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Re: Insulating Vacuum Spacer Fittings

Posted: Thu Apr 22, 2010 12:29 pm
by Doug Coulter
Lutz (and all).

I really, really recommend getting the Lesker catalog and reading each page multiple times. I'm not saying buy from them -- they are a convenience store with prices to match. But the tech info on what's available, how well each thing works and so forth will save more money than buying some odd thing from them will ever waste -- and sometimes that's way worth it to save the time over homebrew (even for me, with a shop that can make most things). I do like the above suggestions of plastic "gasket" and shoulder washers so you can still use steel bolts, though -- sweet idea.

The online Lesker and the printed catalog are two different animals -- request and get the true laptop version! It is the very cheapest and also the best education in high vacuum technique you can get.
They want this stuff to work for you, so they get to keep the money, and they try pretty darn hard.
Nothing they say in there...has been wrong for me so far, and I've tested all their assertations insofar as possible here. Very dense info in their "tech tips", no BS, just the straight factual operational experience talking there. You could spend a few hundred bucks on books and not get as much good and true info.

Re: Insulating Vacuum Spacer Fittings

Posted: Thu Apr 22, 2010 5:34 pm
by Linda Haile
I can see what you mean now. Is the socket like these?

Re: Insulating Vacuum Spacer Fittings

Posted: Thu Apr 22, 2010 6:34 pm
by Linda Haile
We Europeans also have access to stuff like this Carl.

It doesn't outgas and is good for 22kV/mm and 500 degrees C. ... OLEPBI.pdf

Nylaplas do a lot of other stuff as well.

Re: Insulating Vacuum Spacer Fittings

Posted: Mon Apr 26, 2010 10:25 pm
by lutzhoffman
Thanks for all the great tips on polymers, the spec sheets, and for the Lesker catalog tip. I have used the Lesker web site many times to ID flanges etc. but I did not know about the other handy features to be found here via the catalog. I will do this for sure. Lyn: you are 100% correct about the quartz part which I want to use. I figured for a hair over 20 bucks its not a bad deal at all, I should have just posted a pic on this also to be clear : )

Doug: When you talk about using metal bolts; I am assuming that are you talking about having the female threaded portion in the polymer spacer only going part way through the part, like with a tapped blind hole? Otherwise the metal bolts would short the top and bottom flanges, which I am trying to insulate, and only physically connect via the insulating spacer? Thanks......

Re: Insulating Vacuum Spacer Fittings

Posted: Tue Apr 27, 2010 1:27 pm
by Doug Coulter
I was talking about shoulder washers which are used all over for doing things like mounting semiconductors to grounded heatsinks when the semiconductor case isn't grounded. This is a washer with a tube that goes down inside the hole (all one piece). Usually made of strong nylon so it can take some compression from the bolt head while the bolt is only connected to the flange it's threaded into.
These are cheap and made in all sizes from tiny to big.

__| |__ < shaped like that. The bolt head would be on the bottom in this ascii art with the shank going up vertically. The advantage is that the metal bolt can still be used to get enough force to compress the insulating gasket without stripping threads.