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Building a vacuum assisted caster for silver and gold.

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Author Topic: Building a vacuum assisted caster for silver and gold.  (Read 1488 times)
Debbie K
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« on: January 20, 2016, 06:59:04 pm »

In hopes that this will save some of you having a vacuum casting failure I will share a piece of information that I didn't know about until a smarta$$ told me after I had problems.

In centrifigal casting, the spueing is done like a tree, with the feeder sprues coming off in an angle like a "Y" where the base of the Y is where the button would be.

When sprueing your wax for vacuum casting when you are placing the flask in a cavity, the feeder sprues should be horizontal, like a "T" to the main feeder sprue. This is because the vacuum does not exert the same amount of force ramming the metal into the investment and the metal has a chance to freeze before it can reach the bottom and go out to the sides.

Also, all vacuum cast flasks should have a minimum of 1' investment on the top. If you blow out the investment in a centrifigal caster, the metal generally will hit the back of the cradle and stop there. But with a vacuum caster, you can actually pull it into the caster. The man who "loaned" me his caster made this mistake and there's about 3-4 ounces of silver in the inside of the caster that's welded to the steel. If you sucked this into plastic tubing you could have a potential hazardous situation.

I know that your vacuum caster will work just fine and am looking forward to seeing pictures from all of you how you've made your own machines. But I would recommend that you give a thought to what would happen with the molten metal if you do have a blowout and where it is likely to go. The same thing can and should be said about centrifigal casters, which is why I bought a NeyCraft. The NeyCraft caster has a barrel that moves around with the crucible so if a blowout happens, the metal hits one spot on the barrel instead of being flung all the way around and bouncing around and out. And with casting, it seems, whatever can happen, does.

Debbie K
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