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Pressure pot/Vacuum chamber etc

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Pressure pot/Vacuum chamber etc

Postby piggyv01 » Thu Jun 25, 2015 12:07 pm

Hello,
I'm attempting to make my own resin toys from original sculpts, however, after several tries it's become clear that I need some equipment. I'm having trouble working out what I need and where to source it (I'm in Australia). I know I need a pressure pot or vacuum chamber and an air compressor that will work with an air brush too. Can anyone offer any concrete info?
(the figures I'm making are roughly 6" high and 5" across at the most. I've been using Barnes Banana skin silicone for the mould and Barnes supercast and epoxyclear resins for the casts).
Thanks in advance.
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Re: Pressure pot/Vacuum chamber etc

Postby mangozac » Mon Jun 29, 2015 10:06 am

Super Cheap Auto carry the pressure pot, but it's normally quite pricey. They regularly have it on sale for around $120. You can get a compressor from them too - make sure it has at least a 20L tank.

Here in Oz vacuum pumps are most easily and economically sourced from ebay - make sure you get one with a flow rate of at least 5 CFM.

Reading the posts at the top of this subforum will give you some idea of how everything gets connected up and used ;)

Hope that help!
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Re: Pressure pot/Vacuum chamber etc

Postby piggyv01 » Wed Jul 01, 2015 11:48 am

Thank you so much for your reply.
I'm literally clueless about this stuff and research has only made it more confusing.
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Re: Pressure pot/Vacuum chamber etc

Postby piggyv01 » Wed Jul 01, 2015 2:01 pm

I've been looking through the other forums and posts. Regarding the Supercheap Auto pressure pot*, will it need to be modified beyond removing the spray gun and attaching the appropriate hoses? I'm not too handy or technically minded, you see.

*http://www.supercheapauto.com.au/online-store/products/Blackridge-Air-Spray-Gun-Siphon-Feed-10-Litre.aspx?pid=156470#Recommendations
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Re: Pressure pot/Vacuum chamber etc

Postby mangozac » Thu Jul 02, 2015 2:03 pm

Yeah the Super Cheap pot converts pretty easily. The hardest thing is unscrewing the suction tube attached to the bottom of the lid - it's screwed in and secured with adhesive so you really need a vice or something similar to remove it.

The non-sale price is quite high though - either wait until they're on sale or find one online (ebay used to have plenty of cheap ones but it doesn't look like it any more).
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Re: Pressure pot/Vacuum chamber etc

Postby piggyv01 » Mon Jul 06, 2015 5:14 pm

Thanks again for your reply. I found one on ebay for $150 with free shipping. I'm pretty wary of converting it as I'm not that handy but i'll have to give it a go. Now I need a compressor and airbrush and studio.
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Re: Pressure pot/Vacuum chamber etc

Postby RageofAchilles » Mon Jul 06, 2015 6:47 pm

Converting a pot is the easy part, I just sheared off the paint tube with an angle grinder and then epoxied a bend where it had been so that air enters the pot interior sideways instead of straight down. ;)
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Re: Pressure pot/Vacuum chamber etc

Postby mangozac » Tue Jul 07, 2015 7:35 am

RageofAchilles wrote:Converting a pot is the easy part, I just sheared off the paint tube with an angle grinder and then epoxied a bend where it had been so that air enters the pot interior sideways instead of straight down. ;)

I still haven't gotten around to putting a bend where my air enters! I just slowly increase the flow rate over 10 or so seconds to minimise the blast effect. I will stick a tee in there one day ;)
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Re: Pressure pot/Vacuum chamber etc

Postby AdamMarosi » Mon Nov 09, 2015 3:32 pm

I am often asked if a vacuum chamber or a pressure pot is required in the fine art of mold making and casting. As with so many answers in life, a “yes” or “no” answer is not possible without first learning more information about the project. Except for water clear resin such as AquaClear resin, where tiny air bubbles will obscure the clarity of a piece, and such equipment is a must, my answer most often is, “It all depends.” That is unsatisfactory, I know.
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Re: Pressure pot/Vacuum chamber etc

Postby piggyv01 » Fri Jan 08, 2016 4:50 pm

Hello. I had a brief hiatus sorting all this out, but a friend gave me a Blackridge 10l pressure pot for Christmas and i'm now sorting the compressor out.
Which do you suppose would be more suitable?

Blackridge Air Compressor Direct Drive 2.0HP - 95LPM 21L capacity

Blackridge Air Compressor Direct Drive 2.5HP - 120LPM 40L capacity
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Re: Pressure pot/Vacuum chamber etc

Postby Fleafa » Sat Jan 09, 2016 7:07 pm

Both are acceptable, with the lower capacity being double that of your pot (remember the pressure will equalise between them). The second option will run less frequently though.
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Re: Pressure pot/Vacuum chamber etc

Postby piggyv01 » Fri Jun 03, 2016 2:54 pm

Hello again. Previously, someone was kind enough to direct me to some diagrams regarding pressure pot modifications but I can no longer find that link or the sub forum it was in...if that person reads this, can you link me up again please. Thanks in advance.
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Re: Pressure pot/Vacuum chamber etc

Postby Fleafa » Sat Jun 04, 2016 4:13 am

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Re: Pressure pot/Vacuum chamber etc

Postby piggyv01 » Sat Jun 10, 2017 1:59 pm

Hello again. It's been a long time and slow going (i've mostly been focused on sculpting) but I finally rigged up the pot and took it for a run....however.
I've ruined two moulds, which is a shame as the sculpts didn't survive the moulding process.
The first I took up to 55psi because I'd read/seen in numerous places people say 60psi for resin casting, but I didn't want to push it. The cast came out with lots of bubble like protuberances all over it, which were reflected in the mould like tiny holes. They hadn't been there originally. The second I didn't exceed 40psi but the same thing has happened. Any ideas?
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Re: Pressure pot/Vacuum chamber etc

Postby robn1 » Sat Jun 10, 2017 5:38 pm

piggyv01 wrote:Hello again. It's been a long time and slow going (i've mostly been focused on sculpting) but I finally rigged up the pot and took it for a run....however.
I've ruined two moulds, which is a shame as the sculpts didn't survive the moulding process.
The first I took up to 55psi because I'd read/seen in numerous places people say 60psi for resin casting, but I didn't want to push it. The cast came out with lots of bubble like protuberances all over it, which were reflected in the mould like tiny holes. They hadn't been there originally. The second I didn't exceed 40psi but the same thing has happened. Any ideas?


It would help to see some pics, but from your description I'd say you have bubbles in your mold (air bubbles trapped in the silicone as it cured). These gaps collapse under pressure causing the resin to form raised bumps. The silicone needs to be deaired in a vac chamber. The mold silicone could also be cured under pressure to eliminate bubbles which is how I do mine, but your pattern/sculpt has to be able to withstand pressure.
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