze-out ....................................................................................................................... 12
Figure 32 – Apply grease to the center-pivot bore ............................................................................................................... 12
Figure 33 – Place bearing ball into the center-pivot bore .................................................................................................... 13
Figure 34 – Apply grease to the top of the bearing ball ....................................................................................................... 13
Figure 35 – Reinstall the pivot-adjustment screw ................................................................................................................ 13
Figure 36 – Reinstall the slotted lock ring ............................................................................................................................. 13
Figure 37 – Tighten the slotted lock ring .............................................................................................................................. 13
Figure 38 – Place the mechanical detent stop in position .................................................................................................... 14
Figure 39 – Secure the detent stop with two screws ........................................................................................................... 14
Figure 40 – Apply grease to the five detent notches ............................................................................................................ 14
Figure 41 – Place cover in position on the turret assembly .................................................................................................. 14
Figure 42 – Secure protective cover using three screws ...................................................................................................... 15
Figure 43 – Apply black silicone RTV to revolving turret ...................................................................................................... 15
Figure 44 – Reinstall the knurled-rubber grip ring ................................................................................................................ 15
Figure 45 – Remove any silicone RTV squeeze-out .............................................................................................................. 15
Figure 46 – Place the wedge mount in position ................................................................................................................... 15
Figure 47 – Reinstall the corrective-optics assembly ............................................................................................................ 16
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 4 of 18
Figure 48 – Reinstall screws to secure the wedge mount .................................................................................................... 16
Figure 49 – Tighten the corrective optics assembly ............................................................................................................. 16
Figure 50 – Hold reverse nosepiece assembly up to arm ..................................................................................................... 16
Figure 51 – Align holes for the mounting screws .................................................................................................................. 16
Figure 52 – Reinstall three screws to secure it to the arm ................................................................................................... 17
Figure 53 – A typical JIS Screw .............................................................................................................................................. 17
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 5 of 18
Introduction
The microscopes in the Olympus BH-2 line 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 they
are 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.
One issue that might be encountered when purchasing
either the BHSU or BHTU version of these microscopes
is that the grease in the reverse nosepiece assembly
may be dried and gummy, resulting in a stiff or gritty
feel of the revolving nosepiece.
Another issue that may be encountered is with the
mechanical detents in the revolving nosepiece. After
many years of hard service, especially if the nosepiece
assembly has not been periodically lubricated
throughout its life, one or more of the detent stops may
be worn to the point where the detents are sloppy and
the affected objectives do not maintain proper radial
indexing. At best, this is annoying to the operator, and
at worst can render the revolving nosepiece unusable.
This document describes the complete teardown,
cleaning, lubrication, and reassembly of the reverse
nosepiece assembly on a BHTU microscope stand.
Completion of this maintenance procedure should
restore the proper feel to the nosepiece turret.
Additionally, this maintenance should reduce further
wear of the mechanical detent stops. Note that if the
detents stops are already excessively worn, there is no
repair for this other than the replacement of the
revolving turret.
Scope of this Document
The procedures detailed in this document apply to the
reverse nosepiece assembly used on the Olympus BHSU
and BHTU microscope stands.
Note that the original Olympus service literature did not
address the teardown and repair of the various
revolving nosepiece assemblies used on BH-2 stands, as
these were field-replaceable assemblies that were
considered unserviceable by Olympus.
Tools and Supplies Needed
The following tools and supplies will be needed to
complete the teardown, cleaning, lubrication, and
reassembly of the BHSU/BHTU reverse nosepiece
assembly:
• Center punch or nailset tool
• Cleaning solvent (see recommendations below)
• Electric heat gun (item 1 of Appendix 1)
• Lens-spanner tool (item 6 of Appendix 1)
• Lubricant (see recommendations below)
• Screwdriver set, JIS (item 2 of Appendix 1)
• Silicone RTV adhesive, black (item 7 of Appendix 1)
• Soft-jaw pliers (item 5 of Appendix 1)
Recommended Lubricant Types
Plastilube® Brake Grease or Mobilith SHCTM 220
synthetic grease (item 8 of Appendix 1) are
recommended for use in the reverse nosepiece
assembly. Both Plastilube® Brake Grease and SHCTM
220 are medium-consistency greases which will remain
stable and serviceable for many years to come.
