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New to Vacuum Casting?

I’ve been wanting to get into vacuum casting so I started by putting together a investment chamber. I used a thick steel pot, 3/4" acrylic and pretty much followed a Youtube video or 2. I’ve tested it and it holds pressure fine. When I posted it to a newbie jewelry group I had someone tell me my set up is “extremely dangerous”. I’m inclined to build what I can and enjoy doing so but maybe I don’t know what I don’t know on this. Any advice appreciated. (The stuff on the acrylic is CA glue residue as I had glued a gasket and then removed it).

I can’t see anything specific that is dangerous here.
Maybe I have the same problem as you?


I, too, don’t see anything harmful in your setup. I’ve been using a very large (30" across at the base) 1/2 thick acrylic bell jar for 40+ years and it’s still going fine. You might find you’ll want a thin gasket between the lid and the pot…thin so it pulls tight and isn’t sucked into the pot. A thick gasket, in your setup, might have a tendency to be pulled in…depends on it’s durometer. I assume the pot you adapted has fairly thick walls and is stainless.

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Thanks for the feedback. Yeah, the pot is 8" thick and rigid stainless steel. I checked under pressure to see if there was any bowing on the pot or the acrylic and both were fine.
Yeah, Frank on the gasket I was kind of thinking that after I had glued (bad idea) to my lid so I took if off. It left glue residue so I flipped it over and tried it without a gasket and it held pressure. Funny thing, the gasket I had, before I glue it, was thin and worked. It was cut from a silicone cat may my neighbor gave me she had got from a dollar store.
Thanks again, I really appreciate the feedback.

I suspect the person who said it was dangerous thought it was a pressure pot rather than a vacuum pot. The worst that could happen with your setup is that the lid or pot would crack ruining your flask.

Even as a pressure system it would be harmless.
Max pressure will be the weight of the lid.
Which will be way less than any component can handle.
There is no mechanism to lock the lid.

Regards Per-Ove

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