Rae Staskiewcz - Re microm Microtome

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From:bbracing <bbracing@silk.net> (by way of histonet)
To:histonet <histonet@magicnet.net>
Content-Type:text/plain; charset="us-ascii"

Rae -  I have two microm automatics, and just love them.  The problem that
you are having may be the knife holder.  I have found that these holders
are very easily damaged, and even the smallest imperfection in the clamping
surface will cause a vibration problem.  This is because, an imperfection
will cause the blade to be clamped tightly in one spot, but not the rest of
the blade, so it permits the blade to vibrate.  I have a small machinest
dressing file, about 5 inches long that I use to dress the imperfections
out of both the lower clamping surface and the upper clamping surface.
Quite often, when you run the file across these surfaces you will
immediately see that it is removing very small amounts of metal in only one
spot. Dress the holder down untll the entire surface shows new dressing
There is a second problem that I had with one of my units that is a little
more difficult to detect.  With this unit the upper clamping plate  griped
the blade about 1/2 way down, instead of at the upper most portion.  Again
this let the blade vibrate when cutting any thing but the softest of
tissues.   To determin if this is the problem, you can try to observe the
clamping plate and knife end on, to see if the clamping plate is in fact
clamping the blade at its upper most edge.  Or, you can use some very thin
feeler gauges ( 0.01 - 0.02 ) to see if you have a clearance problem, or in
my case I had to revert to some machinests blueing which I painted on the
underside of the upper clamping plate, then clamped a blade in the holder.
The blueing transfers onto the blade, and shows you exactly where the
pressure points of the clamp are.  If this is the problem, then you have to
have the clamping plate reconfigured, ( I simply filed mine ) untill it
clamps the blade properly, which is along the upper most portion of the the
clamping plate as close to the cutting edge of the blade as possible.  On
more thing, with these units (and using feather blades) I have found that
they seam to cut best when the holder is showing 13 degrees of  knife angle.
Hope this is of some help.
Kerry Beebe
Kelowna Gen Hospital
Kelowna B.C. Canada

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