Instruction manual

Thermo Scientific Rotary Microtome Microm HM 340 E

Microm International GmbH

part of Thermo Fisher Scientific

Otto-Hahn-Str. 1A

69190 Walldorf / Germany

387831 - English

During practical work the angle of inclination is our

so-called clearance angle, i.e. the angle between

lower facet surface and block surface. The optimal

inclination slightly differs for each knife, as the

wedge angles as well as especially the facet

angles on the individual knives are not absolutely

identical.

The knife must never be placed too flat. This way,

the blade does not cut into the block at all. Only

the rear side slides over the sectioning surface

(see opposite figure).

An inclination, which is too steep, is also

unfavorable as the knife might vibrate too much

while sectioning. The so-called "chatters" appear

on the block surface as well as on the sections.

These chatters are parallel stripes in relation to the

knife edge having negative effects on the

microscopical evaluation of sections.

Between these two limit cases, the correct knife

inclination must be determined. A clearance angle

between facet angle and block surface of approx.

5° is normal.

Caution:

Different microtome producer use

different scalings for their clearance

angle adjustment, resulting from

different calculation bases. The clearance angle

might refer to the facet surface or to the angle

between knife main surface and block surface. As

the facet has a divergence from the knife main

surface of approx. 5°, the difference is approx. 5°.

Set the correct angle on Microm instruments at

10°c.

Fig. 52

Fig. 53

Fig. 54