can i ??

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make a pressure pot from a pressure cooker?? like you use to cook a roost in??  superstock

[Excrewchief]

It is very simple the hard part is finding a good pressure pot. Presto seems to make the best that we have found so far. ( the seals hold up the best ) the others work but the seals are always leaking ... I have found some at goodwill the last one i payed $6.00 and it works great greg has got some from ebay. Take your time and you will find them if your in a big hurry its makes them hard to find never fails. They make different sizes i think i use 6 qt for most casting. Then the larger ones for the bodies. Iam moving right now as soon as i can get to things i will post pictures.

Once you get the pot you have to remove the air bleed on top. Some are 1/8 " and some are 1/4" pipe thread install a pipe nipple with a T gauges ,
And some on of valves a pressure regulator. It really is simple once you see the picture. Ill try to get it in the next two days.
Your also going to need air 60 lbs works the best that i have found i have read lots on storys and therorys about how much pressure to use from 45 and up to crush the air bubbles or push them out etc etc . And i will stay at 58 to 60 myself. Keep searching and asking and we will do our best to answer all for you .thanks for asking Rocky

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thanks rocky..will be waiting for pictures an info..  superstock

[Excrewchief]

I also asked greg to see if he had any pictures to post . He is looking one of us will get something up very soon .
BTW what are you trying to mold and cast.

You will find that two piece molds with a pressure pot make some real nice parts but you may find that you have air bubbles that you did not know you had in your molds. If you have any friends that do a/c work see if they have any old vacuum pumps laying around then you can build a vacuum chamber to get the air out of the molds. The detail on small parts will amaze you how nice the parts start looking. If you hunt and make you own equipment it is not that pricey. Greg has bought some very pricy equipment that does not work as good as some that we have made. Keep your eyes and mind open you will be amazed at what you can build. Thanks Rocky

[superstock]

rocky..wanting to do a 2 piece mold of a body..will start with a small hotwheels body..donot want to waist to much silicone,experamiting with it..just trying to get what I need to do it..  too cold to try it now in my  unheated garage (28 deg. to 41 deg.)..want to do a 1/24 or 1/25 scale body when I get it worked out..hope you or greg find pictures of a converted pressure cooker??  maybe you or greg will show a 2 piece mold being made by summer time(warmer weather) thanks for any help..  superstock

[Mastercaster]

Here are two Presto pressure cookers I turned into pressure pots.  These are the best ones to have.  One is a 6 quart model number A617A and one is a 4 quart model number A403A.  I have had these since I started casting and they have never failed me.  The thread in the center is 1/8 pipe thread.  You could drill it out to 1/4 inch and use all 1/4 plumbing.  I chose to purchase a 1/4 X 1/8 bushing and close 1/8 nipple and then went all 1/4 IN. plumbing from there.  Ace hardware sells ball valves that typically have shorter handles, I buy them.  You could just cut handles off if you want to.  I have poured a layer of silicone and then some resin over that in one.  This makes them bottom heavy so they are more stable setting on a table.  The air line can be heavy and cause the pot to tip or you can stumble into the airline while working and cause it to be easily pulled off the work surface.  Remember when you are making any molds that they will fit inside the pot once finished.  Your first purchase might be a 6 quart one.  Most body molds will fit in it.  It is about 9.5 inches in diameter on the inside.  Most of my body molds are in the 8 inch range.  If your mold is too large you could cut the corners off to make it fit.  There is a vent in the lid that I blob silicone over and once cured it won't leak.  60 PSI is the magic number to crush bubbles in resin.  More pressure may cause more harm than good.  Regulators can be a real pain as they might start leaking around the adjustment handle.

