I just found this group as I was looking for info on vacuum stuff.
I am a machinist that now owns his own shop. I like to make things,
and my mirror needs recoating so...Hmm guess I'll make a chamber!
I'm going to weld up an eight sided chamber out of 1/2 inch alum.
plate. It will be around 20 inches across and 12 to 20 high.
Check out yarde metals drop zone for good prices on metal.
www.yarde.com
As for the cold trap, I have an old window unit that stoped cooling.
I brazed on a valve to fill it, R22 was the refridgerant, propane is
a drop in replacement so thats what I used. It is still low on
propane, but I saw -31F on the cold side with the blower off. Max
would be -41F, after that propane makes a vacuum. If you want to
replace R21 use 80 percent propane and 20 percent isobutane.
I have a rough pump and a gauge, but lack a oil diffusion pump
still, if you guys have any leads I'll check them out.
As for feed thru's will spark plugs work? How many amps can they
pass?
I also plan on trying to cast mirror blanks with a honeycomb back.
Thats a big project so well see how it goes. To support that project
I want to make grinding and polishing machines...like I said I like
to make things :)
Take care
Les
