MicrobeHunter.com Microscopy Forum

Hi together,
I recently acquired a tiny KOSMOS rotary microtome made by E. Zimmermann. KOSMOS is a german company that traded scientific stuff for decades. These little rotary microtomes were made in several different versions for at leas 65 years. Weight is about 5kg and it lives in a nicely made wooden box. It probably is the only rotary microtome that comes with a desk clamp! Originally it had a housing that went missing and a round mounting plate to melt paraffin blocks onto. The grey block holder on the photo is most likely a later addition. I removed it and replaced it with a clamp for modern tissue cassette blocks. It is a nice little microtome that can be carried to group meetings without dislocating one's back. The arm in front is part of an section The microtome was last used 35 years ago by a medical student and urgently needed a service. I dismantled it, cleaned an lubricated it,adjusted the guides and assembled it. I also glued the µ scale onto the base as it was ratling around without a mount. The knives had what looked like a little surface rust, but these very high carbon steels tend to develop rust that enters the material like a worm hole. I had to grind away quite a bit of steel to get an edge without nicks. Now it cuts nicely. As a sample I cut some sections of a paraffin embedded blackberry twig, sectioned to 10µ, stained with Wacker W3A Sim, perhaps too old, mounte in Euparal. The image will improve further when the Euparal dries on the 45°C hot plate.

Bob

What a little beauty !!

... I am Green with Envy

MichaelG.

I will try to find a matching stain for you, Michael!

Hi Bob,

very nice tool! Thanks for showing, unfortunately such things are no longer made nowadays. Seems that hobby microscopists are no longer a relevant target group.

These microtomes have been made for decades but rarely surface on ebay. It may have been in the catalog to impress customers without actually making money with it. There are stamped numbers "10" and "248", so probably very small series. For general home use I would suggest a bigger model from somewhen in the last 100 years. But I was especially interested in it for its portability to be ued for group meetings. My usual microtome is a Leitz base sledge microtome 1300 with over 40kg of weight and it is not much fun to move around.

Impressive instrument and a beautifully done plant section !

You can't taunt me with pictures and not show the mechanism!!!!

I have two prices for it. In 1913 it was about 2/3 of a microscope with two objectives and mono tube. In 1978 it was said to be priced like an SLR camera with 2 objectives. It kept it's value in a similar way as these references.

I can take a few more photos of cause.

MicroBob wrote: ↑

Wed Jan 12, 2022 6:49 am

I can take a few more photos of cause.

Please do, Bob … it looks very interesting.

MichaelG.

Hi together,
here some more photos. The next cut is set when the block holder moves upwards, short before the end pf the upwards stroke.
The long element in front is part of a section transport mechanism. The microtome used to have a housing, I'm not going to build one for it as the mechanism is easier to lubricate when open. Right now it swims in oil, im more inlined to oil a lot by habit of my profession. For most parts I have used HLP 68 hydrailic oil, for the vertical movement GLP 220, a sticky machine way oil. There are three doveteiled ways, one for the setting of the section thickness, one for the repeated up/down movement, one for the progress of the block towards the blade. The latter two are adjustable. Not original is the way the scale is mounted and the cassette holder, 3D-printed with a base soldered from two steel parts.

How well does it work? It is able to reproduce the same problems as I have with my heavy Leitz 1300 base sledge microtome , but it can also produce similar sections from a block like this. At a weight ratio of 5kg: 45kg I would say this is quite astonishing! The drawbacks are that there is no way to align the block and it has it's preferred speed of cut, making very slow cutting difficult. The small and light knives are easy to sharpen when attatching a small drill chuck with a slender handle to the tang. The lenght (or shortness) of the knives doesn't let much room for preparing the block with one part of the knife's edge and moving over for the real sectioning.

Bob

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Thanks for the photos, Bob … quite ‘inspirational’ : I will start drawing something along those lines
… for the far-distant time when I might consider making a small microtome.

Could you maybe add a few key dimensions to get things started ?

There’s no rush … see my signature line

MichaelG.

Hi Michael,
the front of the base is 96mm long. You should be able to find the other dimensions as close as necessary from there.
The dovetail ways are ground, it would be even better to scrape them. When building them it would be heltpul to choose good bearing partners, e.g. all cast iron. These sliding microtomes use roller guides: https://www.wsl.ch/en/services-and-prod ... tomes.html
Linear guides would have to be the versions with the highest preload level (no play) and "ball chain" "Kugelkette" type which runs considerably smoother than others.
You can contact me when you are about to start, it might be an interesting discussion, though I won't build on myself. I though about developing an amateur microtome as a product to sell but I don't see the market for it.

Bob

MicroBob wrote: ↑

Wed Jan 12, 2022 5:47 pm

Hi Michael,
the front of the base is 96mm long. You should be able to find the other dimensions as close as necessary from there.

Thanks, Bob … That should do nicely for now.

MichaelG.
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Edit: __ This might be of interest http://waywiser.fas.harvard.edu/objects ... -microtome