Recommended Solvents
Some sort of solvent will be needed to clean the old
grease from the components of the reverse nosepiece
assembly. Solvents that can be used are acetone,
diethyl ether, heptane, hexane, mineral spirits,
turpentine, and xylene. 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. Many solvents will damage
rubber or plastic parts, or the finish of painted surfaces.
Isopropyl alcohol or 409 Cleaner may be safely used to
clean most painted surfaces. Mineral spirits works well
with both Plastilube® and SHCTM 220 greases.
Remove the Objectives from the Nosepiece
Before beginning the removal and teardown of the
reverse nosepiece assembly, remove all the objectives
from the revolving turret and store them someplace
where they will be protected from physical damage,
dust, and debris.
Label Parts for Identification and Reassembly
During the teardown of the reverse nosepiece
assembly, be sure to bag and tag the various parts to
prevent their loss and to facilitate their proper
identification during reassembly.
The Reverse Nosepiece Assembly
The reverse nosepiece assembly used on the BHSU and
BHTU stands consists of a five-position turret assembly,
a wedge mount, and an accompanying corrective-optics
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 6 of 18
assembly. The turret assembly is the same one used on
the BH2-5RE revolving modular nosepiece assembly for
the BHS and BHT stands, but rather than utilizing a
machined dovetail slide to mount the turret assembly
onto the stand, the BHSU/BHTU version includes a
wedge mount to secure the turret assembly onto the
stand in reverse orientation, and a corrective-optics
assembly to correct for the difference in tube length
introduced with the incorporation of the wedge mount
(see Figure 1).
Figure 1 – The BHSU / BHTU reverse nosepiece assembly
Remove the Reverse Nosepiece Assembly
The reverse nosepiece assembly, which must be
removed from the arm as a complete assembly, is
secured to the top of the microscope arm by three
M2.6X14 pan-head screws (see Figure 2).
Figure 2 – Screws securing reverse nosepiece assembly
To remove the reverse nosepiece assembly, hold the
reverse nosepiece assembly in place with one hand and
use a suitable JIS screwdriver to remove the three
M2.6X14 pan-head screws securing it to the microscope
arm with the other hand (see Figure 3).
Figure 3 – Remove screws securing nosepiece assembly
Remove Corrective Optics and Wedge Mount
The wedge mount is attached to the stationary base of
the turret assembly with four M2.6X25 pan-head
screws, and by the corrective-optics assembly, whose
threaded end passes through the center bore of the
wedge mount and screws into the tapped center bore
of the stationary base (see Figure 4).
Figure 4 – Screws securing the wedge mount
Before attempting to loosen and remove the correctiveoptics assembly, use a suitable JIS screwdriver to
remove the four M2.6X25 pan-head screws securing the
wedge mount to the stationary base of the turret
assembly (see Figure 5). It is important to remove these
four screws before attempting to remove the
corrective-optics assembly, to prevent the barrel of the
corrective-optics assembly from binding with the center
bore in the wedge mount (due to the very close
tolerances involved) when the corrective-optics
assembly is loosened and removed.
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 7 of 18
Figure 5 – Remove screws securing the wedge mount
Once the four M2.6X25 pan-head screws securing the
wedge mount to the turret assembly have been
removed, use non-marring pliers or a suitable strap
wrench to grip the barrel of the corrective-optics
assembly and loosen the corrective-optics assembly by
rotating it counter-clockwise (see Figure 6).
Figure 6 – Loosen the corrective optics assembly
Unscrew and remove the corrective-optics assembly,
which at this point is all that is holding the wedge
mount onto the stationary base of the turret assembly
(see Figure 7). Once the corrective-optics assembly has
been removed, place it someplace where it will be
protected from physical damage, dust, and debris.
Figure 7 – Remove the corrective-optics assembly
Now that the four M2.6X25 pan-head screws and the
corrective-optics assembly have been removed, remove
the loose wedge mount from the turret assembly (see
Figure 8).
