Issue 3 April 2011
9
3. OPERATION
The microtome should be installed on a sturdy bench at a height convenient for the operator.
It may be used with its long axis parallel to the bench, at right angles or obliquely.
There are many variations of the preparation procedure according to the type of specimen to
be sectioned, the size of the specimen and how the specimen is prepared.
The following general procedures can be applied to all uses:
3.1
Fitting the Object Holder
Pull the sledge away from the knife holders. Secure the required object holder by placing it in
the holder in the sledge slide (17). Set to correct height and lock by tightening clamp lever
(14).
Note that the clamp lever has a ratchet with its movement limited to prevent the lever being
left in positions where it could impact on other parts during sectioning.
3.2
Fitting and Adjusting the Knife
NB:
The term ‘knife’ used here also includes disposable blade holder.
a.
Slacken the knife clamp levers (10) just enough to let the knife slide into the knife
clamps from the side.
b.
Insert the knife, taking care to avoid touching the edge against the metalwork.
c.
Check that the knife lies flat on the pad pieces in the knife clamps and that the heel of
the knife is not caught up on the slot in the knife clamps.
d.
Screw the knife clamp levers down just sufficiently to steady the knife in position.
e.
Slacken the knife block clamp levers (12). Set the knife holders to the desired slew
angle, ensure the knife clamps still cover the ends of the knife. Set the knife to the
desired cutting angle and tighten the knife clamping levers.
f.
Check that the knife is still at the desired slew angles and tighten the knife block
clamp levers.
NB:
To ensure that the knife clamps are correctly aligned in the holders, the knife block
clamp levers must always be slackened before the knife clamping levers are
tightened.
3.3
Trimming the Specimen
Fit the specimen securely into the appropriate specimen holder on the microtome.
To trim excess material from the surface of the specimen block:
a.
First move the sledge towards the knife and adjust the specimen height using the
coarse advance so that the specimen is just below the knife.
b.
Either set the thickness control to cut thick sections, eg: 20µm, and move the sledge
back and forth repeatedly to trim the specimen.
c.
Or set the thickness control to zero and alternately raise the specimen slightly using
the coarse advance and move the sledge forward then backwards. This method is
quicker but should only be used if the operator is experienced in the use of base
sledge microtomes.
