In article
,
RS at work wrote:

I am going to need a chamber that is somewhere in the order of 14X14X6
inches. If I went with a chunk of pipe, that would have to be
something like 16" diameter. The down side to this would be cost and
bulk. The more empty space inside the chanber the longer evacuation
time.

Also if I used a 16" inch pipe it would also be difficult to make a
door. The door would have to be hinged and by the time I dod all of
that work, it would get pretty pricy.

Trivial to make a door. No hinge required. Take a 6 inch length of 16
inch pipe, weld a plate on the bottom (years of vacuum experience says
1/4" steel plate would probably do nicely, thinner would work if you
domed it a tad) and put a flange (better yet, get 6" with a flange cut
off a pipe at the junkyard) with an o-ring groove (hey - metalworking!)
on top. A crapped out 16" valve body and a blank flange for the bottom
might doing it from stock parts with no cutting. For 16" a 1" Lexan top
(if you want to see what happens) should work - we used 1-1/2 or 2" for
a 24-30" dia unit much like this (a bit bigger) that was primarily used
for vacuum-casting epoxy. The vacuum holds the lid on quite well indeed.
Making it cheaply is a matter of picking the right junkyard (try one
that gets stainless steel scrap from a university), and seeing the right
things in the junk.

If you want the opposite of doing it right, try a 12" port and a sheet
of window glass. Does a heck of a job on a tubomolecular pump running
full speed (it didn't break right away, so the researcher/culprit
actually got the high vac pump running before he filled it with glass
shards.)

If evacuation time is an issue for you at food-sealing pressures, you
need a better pump...

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