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'diy' pressure pot

Discussion in 'Molding and Casting' started by kinetic, Apr 17, 2011.

  1. kinetic

    kinetic New Member

    I've been searching around and it seems like a lot of people use pressure paint tanks from Harbor Freight as pressure pots for casting. Thing is, they always say they use the pot with "a bit of modification" but I've been searching and searching and I can't find out what that modification is exactly.

    If anyone can let me know what extra parts I need to buy and what I need to do to the pot I'd really appreciate it :)
  2. If I get a chance I'll take a picture of mine. It's pretty simple you just need fittings to make it fit your line or system that you use. I can't remember exactly what I did so I'll take a pic when I get back over to the shop.

  3. I removed the internal tube in the lid. Put a cap on the fitting for the output of the tank. Then put a on/off butterfly valve on the input so you can shut the air off and keep the pressure in the tank. I think you will find the cheap pots have a very cheap regulator on them. The regulator is made of pot metal and will crack if you torque too hard on the fittings. With that in mind, I removed the regulator. So, I have a quick connect for the air line going into the on/off valve (butterfly) into a Tee fitting that has a pressure gauge on one leg. Then a strait pipe into the top of the tank.

    When I pressurize the tank, I just use the gauge to see the pressure and then close the valve when the pressure gets to 50-55psi. The pots have a blow off on the output side that will start bleeding the pressure at around 60psi.

    I can get pictures too.
  4. kinetic

    kinetic New Member

    thank you both! I bought the tank yesterday and by looking at it and your descriptions I think I can make it work.

    I'm so excited to cast my replica skulls without having to manually poke bubbles out of each tooth ;)
  5. ljones

    ljones 1994 wasco award winner

    i woud like to see the pictures , you guys said you would post, thanks
  6. About as simple as you can get.

    Attached Files:

  7. Vince, the only thing I notice about your setup is that you eliminate the ability to use the stock regulator with the way you have the in-feed air piped in. If you moved you air in pipe, with the shut off valve, over to the infeed on the regulator, you can then use the regulator to adjust the air pressure in the tank. That will allow you to leave the tank connected to your air supply overnight and hold the same pressure on the inside of the tank. I know I sometimes get a small air leak that drops the pressure over night.
    I have a pressure tank with that set up at TFB and it works great to hold the pressure right where I want it.
  8. I have a regulator on the compressor that I make that adjustment with....is that the same thing you are talking about. I never leave stuff in that long. I mainly use 300 and 325 so it sets pretty quick. What are you using that requires it to be under pressure for so long?
  9. kinetic

    kinetic New Member

    It's been a while but I thought I would post mine too.


    I had no prior knowledge of pipe fittings so the first trip to Home Depot was a bit confusing, but I figured it out and the tank works great. For $100, I should have gotten one a lot sooner. It only leaks from 60 to 50 psi over 12 hours, which is fine for the clear casting epoxies I use that need a longer cure time than urethanes.

    My stock pot vacuum chamber is on the right :)
  10. Remember, if you can fit the mold in there, you can also "Pressure Mold" by pouring your mold and the putting it in the pot to cure. Just don't unload the pressure before the cure time on the rubber. Major air will appear.

    Cool set up.
  11. kinetic

    kinetic New Member

    thanks :)

    that doesn't work for making molds of hollow things, does it?