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Thread: My New Pressure Chamber

  1. #1
    Join Date
    Dec 2009
    Mount Sterling, KY

    My New Pressure Chamber


    I cast pen barrels on occasion and have always done the onesy towsy thing but I wanted the ability to cast multiple barrels on a 10 inch length of tubing in one shot so I made a long round mold out of 5/8ID PVC tubing. However the overall length of the mold did not allow use of my 2gal paint pot I normally use as a pressure pot for my castings. Needed something longer then the paint pot turned on its side. Three inch PVC to the rescue.

    The mold. Its about 13 to 14 inches long, in any case much longer then the depth of the paint pot. More on it in another post.

    A comparison of the new one to the paint pot.

    How it is mounted, the pressure end and the access end with the mold inside.

    I used a 3" clean-out adapter for the access end but could not get it to seal. Had two of the threaded plugs so used a section off the bottom of one and glued into the bottom of the thread female section to act as a seat for a gasket. The first pic shows the plug with the psa foam I used as a gasket. The second pic shows the trimmed down plug being used with PSA sand paper to sand the seat smooth.

    Installation of the seat. I took a saw kerf section out of the seat section so that it would collapse a little and go far enough down into the female fitting to allow the plug to use all of it's threads when screwed in. Glued the saw kerf together and filled the back side of the seat with PVC glue to seal it and keep it in place.

    The only negative to the assemble is that the clean-out is the only part that is not schedule 40 and is not intended for pressure use. However, it does have almost 1/8" deep threads and is nearly 1/4" thick through it's cross section. Although schedule 40 is rated at around 160psi I am running at most 70psi. I tested it to 80psi and noted no creaks or groans so I am not worried about it not holding up. It still leaks a little, drops from 60psi to 40 in about 30 minutes but with a compressor attached overnight that is not a problem.

    Appreciate all comments.
    Last edited by James Combs; 01-04-2017 at 8:17 PM.
    JD at J&J WoodSmithing
    Owingsville, Kentucky

    "The best things in life are not things."

  2. #2
    I think it all looks interesting, but I don't know what a pen "barrel" is or why it needs pressure.

  3. #3
    If it's schedule 40 pipe (about 3/16" wall thickness for 3" pipe), the rated burst pressure is over 500psi, so you've got a lot of margin. You might blow the ends off well before that though, depending on the quality of your weld, so I'd stand to the side, not the front. ;-)
    Last edited by Steve Demuth; 01-27-2017 at 9:53 PM.

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