Figure 8 – Remove the wedge mount
Remove the Cover from the Turret Assembly
Use a suitable JIS screwdriver to remove the three
M2X3 countersink screws securing the protective cover
onto the stationary base (see Figure 9) and remove the
protective cover (see Figure 10).
Figure 9 – Remove screws securing the cover in place
Figure 10 – Remove the protective cover
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 8 of 18
Figure 11 – The turret assembly (without cover)
Remove Lock Ring for Pivot-Adjustment Screw
The slotted lock ring for the pivot-adjustment screw
(see Figure 11) can be difficult to remove unless the
proper tool is used. Do not attempt to remove the
slotted lock ring and pivot-adjustment screw unless you
have access to such a tool, since the slot in the lock ring
will likely be damaged if you use an improper tool,
making removal of the lock ring much more difficult1. A
suitable tool for this task can be easily made by filing or
grinding a relief notch for the pivot-adjustment screw in
the center of the blade of a large slotted screwdriver, as
shown in Figure 12. Note that if you decide to make
such a tool, be sure that the tip of the screwdriver you
select has a blade width matching the outer diameter of
the slotted lock ring, and that the thickness of the blade
is such that it will seat fully into the slot of the slotted
lock ring.
Figure 12 – Screwdriver modified to remove slotted lock ring
Prevent the Revolving Turret from Spinning
Before attempting to loosen the slotted lock ring, the
revolving turret must first be locked in position relative
1
Don’t even think about using a pair of needle-nose pliers to loosen
the slotted lock ring. It will end badly if you do this. Don’t ask me
how I know this.
to the stationary base, in order to allow for sufficient
torque to be applied to the slotted lock ring to loosen
and remove it. To lock the position of the revolving
turret, first spin the revolving turret until the bore in the
stationary base aligns with one of the five threaded
objective bores in the revolving turret. While holding
the turret such that these two bores remain aligned,
insert a small screwdriver handle of the appropriate size
into the two bores (see Figure 13). This will prevent the
revolving turret from moving relative to the stationary
base when torque is applied to loosen the slotted lock
ring. The handle of the screwdriver should safely
prevent the turret from spinning, without causing any
damage to the fragile brass threads in the revolving
turret.
Figure 13 – Insert screwdriver into bores to lock the turret
Loosen and Remove the Slotted Lock Ring
Hold the turret assembly by grasping the knurledrubber grip ring on the outer perimeter of the revolving
turret and use the slotted screwdriver with the notched
tip (see Figure 12) to loosen the slotted lock ring
securing the pivot-adjustment screw to the stationary
base (see Figure 14).
Figure 14 – Loosen the slotted lock ring
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 9 of 18
Once the slotted lock ring has been loosened, remove
the screwdriver handle from the bores in the revolving
turret and the stationary base (which is locking the
revolving turret to the stationary base) to get it out of
the way. Unscrew and remove the slotted lock ring
from the pivot-adjustment screw (see Figure 15).
Figure 15 – Remove the slotted lock ring
Remove the Pivot-Adjustment Screw
With the slotted lock ring removed, use a suitable
slotted screwdriver to unscrew and remove the pivotadjustment screw from the center bore of the
stationary base (see Figure 16). Note that there is a ¼”
bearing ball in the center bore of the stationary base,
beneath the pivot-adjustment screw. Do not allow this
bearing ball to fall out or it may become lost.
Figure 16 – Remove the pivot-adjustment screw
Remove the Center-Pivot Bearing Ball
Use a tweezers or other suitable tool to remove the ¼”
bearing ball from the center bore in the stationary base
(see Figure 17).
Figure 17 – Remove the center-pivot bearing ball
Remove the Mechanical Detent Stop
The next step is to remove the mechanical detent stop.
Use a suitable JIS screwdriver to remove the two M2x4
pan-head screws securing this stop to the stationary
base of the turret assembly (see Figure 18). These
screws are staked in place with adhesive and can be
surprisingly stubborn, so be sure to use the proper JIS
screwdriver to prevent damaging the screw heads. It
might also be helpful to heat the screws with a heat gun
before loosening them, but do not melt the black
knurled-rubber grip ring in the process.
