[Histonet] Microm HM 355S Issues

Jay Lundgren jaylundgren at gmail.com
Fri Sep 23 12:16:14 CDT 2016

With most microtomes, 1 complete turn of the wheel equals one advance of
four microns, or whatever you have the micrometer set on.  What people
don't realize with the HM355 is that is doesn't take a complete turn of the
fine advance wheel to advance the specimen.

If I recall correctly, the advance will happen when the wheel rotates
somewhere between 90 and 180 degrees, or when the handle is from the 9 to 6
'o'clock position (the locking position being 12 o'clock.)  People don't
realize it has advanced, because they haven't made a full turn of the wheel
as they are rough cutting, then when they start their fine cutting,

With the HM355 microtomes, it is unwise to rough cut by "rocking".  If you
bring the wheel past a certain point, the sensor reads it as a complete
turn of the wheel and advances the block.  If you do it once, you might
only get a thick section, but if it happens 2 or 3 times in the course of
rough cutting, you will chunk out your block. It is safer, although much
slower, to rough cut by setting the micrometer on 10-15 microns and
rotating the fine advance wheel normally.

 Or, if you are very patient and careful, you can learn the specific spot
your microtome advances at, and rough cut by rocking, but just being
careful never to rock the wheel past the position where it will advance the


                                                    Jay A. Lundgren, MS

On Fri, Sep 23, 2016 at 10:29 AM, Duddey, Aimee via Histonet <
histonet at lists.utsouthwestern.edu> wrote:

> We are currently having the same problem with 2 of ours.  Stepper motor
> replacement did not work either.  I would be interested to hear any
> responses as well.
> Aimee
> -----Original Message-----
> From: Sandra Cheasty via Histonet [mailto:histonet at lists.
> utsouthwestern.edu]
> Sent: Friday, September 23, 2016 10:41 AM
> To: Histonet (histonet at lists.utsouthwestern.edu)
> Subject: [Histonet] Microm HM 355S Issues
> Hello,
>                 We have 2 Microm HM355S motorized microtomes. We use the
> motor to move the block close to the blade, but turn the wheel manually
> when sectioning. Both are "jumping" forward on their own occasionally while
> sectioning, which is unsettling and chunks into the block. One of them also
> backs up on its own as you're manually turning the handle, just as you're
> about to get a ribbon.
>                 The stepper motor has been replaced on one with no
> improvement. Any suggestions, remedies, or tales of similar issues and how
> they were resolved would be most appreciated.
> Thanks,
> Sandy
> Sandra J. Cheasty, HT (ASCP)
> Histology & Necropsy Supervisor
> UW-Madison, School of Veterinary Medicine
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