Dear Marc,

This was answered a few weeks ago, here is the copy below. You probably
received many ways to what you should and should not do, but all I can say
now is this way has worked for us and our customers for 40 years or more.

14 March 2001

Dear Marc,

I will try to make this easy to understand, our most popular knives for
cryostats are 22 degrees. For sectioning on a cryostat we sharpen with a 5
degree facet each side of the knife which gives us on a 22 degree angle
knife a total of 32 degrees. If the knife is used for wax sectioning then we
use a 7 1/2 degree facet each side of the knife. These facet angles can be
used and added to whatever knives you use except 'D' profile. I would keep
to a constant angle settings as above as if you keep increasing the angle
you will have to spend some time and loose valuable tissue finding the
correct angle each time you resharpen a knife, and eventually the angle will
be too great to get sections off.

Please note that in time the facets get very large this can cause a problem
for removal of cryosections, and the edge is not as durable causing more
frequent sharpening. This can be over come by having the faces of the knife
reground ( refaced) this then will virtually bring the knife back to its
original condition when new, at a fraction of the cost of a new knife.

We can or alternatively Hacker Instrument or other knife sharpening services
may be able to carry out this regrind for you, it cannot be achieved on an
automatic knife sharpener.

Please come back to me if all is not clear.

Best Regards


Alan Bright


Bright Instrument Co.Ltd.
St Margaret's Way
Huntingdon
Cambridgeshire
PE29 6EU
England

Tel No:+44 (0)1480 454528
Fax No:+44 (0)1480 456031
Email: AlanBright@brightinstruments.com
Web Site: www.brightinstruments.com




-----Original Message-----
From: Mrc advertisin [mailto:marckropholler@yahoo.com]
Sent: 27 February 2001 13:31
To: histonet@pathology.swmed.edu
Subject: microtome knifes


Dear people at histonet,

I have several basic questions on the use of microtome
knifes. We are using non-disposable knifes. First,
when sharpening the knife, should the knife angle
remain constant or steadily decrease with a quarter of
a degree or so? We get contradictory advise from the
more experienced people we ask. Second, what should
the clearance angle be for a C or D knife? If I
understand correctly it should be 2 to 4 degrees for a
C knife and 1 to 2 degrees for a D knife. I hope some
you can help us with these questions.

best regards
Marc Kropholler


AMC
dept. Medical Physics
Meibergdreef 9
Amsterdam
The Netherlands

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