Investment casting question

Can anyone refer me to an online group devoted to investment casting?
Specifically, some guidelines regarding sprues and vents for very small
bronze castings using lost-wax models and gravity pours. Thanks, Dave
Anderson
Reply to
David Anderson
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rec.crafts.jewelry would be a good starting point.
Nice folks there.
Jeff
Reply to
Jeff Wisnia
You might also look at Anders Soderbergs's VIking Bronze site;
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Reply to
jk
[Gravity pouring doesn't work with very small amounts of bronze, or other metals like silver and gold. It tends to ball up and remain basically a spherical mass of metal due to surface tension. That's why people use centrifugal force or vacuum to force the metal into the mold when doing jewelry-scale castings.]
Andrew Werby
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Reply to
Andrew Werby
If you're well coordinated and gutsy you can put the flask, with molten metal in a tapered sprue opening, into a can with a bail and cord on it and whirl it overhead to create centrifugal force which pushes the metal into the mold.
I watched a jeweler do that once, but I never had the courage to try it myself.
At the opposite end of the temperature scale, around 1960 I watched a guy drink a small cup of LN without suffering any apparent damage, though he emitted the longest series of belches I've ever heard for about a minute afterwards. I wouldn't try that one either. (The guy was Dr. D.H. Tomboulian, a Cornell physicist.)
Jeff
Reply to
Jeff Wisnia
I suppose that it depends on the definition of "small" amounts. Even sub ounce quantities gravity pour quite well. Sub-Gram quantities might not. [Mixture of english and metric units intentional]
They will fill the small nooks and crannies of a mould better, and faster with additional force supplied by a cent caster or vacuum, or even pressure. We pour silver into ingot moulds for rolling out into strips to make coins from all the time. Works just fine.
Iv'e also had success with gravity pours of bronze melted in viking level technology [Open charcoal forge, dung tempered clay crucible, dung tempered clay "flask" around beeswax models, works just fine too. jk
Reply to
jk

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