[Excrewchief]

I just found a very good vidio on how to make a vacuum chamber on you tube. I'll post it here its also posted under links . Enjoy

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rocky...what is the difference in vacuuming an pressuring??superstock

[Excrewchief]

Vacuuming. Is when you vacuum down the silicone before you pour it into the mold. What it does water boils at apx 18 to 19 inches of vacuum air has moisture in it so by vacuuming. Down the silicone it removes the air bubbles most you can not even see it kind of like when you pour a soda in to a glass you see all the millions of little fizzy type bubbles . Alot of times if you make a mold and it looks real nice then you do the resin pour when you remove the part it will look fuzzy.
That is the microscopic air bubbles that I said you can't even see.then if you add pressure to the resin casting it will open all the holes up and they will fill with resin. They also can be alot bigger and just makes your casting look real bad .
Now in Theory when you add pressure to the mold after you add the resin it will crush the bubbles I have heard every pressure that you can think of all I can say is I can see a big difference when I run around 60 to 65 pounds of air pressure. There is a guy that makes you tube vidios that I watch once in a great while. He sayed the the lower his pressure is the better his parts look. If that's the case why use pressure at all. He says that his parts look fuzzy when he has more pressure . All I can say is he is not vacuuming his silicone down before he pours the mold or if he is he's not doing it correctly just because you vac it does not mean your doing it right. It depends alot on how much you mix and how hard you stir it. If you go smooth and slow you will mix in less air then If have a drill at 3000 rpm whiping air in to the mix. So the best way to vac is have a vac chamber that has a clear top and watch the air bubbles when there gone your good to go . Again how good is your vac pump is the vac chamber sealed proper if you have a pen hole it will never pull a full vacuum. Test it pull a vacuum shut it of all valves closed and wait five minutes does it still have vacuum. If not why ? If it's real quiet you can hear the leak run your hand around it sometimes you can hear it change or spray it with water when you hit the spot you'll know that should explaned most of what you need now and if not I am sure I will hear . That ok that is why I started this forum and remember you will learn every day I know I do . And the more you learn and understand the easyer it is when you have a problem. I still get molds that I have problems with. Sometimes I have to sit back and do some serious thinking. Sometimes I just have to walk away for a while and do some thing else. Sometimes you can have things that seam really stupid cause big issue . I had a mold that I just made when I used it the parts looked horrible the parts looked like they were melted but the mold looked awsome. It turned out that I forgot to put vent holes in the mold and it sealed top and bottom so well as it cooled down It imploded the mold and crushed the parts I saw I had no vents and no other ideas so I added the vent holes repoured The part and wow problem cured . And I have made a lot of molds but never had a problem like this . There is always something new. Well that's it for now thanks .

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rocky...thanks for the lesson.........superstock

[Excrewchief]

As always keep them coming.

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is a vacuum chamber an pressure pot both needed for casting?? or will a pressure pot by its self?? superstock

[Excrewchief]

If i was to choose one or the other and could only have one i would have the vacuum.
That is where your mold quality comes from . So your going to get a better product.

I have taken a good mold mixed up resin poured it in then take a dremel tool and help it up to the mold and got enough vibration were you can sit and watch the bubbles come to the top . And ended up with very nice looking parts.. if you look around you can find the pressure pots at goodwill the last two that i got cost me 6.99 each.
The vacuum pot that i like best is a pressure pot that has a hole cut in it and some plexiglass siliconed in so you can watch it to keep it from bubbling over and waisting silicone. Just the other day i went to a store that buys estate sales all the furniture and he told me that he has about four in his storage that he is going to go get them for me. He said he gets them all the time.so there out there very cheep you just have to look for them. It is well worth the money . If you know any a/c guys you can get a used vac pump real cheep if not free.as they get old they blow an oil vapor so they will by a new one but the old one is still good just wrap a rag. Or towel around the vent so it doent make a mess. And watch the oil level. They dont use much a few oz a month. If your mechanically handy you can also make a vac pump and pressure pump from an old a/c compressor of a car . Hooked to an elec motor. So there are a bunch of ways to do it very cheep. Good luck and have fun with it. Rocky

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rocky..show me a picture of your vacuum chamber..superstock