More Freezing Microtome ?s

[myxomop]

Hello Micro-Macro Friends,

I have a question regarding the building/assembling of a freezing microtome for use in mycological sample preparation. This is a follow up to my previous two posts on the subject:

viewtopic.php?f=25&t=43617&p=274439#p274439
viewtopic.php?f=25&t=42994&p=270521#p270521

There is a Physitemp BFS-30TC unit for sale on ebay, complete with stage, cables, hoses, etc., for a pretty affordable price:

https://www.ebay.com/itm/265441165928

Alas, according to the Physitemp rep I spoke to months ago, this model will not work with the American Optics 880 microtome I own (I actually have a second one as well in case I need to harvest the first one for parts). I also notice that there is no stage post with this unit, but rather a simple metal plate beneath the freezing stage. If I'm not mistaken, this is designed for use with a sledge microtome. I wonder if this community can recommend any freezing microtome which will be compatible with this BFS-30TC unit, since freezing stage controllers and stages seem to come up on the used market *far* more rarely than microtomes do, and I am therefore willing to part with my two AO880s if need be.

Many Thanks,

-Danny

[Macro_Cosmos]

Seems like you and I are on a similar mission here.

In this industry, "it does not work with your model" simply translates to "I look forward to your purchase order for an officially compatible system" -- to put it very bluntly. I would often love to recommend solutions that do work, but it is rarely in the interest of the business. Anyway, I do not see why the freezing stage cannot be adapted to work with your AO 880 microtome. The AO 880 microtome has a vise clamp, you may simply replace it with a larger one to clamp that freezing stage. If your clamp is missing, you can simply get one and attach it to an appropriately sized rod, or just weld the rod to the freezing stage's plate.

I have a Leitz microtome with a "BFS" coded freezing stage, it is mounted to a rod, 2 tubes for water and two wires. I thought finding the controller would be impossible. Thanks to your post, turns out "BFS" is a part number for Physitemp, I have been looking up the wrong brand! The entire stage looks very simple. I think it would be totally possible to make a controller, precise temperature control would not be possible but it is not needed in my case.

In your older post, you mentioned "Erma microtome". What is the model? There is one listed on eBay Australia: eBay item number: 144228700280
I want the ringing table and the clamp if it is compatible with my Leitz, and I would not mind another knife. The seller agreed on $850 I think, which was not as good as his original intentions to just sell me the ringing table. If this just happens to be the compatible model and you intend to purchase it, I am happy to forward it to you. I will try and negotiate a better price, the seller has been trying to sell it for over a year.

With all that said, I think we both have a better chance at a homebrew system with a Peltier cooling element. Below are some resources I have found on this very subject. It is all in the German language.
1. Microtome specimen holder: https://www.mikroskopie-forum.de/index. ... #msg247584
2. Peltier cooling element for freezing stage: https://www.mikroskopie-forum.de/index. ... ic=38722.0
Note: sufficient heat dissipation is required, or else the Peltier element will explode. The solution here is bulky, I would simply go with heat pipes and water cooling, which leads us to below.
3. Water-cooled Peltier element with complete homebrew controller: https://www.mikroskopie-forum.de/index. ... ic=14819.0
Temperature control might not be absolutely precise, but -18C is very good! I plan to chop up weird innocent plants I find in the neighbourhood.
4. Holder for hand microtomes: https://www.mikroskopie-forum.de/index. ... ic=33231.0
5. More Peltier information: https://www.mikroskopie-forum.de/index.php?topic=1254.0

I believe it is possible to make a controller for my cooling stage, just two wires and two tubes. It cannot be that hard?!
A friend told me to just get a cheap portable freezer, he uses one. Simply freeze the specimen, take it out and chop away quickly. I like the simplicity of this solution.

[myxomop]

Hello Macro_Cosmos,

Thank you for your prompt and comprehensive reply. The Erma model to which I referred in a previous post is this one:



I wish I had a larger/higher resolution image, but that's the best I can do. This is a radial microtome that Physitemp sold with their BFS 3MP/5MP units some years ago (early 1990s), both of which are now very discontinued. My learning of this came as a result of finding an auction for a BFS-5MP unit which included the following stage and post:




When I asked Physitemp if this 5MP and its accompanying stage would work with my AO880, they informed me it would not, due to difference between the post diameter in the auction and the post slot (?) diameter of the AO880. A friend suggested going for it anyway, suggesting that such a minor incompatibility as this could be overcome with a minimal amount of machining. Alas, the $500 offer that I made on the auction -- following the Physitemp rep's appraisal of what he thought the unit was worth -- so offended the seller that he ceased all communication, and inexplicably ended the listing shortly thereafter.

The radial Erma in the ebay listing you reference is beautiful, and tempting, especially if the stage and hose attachment would pair relatively seamlessly with a Physitemp unit. I was wondering whether or not the included stage would, with all its concentric indentations, hold a single droplet of gum arabic, as is needed for the technique I was taught and will be performing on whatever equipment I purchase. The diagram shown here:



taken from this Erma manual shows the technique I have in mind (and connected to what I think is a much older Physitemp unit, no less). Then I noticed the five, upside-down, metal disks with the posts sticking up, which I suspect are swappable stages:



Is that correct?

I would surely be interested in a more homespun (and therefore potentially much less expensive) setup, like what you describe at the end of your post, but this exceeds my abilities, is beyond my meager comprehension for such things, and would take more time than I could personally commit. If you happen to construct such a device for your own purposes, and could construct another for less than the ~$1000 it looks like I will need to spend to assemble my home freezing microtome setup, please keep me posted. You may have a future customer in me.

In the meantime, as for "MacGyvering" the larger stage of the BFS-30TC with my AO880, the Physitemp rep I spoke to all those months ago described precisely how/why this would not work, but I can't remember specifics. I tried to contact them again recently, but their phone system was having problems, and they have not responded to my email from a week or so ago. I will try them again and post back here with my findings. I think the vise clamp you refer to is this one:



I'll have to check to see if either of the AO880s I purchased actually came with one of these. They may not have! It would also be helpful to know the maximum stage width that stock clamp can accommodate, and then see if that is too small for the larger BFS-30TC stage, and if so, contemplate my options (such as replacing the clamp, as you propose). I am apprehensive about welding anything to anything else, if for no other reason than wishing to be able to fully disassemble this setup for transport, when needed. It also strikes me as sort of... sketchy to be welding around all those wires that line the underside of the stage. Sketchy, but not impossible!

Thanks again for your engagement, and looking forward to reading your reply.

Best,

-Danny

[myxomop]

Quick reply to mention that the auction has ended. I hope the buyer gives such a beautiful piece a nice home and many more years of use.

[myxomop]

bumping this thread, as my multi-year search continues unabated.