On 13 May 2005 16:00:04 GMT, the renowned
(Chuck Sherwood) wrote:

My 11 year daughter is showing a strong interest in science.
We received a Edmunds catalog with lots of cool stuff in it.

I have always wanted to play with vacuum stuff when I was a kid
and I didn't get much of a chance so I figure now is my chance.

I figure it would be cool try to make a crude light bulb inside
a bell jar and things like that.

I looked at ebay and there are many vacuum pumps FA.

Do I need a two stage pump and how big of a pump do I need?
The killer is these things are heavy and shipping is expensive.

chuck

Two stage is necessary to do a lot of interesting stuff. Some of the
really interesting stuff requires a much harder vacuum than you can
get with a mechanical roughing pump, and you have to go to a diffusion
(oil, they used to use mercury) or turbomolecular pump. Suggest you
get ahold of some of the old Scientific American Amateur Scientist
columns (especially from the fifties and sixties) for ideas before you
decide on one. Also check the availability and cost of rebuild kits. I
got a brand new yet ancient (1965?) US government surplus one from a
dealer in PA some years back. Still in the original crate, with two
copies of mil-spec manuals sealed in foil, and with a new/old bottle
of pump oil.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
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