New to casting, many questions

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J

jbmauser

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Joined
Nov 16, 2008
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Roanoke, VA
I spent time in the library but one important question seems to remain unanswered. I am going to build a pressure pot out of this old pressure cooker. the lid is captured and is sealed with up pressure. I read where one guy runs pressure to 40# the guy who sells cactus juice talked about making a blank from flowers and running up to 80# and still getting some small bubbles.

what is the common or normal working pressure?
Will a pancake air compressor do the trick?
How long do you maintain pressure?
Any safety tips like run a long hose and put it outside?
Not looking to add any more excitement to my life, just cast a few blanks!


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DO NOT USE A PRESSURE COOKER!! or you will add lots of (dangerous) excitement to your life.
What resin do you plan to use. Some cure in 30 minutes and others take several hours.
Small volume air compressors can pressurize small volume tanks and of course your compressor must be able to generate the same pressure as the pressure you want to use to cast. I cast polyester resin and cast at 60 psi but those who cast with alumilite use a higher pressure.

You will find lots of casting info on you tube or searching via google.
Don
 
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I will jump in also and do not recommend you using that pot. Not designed for what we do.

Also taking another step back even further, what is it that you are casting??? Many times pressure is not needed. Also what resin are you using>??? You say a few blanks, if you are not going to take it seriously then why not ask someone to cast for you or I bet with all the people casting today that maybe someone already does what you want. There is an expense when casting your own blanks because there is a large learning curve too to go along with the equipment.:) just my opinion.
 
I am not sure what I will cast, stamps, perhaps some watch pieces, pine cone and I have a shed snake skin somewhere. Steam punk pens are fun, I have some ideas that I think will require pressure. I bought a kit with resin corks, led shot etc and have not given it a try. I think this small thick brick of a container will do the job at modest pressure. I plan on a field proof test, as in place it in the field and run it up to high pressure and let is sit for time. I am not foolish but I also know that a design with a oversize lid needs to have a catastrophic metal failure to breech. That is why I asked what normal pressure is used. I plan on using it as a vacuum pot as well. The idea of stabilizing blanks has some interest. I don't think I need to see the bubbles etc. It is interesting to see that the dental pressure pots that sell for big bucks are the same design as modern household pressure cookers. This little pot does have a hard blow out plug. I have no idea what it's fail point is. Ergo the field test.
 
I have an old pressure cooker that I'm saving to make a vacuum drying chamber with. It has a pressure gauge that red lines before 20 psi and a working pressure of 10 to 15 max. I wouldn't go any high than that.

If you really insist on playing with higher pressures test the pot with it filled to the brim with water to lessen the explosive forces should it let go.
 
jbmauser said:
I am not sure what I will cast, stamps, perhaps some watch pieces, pine cone and I have a shed snake skin somewhere. Steam punk pens are fun, I have some ideas that I think will require pressure. I bought a kit with resin corks, led shot etc and have not given it a try. I think this small thick brick of a container will do the job at modest pressure. I plan on a field proof test, as in place it in the field and run it up to high pressure and let is sit for time. I am not foolish but I also know that a design with a oversize lid needs to have a catastrophic metal failure to breech. That is why I asked what normal pressure is used. I plan on using it as a vacuum pot as well. The idea of stabilizing blanks has some interest. I don't think I need to see the bubbles etc. It is interesting to see that the dental pressure pots that sell for big bucks are the same design as modern household pressure cookers. This little pot does have a hard blow out plug. I have no idea what it's fail point is. Ergo the field test.
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Good luck. Just because it holds the first time if it does, does not mean it is good to go. Internal cracks or failure may go unnoticed.
 
For a $80 you can get a new pressure pot from the local Harbor Freight. Another $20 for retro-fitted parts and you have a much more safe and conventional system that will get you safely to the pressures you're going to need for castings.
 
I have to agree with everyone else here. Don't use a modified pressure cooking pot. Also, from what I see you're wanting to cast, you don't even need a pressure pot.
 
I don't use a pressure pot at all at least not until I can learn more on it and be able to afford to get the tools needed to use it. I cast alumilite and so far I have not had any problems with any bubbles except for the pine cone blank I casted, but that is another story. I wouldn't use a pressure cooker unless you plan on cooking some ribs or a good roast under pressure. LOL! Certainly not for casting any blanks. Good luck with what ever you do.. Fay
 
Buy a used Binks or Devilbiss pressure pot that is rated for at least 80 psi.Saver then trying to rig up some haphazard device.In the overall cost of casting the expense is not that great.Alumilite runs $170 for 2 gallons and then you still need various dyes and mica powders.
 
I use the HF pot, with a 60psi pressure relief valve. (the one that came with it wouldn't hold 10!)
 
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