Figure 18 – Remove the screws securing the detent stop
Remove the loose mechanical detent stop from the
stationary base (see Figure 19).
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 10 of 18
Figure 19 – Remove the mechanical detent stop
Remove the Black Knurled-Rubber Grip Ring
Carefully remove the black knurled-rubber grip ring
from the outer perimeter of the revolving turret (see
Figure 20), being careful not to stretch or damage it in
the process. This ring is held onto the turret with a few
spots of adhesive, so proceed carefully here.
Figure 20 – Remove the knurled-rubber grip ring
Remove the Threaded Retaining Ring
The stationary base is held inside the recess of the
revolving turret by the threaded retaining ring (see
Figure 21).
Figure 21 – Components of the turret assembly
Place the turret assembly into a suitable work vise and
use a heat gun to thoroughly heat the turret assembly,
to soften the internal grease. Then use a center punch
or nailset tool to loosen the threaded retaining ring by
placing the tip of the tool into one of the four tooling
holes in the threaded retaining ring (see Figure 21) and
driving the threaded retaining ring counter-clockwise by
carefully tapping the tool with a small hammer or mallet
(see Figure 22). Be careful and do not accidentally put
the center punch or nailset tool into one of the five
detent notches in the revolving turret (instead of into
one of the four tooling holes in the threaded retaining
ring), or the revolving turret will be irreparably
damaged when the punch is struck by the mallet.
Figure 22 – Loosen the threaded retaining ring
Continue loosening the threaded retaining ring and
remove it, being careful that the perimeter bearing balls
beneath the threaded retaining ring do not fall out and
become lost in the process (see Figure 23).
Figure 23 – Remove the threaded retaining ring
Remove the Perimeter Bearing Balls
Carefully remove the 3/32” bearing balls (there are 80
of them) from the channel formed by the outer
perimeter of the stationary base and the inner
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 11 of 18
perimeter of the revolving turret. A small magnet can
come in handy here (see Figure 24).
Figure 24 – Remove the perimeter bearing balls
Remove the Stationary Base from the Turret
Once the perimeter bearing balls have been removed
from the channel, lift the stationary base free of the
recess in the revolving turret and remove it (see Figure
25).
Figure 25 – Lift and remove the stationary base
Clean Grease from the Various Components
Use a suitable solvent (e.g., acetone) to thoroughly
clean all the old grease from the stationary base,
revolving turret, threaded retaining ring, perimeter
bearing balls, center-pivot ball, mechanical detent stop,
pivot-adjustment screw, and the slotted lock ring, in
preparation for reassembly.
Reinstall Stationary Base into Revolving Turret
Hold the stationary base such that the center pivot is
facing downwards, and then lower the stationary base
into the recess of the revolving turret (see Figure 26).
Figure 26 – Reinstall stationary base into revolving turret
Apply Ring of Grease for the Perimeter Balls
The next step is to apply a ring of grease into which the
perimeter bearing balls will be placed. Carefully apply a
ring of grease (item 8 of Appendix 1) into the channel
formed between the outer perimeter of the stationary
base and the inner perimeter of the revolving turret
(see Figure 27). Do not apply too much grease here, to
minimize the squeeze-out that will occur when the
threaded retaining ring is reinstalled to hold the
stationary base into the recess of the revolving turret.
Figure 27 – Apply ring of fresh grease for the bearing balls
Reinstall the Perimeter Bearing Balls
Use tweezers to carefully set the 3/32” bearing balls
(there are 80 of them) into the grease ring (see Figure
28), placing the bearing balls as close together as
possible as you proceed.
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 12 of 18
Figure 28 – Place the bearing balls into the ring of grease
Reinstall the Threaded Retaining Ring
Carefully engage the threads of the threaded retaining
ring with the threads in the revolving turret (see Figure
29).
Figure 29 – Engage the threaded retaining ring
Use a suitable lens-spanner tool (item 6 of Appendix 1)
in a pair of opposing tooling holes to tighten the
threaded retaining ring2 (see Figure 30).
Figure 30 – Tighten the threaded retaining ring
2
Or use a center punch or nailset tool to snug the threaded retaining ring by
placing the tip of the tool into one of the four tooling holes and lightly
tapping the tool with a small hammer or mallet to drive the threaded
retaining ring clockwise.
