Vacuum pump/mold materials

I picked up this vacuum pump at an estate sale. Can I create a vacuum pump for mold material/de-gassing by attaching it to a acrylic top and bucket?



If so, where can I get the parts?


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Are there any other specs? Ideally you want to know cfm.

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Here's a screenshot I found online. I bought this at an estate sale for $10. Just wondering if it will work or if I should unload it:




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Going by the specs (and I have no idea regarding that particular pump), it says it pulls 20" Mercury. To outgas silicone or resin, you're going to need a full 29" pull. It starts to outgas around 27 or so but doesn't really get going until the full struggling vacuum of 29.

As I understand it, a vacuum pump (at least mine) needs an oil reservoir to achieve vacuum. And you need to maintain the oil's integrity from moisture so a sight glass is usually incorporated.

As far as a chamber, you can use an existing vessel, but it's got to be sturdy, not just a bucket. More like a heavy stock pot or pressure pot tank. Anything even remotely thin walled will collapse. Remember, water 'boils' at room temperature under vacuum, you're talking about significant forces. You acrylic cover needs to be thick, not a sheet you'd get at Home Depot. I use a quarter of an inch thick Plexi plate with an aluminum frame and a neopreme gasket.

If you want to test the pump, grab a vacuum gauge (you'll need one anyway) and hook it up. If it pulls 29", you're in. If not, you may still be able to use it with a vacu forming setup.

All good information but also remember that the size of the chamber also affects the results. You have a potlife to the product your using. Ideally you want to reach a full vacuum in less than a minute.
Like it cool that you picked this up for the price you paid, but you could be up for a lot more if you don't understand how this works.

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cavx said:

All good information but also remember that the size of the chamber also affects the results. You have a potlife to the product your using. Ideally you want to reach a full vacuum in less than a minute.
Like it cool that you picked this up for the price you paid, but you could be up for a lot more if you don't understand how this works.

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Click to expand...

I think I'll unload this online and pick up a professional set-up instead. Thanks for the info!!


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I think you will enjoy molding and casting more when you have the tools that are made to do the job.

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I agree fully, You shouldn't need to be chasing you tail setting up gear.

That said, for a small chamber I use for production runs of scale figure, I have an affordable setup using an old Circulon Stock Pot and a HVAC vacuum pump. The Pot is a heavy walled anodized aluminum about a gallon in size and the pump reaches 29 inches in less than 30 seconds. Running resin with a 7 minute pot life I can mix, pour and achieve vacuum and slow release in 3-4 minutes total. Casts are bubble free. With silicone, the pot life is no issue so I can work at leisure, pull for three minutes, pour, repull.

Keep in mind that's all for small stuff, if you plan on doing large 1:1 heads, you'll need much larger gear. A good rule of thumb is give yourself about 4 times them volume for expansion.

It is actually pretty amazing with what can be done in those smaller 1 gallon chambers. Like you said, for small projects. Having said that, even though my chamber is 30 litres, the biggest bucket I can fit inside is 5 litre, so I am only ever mixing 2KG of silicone max anyway. If a job needs more, it multiple pours.

Yeah, my days of big projects are long gone. It's small and manageable for me now. These four 1/16 heads are in total 15ml of resin and the silicone for the mold was 40ml. I can run them in three minutes and cycle the mold every hour on the hour.