Re: Cheap vacuum pump

To: "'Tesla List'" <tesla-at-poodle.pupman-dot-com>
Subject: Re: Cheap vacuum pump
From: Tesla List <tesla-at-stic-dot-net>
Date: Sat, 1 Nov 1997 00:23:45 -0600
Approved: tesla-at-stic-dot-net

From: 	Julian Green[SMTP:julian-at-kbss.bt.co.uk]
Sent: 	Friday, October 31, 1997 8:59 AM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: Cheap vacuum pump

> From: 	ghunter-at-mail.enterprise-dot-net[SMTP:ghunter-at-mail.enterprise-dot-net]
> Sent: 	Friday, October 31, 1997 9:15 AM
> To: 	tesla-at-pupman-dot-com
> Subject: 	Cheap vacuum pump
> 
> Years ago I read an article in an ancient volume of "Scientific
> American" magazine.  The author described how to build a vacuum pump
> using a rotary compressor from a discarded refridgerator.  He vented
> the freon, drained out the old oil, & refilled it with vacuum pump
> oil.  Of course, he had to solder on a few pieces of copper tube for
> hookup.  He used it to make a homebrew x-ray tube, so it must've
> pulled a pretty hard vacuum!  For poor coilers who can't afford a real
> pump, this sounds like a cheap & interesting experiment that could
> lead to better poly caps.  When I get back to the US I plan to try it 
> myself.
> 
> Greg
> 
> 
> 
> 
I can second that, go down to the local scrap yard with a hack saw, find a fridge
and remove the pump.   Dont forget to get the motor starter gear.

The need for vacuum oil is not as necessary as it sounds, and is quite expensive.
The oil to use is a light grade oil (like transformer machine oil) but it needs 
to be de-gased.  I believe this can be done by boiling it.

If you are in doubt about the oil then use it anyway, and perform a vacuum test
on the oil.  Put some in a glass jar (not a big one else implosion may result)
and connect it up to the vacuum pump.   Evacuate the jar and if the oil fizzes up
its not de-gassed and will more boiling.

If you use the same oil in your cap and vacuum pump then it does not matter if 
some of the coil from the cap finds its way into the vacuum pump.  This happened
to me when I did my caps as air from the cap generated so many bubbles
that it filled the cavity at the top of the cap and into the pump it went.

Do not put motor oil in the pump it is too viscous and will prevent the pump 
starting when it is cold. 

Julian Green