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Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Ash Small wrote ...
A disc of porcelain may prove to be more suitable, depending on the application.
This is what im thinking.
The obround is the outside perimeter of the porcelain, 3/8" thick. The inside rectangle with round corners is the hole through the pressure vessel. There are four 10-24 all-thread studs, three 1/4-20, and they all have those Faston ring terminals. it would be attatched to the pressure vessel via PMMA epoxy.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Patrick wrote ...
Ash Small wrote ...
A disc of porcelain may prove to be more suitable, depending on the application.
The obround is the outside perimeter of the porcelain, 3/8" thick. The inside rectangle with round corners is the hole through the pressure vessel. There are four 10-24 all-thread studs, three 1/4-20, and they all have those Faston ring terminals. it would be attatched to the pressure vessel via PMMA epoxy.
Are you going to share the rest of the details about this project with us?
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Ash Small wrote ...
Patrick wrote ...
Ash Small wrote ...
A disc of porcelain may prove to be more suitable, depending on the application.
The obround is the outside perimeter of the porcelain, 3/8" thick. The inside rectangle with round corners is the hole through the pressure vessel. There are four 10-24 all-thread studs, three 1/4-20, and they all have those Faston ring terminals. it would be attatched to the pressure vessel via PMMA epoxy.
Are you going to share the rest of the details about this project with us?
Registered Member #3610
Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506
Conundrum wrote ...
Handy for homemade fusors, etc.
Can someone PLEASE tell me where I can fund a decent vacuum pump for less than £50 which works well enough for basic demonstration of poissors etc (1000 Torr or so?)
Thanks.. -A
I got my Welch Duo-Seal pump for a dollar on ebay several years back. Of course it was another $50 to ship (HEAVY!!) and looked like it had spent a year on the bottom of the ocean. It cleaned up real nice after scrubbing inside and out, $40 worth of new seals and fresh oil and eventually got down to 2 microns.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
James wrote ...
Conundrum wrote ...
Handy for homemade fusors, etc.
Can someone PLEASE tell me where I can fund a decent vacuum pump for less than £50 which works well enough for basic demonstration of poissors etc (1000 Torr or so?)
Thanks.. -A
I got my Welch Duo-Seal pump for a dollar on ebay several years back. Of course it was another $50 to ship (HEAVY!!) and looked like it had spent a year on the bottom of the ocean. It cleaned up real nice after scrubbing inside and out, $40 worth of new seals and fresh oil and eventually got down to 2 microns.
Ive used this exact same pump at shasta college, worked real well when all the old parts were replaced.
Registered Member #3429
Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288
James wrote ...
I got my Welch Duo-Seal pump for a dollar on ebay several years back. Of course it was another $50 to ship (HEAVY!!) and looked like it had spent a year on the bottom of the ocean. It cleaned up real nice after scrubbing inside and out, $40 worth of new seals and fresh oil and eventually got down to 2 microns.
Looks like you did a great job cleaning it up and repainting it. I own 2 Welch Duo-Seal pumps (model 1397) that I use for my X-ray tubehead repair business. They too would suck down to 2 or 3 microns if the pumps were not connected to any other vacuum components. But when connected to my large bell jars with all the associated plumbing, I'm lucky to pull less than 20 microns (on a good day!).
Grenadier -- Excellent idea for mini vacuum feedthroughs! I'm guessing they would be good to about 2KV or so, but you might be able to use them with much higher voltage if you glob lots of silicone or non-conductive Epoxy cement around the conductors.
Registered Member #3429
Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288
magnet18 wrote ...
So how good of a vacuum can a fridge compressor make?
A fridge compressor is not a very good vacuum pump. At best you can get some suction that might be good enough for drying insulating oil (over a LONG time period) but is otherwise not much good for anything else. The problem with a fridge compressor is they are piston pumps, and piston pumps have "head space", which severely limits their ability to pull a vacuum. Head space is the volume of air that remains within the cylinder when the piston is at top-dead-center. Most serious vacuum pumps use rotating carbon or phenolic vanes for producing a vacuum, and serious vacuum pumps used for low pressures are two-stage pumps (like the Welch Duo-Seal series of pumps).
Here is a very good techinical reference about basic vacuum technology and equipment. There are other good tutorials on the web about vacuum technology, and you just have to search for them.
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MacGyver Vacuum feedthrough