While holding the stationary base in one hand, spin the
revolving turret multiple times in both directions with
the other hand, to drive out any excess grease from
beneath the threaded retaining ring. Use dry cotton
swabs to remove any grease squeeze-out (see Figure
31). Do not use a solvent here, otherwise the solvent
may run into the revolving turret mechanism and foul
the grease within.
Figure 31 – Remove any grease squeeze-out
Apply Grease to the Center-Pivot Bore
Apply a small amount of grease (item 8 of Appendix 1)
into the center-pivot bore of the stationary base for the
¼” bearing ball (see Figure 32).
Figure 32 – Apply grease to the center-pivot bore
Reinstall the Center-Pivot Bearing Ball
Now that the center-pivot bore has been greased,
reinstall the ¼” bearing ball into the freshly greased
center-pivot bore. The grease will hold the center-pivot
bearing ball in the proper position during subsequent
reinstallation of the pivot-adjustment screw (see Figure
33).
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 13 of 18
Figure 33 – Place bearing ball into the center-pivot bore
Apply Grease to Top of the Center-Pivot Ball
Apply a small amount of grease (item 8 of Appendix 1)
onto the top of the ¼” bearing ball in the center-pivot
bore (see Figure 34).
Figure 34 – Apply grease to the top of the bearing ball
Reinstall the Pivot-Adjustment Screw
Use a suitable slotted screwdriver to reinstall the pivotadjustment screw into the threaded bore in the center
of the stationary base (see Figure 35). Carefully snug
the adjustment screw just to the point where a slight bit
of resistance is felt. Test the feel of the revolving turret.
If the motion feels rough, back the screw off a bit until it
feels smooth. Leave the screw in this position.
Figure 35 – Reinstall the pivot-adjustment screw
Reinstall the Slotted Lock Ring
Carefully engage the threads of the slotted lock ring
with the pivot-adjustment screw (see Figure 36).
Figure 36 – Reinstall the slotted lock ring
Spin the revolving turret until one of the five threaded
objective bores in the revolving turret aligns with the
bore in the stationary base. Insert a suitably sized
screwdriver handle into these bores to lock the
revolving turret to the stationary base. Use a suitable
tool (see Figure 12) to snug the slotted lock ring down
to lock the pivot-adjustment screw in place (see Figure
37). Do not allow the pivot-adjustment screw to rotate
while tightening the slotted lock ring.
Figure 37 – Tighten the slotted lock ring
Verify the Feel of the Revolving Nosepiece
Hold the turret assembly by gripping the stationary base
in one hand and spin the revolving turret with the other
hand. The motion of the turret should not feel gritty,
erratic, or excessively stiff. If it does, loosen the slotted
lock ring, readjust the pivot-adjustment screw, and
retighten the slotted lock ring (as described above) until
the turret motion feels acceptable.
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 14 of 18
Clean Off Any Visible Grease
Use a suitable solvent (e.g., mineral spirits) and a clean
rag or tissue to thoroughly clean any visible grease from
the exterior of the turret assembly. Be careful while
removing the excess grease, to prevent any of the
solvent from dripping into the revolving turret
mechanism and fouling the grease within.
Reinstall the Mechanical Detent Stop
Place the mechanical detent stop in position on the
stationary base, aligning the two holes in the
mechanical detent stop with the tapped holes in the
stationary base (see Figure 38).
Figure 38 – Place the mechanical detent stop in position
Use a suitable JIS screwdriver to reinstall two M2X4
pan-head screws to secure the mechanical detent stop
into place (see Figure 39).
Figure 39 – Secure the detent stop with two screws
Apply Grease to the Mechanical Detents
Apply fresh grease (item 8 of Appendix 1) to the five
mechanical detent notches in the revolving turret (see
Figure 40). Be careful that you do not get grease
anywhere else.
Figure 40 – Apply grease to the five detent notches
Reinstall the Protective Cover
Place the protective cover into position on the back side
of the turret assembly, lining up the three holes in the
protective cover with the tapped holes in the stationary
base (see Figure 41).
