Building a vacuum assisted caster for silver and gold.

They only last for a limited time. When they lose their ability to seal, you replace them.

I have a friends vacuum caster living in my studio, so I don't need to make one. But I, too, gave this some thought years back.

There are two approaches that made sense to me: One was to use a $15 air vacuum pump from Harbor Freight with a compressor and build a box out of plywood with hoses; the other to use a electric vacuum pump. What I found out recently was that the Gomco vacuums that get sold all over Ebay for relatively little money pull the right amount of atmosphere to do jewelry casting/investment work.

I found this out because I got a Gomco in a lot of dental supplies that I bought last year, and was researching them. For some reason, they cost a lot less than many other comparable vacuum pumps.

When I was looking into this years ago, I didn't have the money for a vacuum or compressor, so it was really lucky for me that my friend needed to find a home for his caster. I use it primarily to vacuum investment and on castings using more than 5 ounces of metal. I prefer the centrifigal caster to the vacuum; just think it gives you denser castings.

Why are you making airtight cans for your flasks? I primarily set my flask on top of the silicone ring over the intake hole and pour away. The vacuum pulls through the investment.

Debbie K