Picture of Diffusion Vacuum Pump
Please look up the definition of a Diffusion Vacuum Pump before continuing!

This pump is made from readily available materials and has been shown to achieve a .022 TORR vacuum!!!!

Use extreme caution when working with vacuum

This pump needs a "Roughing" pump to get down to a near vacuum then it will work as described.
No a refrigerator compressor will not work as a "Roughing" Pump for this
No a vacuum cleaner will not work either!

You will need a refrigeration service type pump for the "Roughing" of the vacuum.

Yes you may have to go to IKEA to get some of the parts!

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Step 1: Materials

Picture of Materials
You will need a stainless steel tube (I used an exhaust pipe section)
Some 1/4 inch copper tube and
stainless steel flat sections.

I found that the local scrap yard had lots of stainless steel parts. Selecting the right few took a couple of trips.

You will also need to know how to braze. I used stainless brazing rod for joining all parts.

I used a stainless 2.75 od exhaust pipe adapter for the body. Some scrap stainless flats for the ends.

All cutting was done with a Dremel and cut-off abrasive wheel.

Several Ikea stainless cups were sacrificed for this build!

Step 2: Lower end

Picture of lower end
The base was a scrap cut stainless round. the edged were smoothed and a 10x32 nut was brazed in the center.
This was then brazed to the center of the exhaust pipe.

a 1/2 inch hole was drilled into the exhaust pipe for a vacuum port. This was about 1 inch from the bottom edge.

Thanks for this !!!!

brian50031 year ago

Thank you...I finally understand how a diffusion pump works. Been looking at these awhile and scratching my head. You might link to this swf with an animated cross section of how it works on a molecular level.


pratus2 years ago
I'm curious what sort of torch you are using? As well as the rough total amount you ended up spending? Thanks! Very cool!
Random_Canadian (author)  pratus2 years ago
The torch is a Smith Little Torch. Quite small for this job but I used what I had.

The Stainless metal was $1 per pound at my local scrap yard "Federal Metals Calgary". The retail parts were under $10 and the tubing was purchased over 10 years ago for about $20.
eelco_g2 years ago
I'm a bit lost. Some background, a working principle and a schematic would make this a great instructable. Also, could you explain a bit more about the construction? For example in step 6, where does the copper coil come from? It's just there all of a sudden without explanation. Thanks.
Random_Canadian (author)  eelco_g2 years ago
Sorry about that. I got in the zone with the build. The copper tube is a gravity feed cooling apparatus. Wrap 3-4 coils of copper tube around the body of the pump. Braze this tot he body. Water is gravity fed in a steady drip to facilitate cooling of the pump body and allow the pump to cool the heated oil.
gcr1002 years ago
You win a follower with this pump i am making my own but i have a question can i use 2 fridge compresors in series as a mechanical pum i know that the ideal pump is the rotary vanes one, but here in Mexico they are really expensive i know that one can get a vacuum of 100mbar
rimar20003 years ago
Awesome project!

Surely you can aluminize using this vaccum pump, isn't?
Random_Canadian (author)  rimar20003 years ago

That is definitely one of the plans!
I envy you a bit... Is there something like good envy?
Yep, called "admiration" and "inspiration".