Figure 41 – Place cover in position on the turret assembly
Use a suitable JIS screwdriver to reinstall three M2X3
countersink screws to secure the protective cover onto
the stationary base (see Figure 42).
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 15 of 18
Figure 42 – Secure protective cover using three screws
Reinstall the Knurled-Rubber Grip Ring
The final assembly step for the turret assembly is to
reinstall the black knurled-rubber grip ring around the
outer perimeter of the revolving turret and secure it in
place with a suitable color-matching adhesive. Black
silicone RTV is a good choice of adhesive here, since it
will bond well with the metal of the revolving turret as
well as to the black knurled-rubber grip ring.
Additionally, any of the inevitable squeeze-out that is
not removed will not be visible. Apply two dabs of black
silicone RTV (item 7 of Appendix 1) onto the outer
perimeter of the revolving turret, spaced approximately
180° apart (see Figure 43).
Figure 43 – Apply black silicone RTV to revolving turret
Carefully reinstall the knurled-rubber grip ring onto the
outer perimeter of the revolving turret, making sure to
not stretch or damage the grip ring (see Figure 44).
Figure 44 – Reinstall the knurled-rubber grip ring
Use dry cotton swabs to thoroughly remove any visible
silicone RTV squeeze-out (see Figure 45).
Figure 45 – Remove any silicone RTV squeeze-out
Reinstall Wedge Mount and Corrective Optics
In order to guarantee proper optical alignment of the
turret assembly, and in order to minimize the
mechanical strain in the corrective-optics assembly for
polarizing work, reinstall the wedge mount and
corrective-optics assembly per the following procedure.
Place the wedge mount in position on the stationary
base of the turret assembly, aligning the four screw
holes in the wedge mount with the tapped holes in the
stationary base (see Figure 46).
Figure 46 – Place the wedge mount in position
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 16 of 18
While holding the wedge mount in this position, place
the threaded end of the corrective-optics assembly
through the center bore of the wedge mount and screw
the corrective-optics assembly into the tapped center
bore of the stationary base (see Figure 47). Tighten the
corrective-optics assembly until it is hand tight, then
back it off approximately ¼ turn. The barrel of the
corrective-optics assembly fits the hole in the wedge
mount with very tight tolerances, and this precision fit
holds the wedge mount in the proper physical location
so that the mounting screws can be reinstalled.
Figure 47 – Reinstall the corrective-optics assembly
Use a suitable JIS screwdriver to reinstall four M2.6X25
pan-head screws to secure the wedge mount onto the
stationary base of the turret assembly (see Figure 48).
Figure 48 – Reinstall screws to secure the wedge mount
Use non-marring pliers or a suitable strap wrench to
grip the barrel of the corrective-optics assembly and
tighten the corrective-optics assembly a bit beyond
hand tight (see Figure 49).
Figure 49 – Tighten the corrective optics assembly
Reinstall the Reverse Nosepiece Assembly
Hold the reverse nosepiece assembly in place on the
top of the arm (see Figure 50) and align the three screw
holes in the arm with the tapped holes in the wedge
mount on the reverse nosepiece assembly (see Figure
51).
Figure 50 – Hold reverse nosepiece assembly up to arm
Figure 51 – Align holes for the mounting screws
While holding the reverse nosepiece assembly in this
position, use a suitable JIS screwdriver to reinstall three
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 17 of 18
M2.6X14 pan-head screws to secure the reverse
nosepiece assembly onto the arm (see Figure 52).
Figure 52 – Reinstall three screws to secure it to the arm
Ready for Service
The microscope stand with the newly reconditioned
reverse nosepiece assembly is now ready to be put back
into service.
Requirements for Periodic Maintenance
Periodic cleaning and application of fresh grease to the
mechanical detent notches in the stationary base is
necessary to minimize wear of the mechanical detents,
thereby maximizing the useful service life of the reverse
nosepiece assembly. Follow the procedures detailed in
this document to remove the reverse nosepiece
assembly from the microscope stand, remove the
wedge mount and corrective-optics assembly, and then
remove the protective cover to expose the mechanical
detent notches. Next, clean and re-grease the exposed
mechanical detent notches and reassemble the reverse
nosepiece assembly, and then reinstall it onto the
microscope stand. If the equipment sees heavy usage,
this service should be performed on a six-month
interval3.
