New member wanting a vacuum chamber

[Fleafa]

Unfortunately the Royal Mail (& Parcelforce) have some frustrating rules on fluids. Oil shouldn't be too hard to come by.

[rattrap]

Well, it's been a good day for equipment purchasing today. We went to collect the pressure pot, and got that. While we were there, I got a call from the seller who had the Sealey compressor to tell me she had sold it. So while we were there we asked if they had any deals on compressors. They offered us a ex-rental one, 2 HP, which was like new, for half the price of a new one so we bought that as well. We also asked for some oil for the vacuum pump which they didn't have. They gave us directions to another place in Hull which they thought would have some. Got there and they didn't have the correct oil, but they mixed some for us to the correct viscoscity, and gave us that free!
The vacuum pump is a US one (CPS Pro-Set) and the fittings are different so I am going out again tomorrow to try and find the correct fitting so it will connect to the pressure pot.
All in all, a pretty good day.......

[KoD]

Some great info here, and clearly a good amount of research by the OP! Cheers.

I had a look around, but couldn't find a thread related to using a pressure pot as a vacuum chamber, and what would be required for the conversion - if anything. So i do not mean to hijack this thread (someone who might know of another thread that can provide a link would be great), but I feel the info would be useful here also.

This is the pot I use - its a standard 10l paint pot and has been working well, but I want to hook up a vacuum pump so I can use it as a vacuum chamber also - not being able to see inside is of little concern to me.

You'll notice that I still have the paint gun attached as I couldn't easily find the correct fittings to close it off.


I'm guessing I need to rig up dual dials, one for the pressure, and one for the vacuum ... right?

This is the pump I am looking at (its 9cfm, dual stage, 1hp) >

Advice or links to other threads would be well appreciated.

Looking forward to seeing what the OP rigs up.

Cheers

[mangozac]

Viv that pump on ebay is perfect - very similar to what I run

I discuss my pressure and vacuum casting setup over , but I've got a slightly overcomplicated connection system due to just using what I had on hand!

Other than considerations with the gauges there's nothing special required to use the pressure pot for vacuum. I have separate valves on the pressure and vacuum gauges, but if I were to build another pot I'd try to pick up a 2-in-1 vacuum and pressure gauge, as that would be a lot more elegant. The vacuum scale on such gauges is only short and thus doesn't provide very fine readability, but I don't think it matters to much - I vacuum based on time rather than level of vacuum.

What's the gas bottle for?

[KoD]

[mangozac]

[rattrap]

The pressure pot I got yesterday is exactly the same as KoD's one.

Managed to get the correct fitting for the pipe today. I tried everywhere this morning, hardware stores, plumbing merchants, none of them had the correct thread for it. I ended up getting it from an air conditioning company locally. If anyone ever needs to renew theirs, I suggest thats where they go. It is an ACME thread which apparantly is only used on air con units.

[KoD]

[rattrap]

This company is in East Yorkshire.
When I went yesterday I was lucky because the reception was closed but the workshop was open. I had a word with one of the guys in the workshop, showed him the pump, and told him what I was wanting to do. He gave me an old pipe with the 1/4 inch fitting on, but he said the pipe may be leaking. I don't want to get him into trouble because he gave me it for free, so If you want, I can try and get you one too.
Are you in the UK?

[KoD]

[rattrap]

Just been messing around connecting the hose onto the pump tonight. Turned it on and felt what the suction was like on the end of the pipe. I was quite surprised on how little suction there was. I put my finger on the end, and there is vacuum there but not that it would want to suck my finger in if you know what I mean.
Is this normal with a pump of 6.2 CFM ???

[mangozac]

Yeah if I remember correctly it won't feel that strong. It may be that your skin doesn't form that good a seal on the pipe?

[Fleafa]

If that pressure pot is the same as mine (except painted black), it has a mixture of fittings standards:


I ended up doing this:




I only use that lid for pressure. I had a friend who works for Rolls Royce knock me up an alu lid with a plastic window. That's a little gunked up now, can't see very well, so I'm going to get a polycarbonate (lexan) sheet and make a new lid. I like to watch the degassing as I can better judge when to cut the vacuum. The gauge is pretty much irrelevant, as I hold vacuum on silicone until the big bubbles collapse and on resin until it froths. Helps me know I'm actually pulling air out though!

[rattrap]

Got the Lexan polycarbonate top today, but struggling to find the rubber gasket to stick on it. Does anyone know the best place to get it?
Looked on ebay tonight, but unsure what I am looking for.
Thank you in advance...

[rattrap]

Well, so far I have got just about everything now. Really looking forward to building it all up this weekend and getting cracking.
I know there is going to be lots of cock up's and swearing in the future, but I believe that the more mistakes you make, the more you learn. I know am entering a big learning curve, but looking forward to the ride.
Many thanks to all who have helped me along the way so far,and please.....WISH ME LUCK!!!