Vacuum chamber and pump question

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Jaruemalak

Well-Known Member
It looks like it would work fine, but it seems like a rather high investment if you only have a few molds to make. I've used a small hand vacuum pump (used for bleeding air from auto brake lines) to degass silicone for years and it works great. I paid about $20 US for it.
 

Canobi

Sr Member
RPF PREMIUM MEMBER
I agree, it would be fine, but only if your going to use it over and over. If you just need a few moulds done and that's it I would find a cheaper alternative.

A hand pump is one of them. However, it's possible to degassed without a chamber. Make a 1cm hole near the base of a large paper cup or equivolent and cover the hole with electrical tape. Mix the silicone and transfer into you cup with hole. Place the cup about about four to five foot above the mould and remove the tape. As the silicone falls it will stretch quite a bit and this forces the bubbles to pop on its way down to the mould box.
 

tgk

Active Member
Dude that is way too pricey, how about a paint bucket and a shop vac? You would need a piece of clear perspex and some rubber to create a seal at the top of the bucket. It's not much money and should work for your needs. Good luck
 

Canobi

Sr Member
RPF PREMIUM MEMBER
If you can find an empty second hand fire extinguisher and cut the top off, it'll make a good degassing chamber. It'll be a lot cheaper than buying one.

I'm getting to a point where I will be needing one too. After researching chambers, I just wasn't prepared to fork out the super high prices they want for one, so I decided to see if I could make a chamber for as little as possible. The only things I spent money on we're the pump @£200 (I will be using mine a lot) and fixtures for the chamber. I was donated a helium bottle after asking about (safer in magnitude than a butane bottle :lol) and proceeded to cut the top off.

Once that was done, I made a flange for it using JB Weld and trimmed before it had fully cured.



I used 100% silicone caulking for a gasket, and bought a 1" piece of acrylic as the lid.

I then made a work unit for the chamber and the pump out of a cast off chest of drawers.



So far the chamber has cost £80 which is a darn sight cheaper than the £600 for one of equivolent size.

I'm going to test it for leaks in the next couple of days and I'll let you know how it goes.
 

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Siliconeman

New Member
Hello! Thanks for your replies!
Actually, I will use the vacuum pump also for other purposes, so I can invest on it with no problem. The thing I need to know is wether this 1cfm single stage pump that I can see in this eBay offer is powerful enough to create over 28 mm/Hg vacuum?

Canobi, thanks for sharing you chamber building pics!
They really are expensive, anyone has good sources to get a small one decently priced, in europe?
 

Canobi

Sr Member
RPF PREMIUM MEMBER
Hey, no prob. Let me know if you don't find one, I'll see about making one for you instead.
 

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