Problems with the Turret Assembly
A few problems with the turret assembly can
sometimes be found in the reassembled nosepiece. The
first will be seen if one or more of the mechanical
detents are excessively worn. This will cause radial float
of the revolving turret in one or more of the objective
positions, and these objectives will have trouble
returning to and maintaining their proper index
position. This can make it difficult to utilize some
illumination types, such as phase contrast, since the
3
Field experience has shown that even heavily used scopes (such as those
used in hospitals and clinical lab settings), when lubricated on a six-month
interval, can be expected to provide many years of trouble-free service.
phase annuli will not be able to hold an acceptable
alignment due to variations in objective indexing.
The other problem that may be seen is caused by
overall float of the revolving turret, relative to the
center point of the stationary base. If there is excess
play in the center-pivot ball, such that the turret is not
held in the exact center point, the whole turret may
move slightly, resulting in poor objective centering and
all that that entails. This problem may be encountered
if the threaded retaining ring has not been properly
snugged down, or if the center pivot-adjustment screw
has not been properly adjusted to remove the play in
the center-pivot mechanism.
A Few Words about JIS Screws
Screws with JIS heads are frequently 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 driver
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 53).
Figure 53 – A typical JIS Screw
Original Olympus Documentation
A scanned PDF of an early version of the Olympus
Research Microscope Series BH2 (BHS) Repair Manual is
available for download at various microscope-related
hobbyist sites on the internet. This document can be
found by searching for the title in an internet search
engine, such as Google or Bing.
Complete Teardown, Cleaning, and Reassembly of the Olympus BHTU Reverse Nosepiece Assembly Rev. 2 Page 18 of 18
Appendix 1
Sources for Replacement Parts, Tools, and Supplies Referenced in this Document
Table 1 lists specific information for the various parts, tools, and supplies discussed in this document. The pricing and
availability listed below is accurate as-of June 2018 but is subject to change without notice.
Item
Description
Manufacturer
Manufacturer Model #
Vendor
Vendor #
Price
1
Heat gun, electric, 1500W
Drill Master
---
Harbor Freight
96289
$12.99
2
Screwdriver set, JIS, 4 pieces
Hozan
JIS-4
Amazon
---
$19.10
3
Bearing balls, chrome steel, 3/32” G25, 100-count
various
---
Amazon
---
$4.92
4
Bearing balls, chrome steel, 1/4”, G25, 100-count
various
---
Amazon
---
$5.99
5
Pliers, soft-jaw
---
Non-Scratch Pliers
Micro-Mark
---
$34.95
Pliers, soft-jaw
Tamiya
74061
Amazon
---
$26.27 6 Lens-spanner tool, pointed tips
various
---
Amazon
---
$14.95 7 Silicone gasket RTV, black, 3oz
J-B WeldTM
32329
Amazon
---
$7.08
Silicone gasket RTV, black, 3oz
Harbor Freight
---
Harbor Freight
90024
$3.99
8
Plastilube® Brake Grease, 75cc
Plastilube®
ATE70015
Amazon
---
$8.82
Plastilube® Brake Grease, 75cc
Plastilube®
ATE70015
Autohausaz
1161688
$8.35
Mobilith SHCTM 220 synthetic grease, 13.4oz
Mobil
SHCTM 220
Amazon
---
$18.87
Table 1 – Parts, Tools, and Supplies
Table 2 lists the contact information for the vendors referenced in Table 1.
Vendor
URL
Local Phone
Toll Free
Fax
email
Amazon
www.amazon.com
---
---
---
---
Autohausaz
www.autohasuaz.com
---
---
---
sales@autohausaz.com
Harbor Freight Tools
www.harborfreight.com
---
1-800-423-2567
---
---
Table 2 – Vendor Listing
How to Contact the Author
Please feel free to direct any questions or comments regarding
this document (or BH-2 microscopes in general) to the author at
the following email address: carlh6902@gmail.com
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