Complete
Teardown,
Cleaning,
and
Reassembly
of
the
Olympus
BH
‐
2
Sliding
Focus
Block
Revision
2
Page
7
of
23
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
of
the
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
used
to
clean
most
painted
surfaces)
or
will
dissolve
or
damage
plastic
parts.
Do
not
allow
untested
solvents
to
contact
any
plastic
parts
or
any
painted
surfaces.
Before
using
a
solvent
to
clean
plastic
parts
or
painted
surfaces,
test
a
small
amount
of
the
solvent
in
an
inconspicuous
area
(such
as
inside
a
plastic
knob)
to
ensure
compatibility
with
the
plastic
part
or
painted
surface.
Never
use
xylene
to
clean
nylon
parts,
as
xylene
dissolves
nylon.
Isopropyl
alcohol
and
trichloroethylene
will
cause
swelling
of
nylon
due
to
solvent
absorption.
The
list
of
solvents
generally
considered
safe
for
nylon
includes
acetone,
diethyl
ether,
heptane,
mineral
spirits,
naphthalene,
and
turpentine.
Recommended
Lubricants
The
Olympus
BH2
(BHS)
repair
manual
(see
the
Original
Olympus
Documentation
section
of
this
document)
recommends
using
grease
in
the
sliding
focus
block
mechanism.
However,
based
on
decades
of
experience
servicing
BH
‐
2
equipment
in
the
field,
some
microscope
repair
technicians
recommend
omitting
the
grease
entirely
from
the
sliding
focus
block,
in
order
to
reduce
the
fouling
of
the
mechanism
which
can
occur
if
dust
and
debris
accumulates
in
the
greased
slides,
as
well
as
reducing
any
stiffness
or
sluggishness
that
will
result
from
thickening
of
the
grease.
Given
this
conflicting
guidance,
consider
that
grease
may
be
applied
to
the
slide
per
the
Olympus
guidance,
at
the
risk
of
requiring
more
frequent
maintenance
to
keep
the
mechanism
clean
and
freely
moving,
and
grease
may
be
omitted,
at
the
risk
of
more
long
‐
term
wear
of
the
mechanical
components.
Mobil
Polyrex
TM
EM
or
Molykote®
44
(items
7
and
5
of
Appendix
2
)
are
recommended
if
lubrication
is
desired
in
the
slide.
Regardless
of
whether
or
not
lubrication
is
used
in
the
slide,
a
heavy
grease
such
as
Dow
Molykote®
111
(item
6
of
Appendix
2
)
should
be
used
to
hold
the
guide
rails
in
place
during
reassembly,
and
any
excess
grease
remaining
after
the
guide
rails
have
been
installed
should
be
thoroughly
removed
before
proceeding
with
the
reassembly
of
the
sliding
focus
block
mechanism.
Label
Parts
for
Identification
and
Reassembly
There
are
many
small
parts
that
make
up
the
sliding
focus
block
mechanism.
It
is
critical
that
these
be
bagged
and
tagged
as
they
are
removed
to
prevent
them
from
getting
lost
and
to
facilitate
their
proper
identification
during
reassembly.
Part
of
a
Comprehensive
Focus
Overhaul
Maintenance
of
the
sliding
focus
block
is
best
performed
as
part
of
a
comprehensive
overhaul
of
the
entire
focus
mechanism.
It
is
best
performed
after
a
teardown
of
the
coaxial
focus
mechanism
has
been
performed,
since
this
service
is
easier
to
perform
while
the
focus
knobs
and
other
focus
parts
are
not
present
on
the
arm.
Accordingly,
this
document
describes
(and
the
accompanying
photographs
show)
the
service
being
performed
on
a
stand
that
has
had
the
coaxial
focus
block
completely
disassembled,
per
the
Complete
Teardown,
Cleaning,
and
Reassembly
of
the
BH
‐
2
Coaxial
Focus
Mechanism
document.
In
almost
every
case
where
the
sliding
focus
block
is
sluggish
and
needs
to
be
serviced,
the
coaxial
focus
mechanism
is
also
in
need
of
a
similar
service,
so
it
makes
sense
to
perform
both
repairs
at
the
same
time.
Protect
the
Exposed
Mounting
Dovetails
Before
proceeding
with
the
teardown
described
in
this
document,
cover
the
top
of
the
microscope
arm
(i.e.,
the
exposed
mounting
dovetails
for
the
viewing
head
and
nosepiece,
if
applicable)
with
a
clean
plastic
bag
and
secure
this
with
a
rubber
band
or
adhesive
tape
to
keep
dust
out
(see
Figure
2
).
This
is
especially
important
on
BHSU
and
BHTU
stands
which
have
an
optical
correction
lens
located
just
below
the
viewing
head
to
correct
for
the
difference
in
tube
length
introduced
with
the
reversed
nosepiece.
Figure
2
–
Protect
the
top
of
the
arm
from
dust
