Homemade Vacuum Pump

[Sam's Workshop Diary]

I build this vacuum pump out of an old fridge compressor.
I want to use it to stabilize wood with oil or resin.

[Toolmaker51]

Count me interested. Will multiple compressors pull down larger chamber through a manifold?. I have a huge bell jar approximately 24" x 30"... would double as power for a vacuum chuck.

[Sam's Workshop Diary]

Count me interested. Will multiple compressors pull down larger chamber through a manifold?. I have a huge bell jar approximately 24" x 30"... would double as power for a vacuum chuck.

I think it's possible to use more pumps for a better vacuum, when you have a large chamber.

[tonyfoale]

I think it's possible to use more pumps for a better vacuum, when you have a large chamber.

More pumps in parallel will not create a better vacumn but they will create the same vacumn quicker and so will have an advantage when sucking down a large container.
If you have good good compressed air supply you can buy or make a venturi vacumn pump which can provide a surprisingly good suck.

[Toolmaker51]

More pumps in parallel will not create a better vacumn but they will create the same vacumn quicker and so will have an advantage when sucking down a large container.
If you have good good compressed air supply you can buy or make a venturi vacumn pump which can provide a surprisingly good suck.

Hmmm, running a vacuum port [eductor] hadn't occurred to me. The multiple pumps address volume in what seem economical fashion....Thinking now to pull it down with venturi [a little harder to control], and maintain it with a pump.
Until I finish the lid [bell jar] and jar hoisting sling, the seal is a question mark. Initial plan positioned it open end up, too high to reach down into, and quite heavy. bought lab grade bell at auction long ago, about 14mm wall. Definitely not the thin terrarium or display variety. Now, closed end up, vessels seat on an easy flat surface.
Per the usual, design process [skilled cobble-up] just as fun a real build. BTW, lab bells this size are ~$750, displays ~$50...crackerbox thin. So, extra care is rewarding. The sling is [might be] a stretched bicycle inner tube, three long webbing legs, terminated with a ring.

[tonyfoale]

Hmmm, running a vacuum port [eductor] hadn't occurred to me. The multiple pumps address volume in what seem economical fashion....Thinking now to pull it down with venturi [a little harder to control], and maintain it with a pump.

Here is my venturi thingy.

Click thumbnail for full size images.


Here is the power brake vacumn pump to compensate for the lack of manifold vacumn in diesel engines. This was driven off the end of the camshaft, so around 3000 rpm should work really well. They have a good flow rate and suction but I have no real data.

[PJs]

Hmmm, running a vacuum port [eductor] hadn't occurred to me. The multiple pumps address volume in what seem economical fashion....Thinking now to pull it down with venturi [a little harder to control], and maintain it with a pump.
Until I finish the lid [bell jar] and jar hoisting sling, the seal is a question mark. Initial plan positioned it open end up, too high to reach down into, and quite heavy. bought lab grade bell at auction long ago, about 14mm wall. Definitely not the thin terrarium or display variety. Now, closed end up, vessels seat on an easy flat surface.
Per the usual, design process [skilled cobble-up] just as fun a real build. BTW, lab bells this size are ~$750, displays ~$50...crackerbox thin. So, extra care is rewarding. The sling is [might be] a stretched bicycle inner tube, three long webbing legs, terminated with a ring.

TM51, I am assuming you will be using the Humongous bell jar inverted?

Years ago in my life in cryogenic refrigeration systems I built a Show unit with difficult design parameters that required a 10" bell jar (Quartz/Borosilicate) to handle the vacuum and discharge pressures/temps we were working with. I used a 1/3hp refrigeration compressor for the cryogenic portion and my plate for keeping the weight down was made from 1/2" 7075-T6 plate I had anodized and then turned the seal portion to a surface finish of about 16 and the lip helped keep the jar on when atmosphere was present. I had to have the bell jar shortened and reground and bought a vacuum seal for it also. We used pure silicone vacuum grease around the shop for sealing and it worked fine. The unit could pull about .1 millitorr (3.9e-6 in.mg) and cycle back to atmosphere in about 4 minutes on that bell jar...cryogenically.

A system of your Whataburger size will take awhile to pump down even with a big compressor...1/2-1hp-something with a larger than 1/4" inlet. Our big units used 10hp 6 cyl. Carlyle's (06d) and our smallest used a 1/3hp Tecumseh's. Personally I wouldn't even consider a venturi system...your compressor may have a conniption fit and suffer a seizure...let alone the mind numbing noise generated.

Be sure your bell is in good condition and I would recommend a needle valve to vent the system...slowly. Dangerous implosion hazards otherwise. I don't know if anybody but old timers know what happens when you shoot a TV picture tube with a 22...similar attributes but 14mm quartz is sharp.

Sams Workshop Diary; Nice clean build, well done! Please be careful using off the shelf glass jars, they can become stressed over time and let go unexpectedly.


PJ

[tonyfoale]

Some years ago I used a Fridge compressor as a vacumn pump. I used it to suck air out of epoxy and polyester resin as well shock absorber oil.
Then I picked up a real vacumn pump for almost free at a flea market so the Fridge based one just sits on a shelf now but it worked fine when I used it.
Some people do the opposite and use them as compressors.

[Toolmaker51]

Some years ago I used a Fridge compressor as a vacumn pump. I used it to suck air out of epoxy and polyester resin as well shock absorber oil.
Then I picked up a real vacumn pump for almost free at a flea market so the Fridge based one just sits on a shelf now but it worked fine when I used it.
Some people do the opposite and use them as compressors.

I got a big kick out of the spot-painter and his very mechanical adaptation, especially the former tire as air reservoir.
Yessir; vacuum that is my intention. I'm thinking a manifold with ball/ spring check valves would allow multiple pumps to pull down large bell jar without pulling on other pumps. Project is impregnating hardwood spacers and pistol grips.

[suther51]

I do not know the max vacuum but I have used automotive a.c. pumps to create vacuum. Lots of them in junk yards.
Eric