[3dem] Manual plunge freezers

[Mariena Silvestry Ramos]

Hi Winnie,


I don't have any drawings but can perhaps point a couple of common features I've seen and found useful:


A guillotine-type mechanism for plunging

A foot (or hand, whichever is most convenient) pedal to release the plunger part

A place to hold the tweezers and secure them tighly

Depending on the types of blotting you want to do, the ability to orient the tweezers (to rotate, and perhaps have steps, so you can change/vary the height of the tweezers)

A control mechanism to stop the plunger from going all the way down and prevent you from taco-ing your grids (I know, highly technical for bending your grids, but they do honestly resemble tacos) and your grids

A cup to add LN2

A smaller cup to add the cryogen (ethane, ethane/propane mix, propane)

A thermocouple to heat the smaller cup, should you only use ethane, which will solidify at some point

Perhaps a movable shield, in case you want extra protection from splashes

A place to store grid boxes, if desired


Back when I was at the NYSBC, Prof David Stokes had what my wonderful boss Ruben called the Vitrobox, which was a plastic enclosure, with openings for your hands/arms, and we'd spray warm water on the walls of the plastic enclosure (made of our plexiglass) to increase the humidity (on could also have a small apparatus to boil water constantly) on the chamber. We even had a mat sci user who built an attachment where she could place magnets of different strengths for her field changing experiments.


Doing a quick search I came across this design: https://twitter.com/ChristosGSavva/status/1013776357296308226 which has an enclosure for the area where the sample is applied. The Baker lab has a great page (pdf) with all the parts their manual plunger has: https://cryoem.ucsd.edu/procedures/plunge.shtm. There's also this portable one which includes more info on the plunging bar/mechanism: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4677670/.


And previously mentioned on the list: https://mail.ncmir.ucsd.edu/pipermail/3dem/2015-January/003678.html


Unfortunately the Cornell shop isn't taking outside projects, but depending on where you're located, you may be able to contact a local university with a decent physics or engineering program and inquire. Or online. I've had a pleasant experience ordering specialty machined parts from Kurt Lesker.


Hope this helps,


Mariena

________________________________
From: 3dem <3dem-bounces at ncmir.ucsd.edu> on behalf of Winnie Liang <winnie9388 at gmail.com>
Sent: Thursday, March 7, 2019 3:13:11 PM
To: 3dem at ncmir.ucsd.edu
Subject: [3dem] Manual plunge freezers


Dear all,

My lab is looking to build a manual plunge freezer for our cryo-EM work, and would appreciate any sugestions on good, cheap machine shops that do this sort of work.  Furthermore, we do not have any idea on what components should go into the cryo plunger design.  If you have any previous designs that you don't mind sharing or know of any resources that can point us to, we would really appreciate it as well.


Thank you for your help!


Winnie
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