Polish ring making

Many years ago a friend of mine told me about a group of Poles he used to know, who lived in West London, who made gold rings by melting the gold,
pouring the molten metal into a mould and whirling it round on a piece of string. I suppose it's a low-tech form of centrifugal casting. Has anyone else heard of this technique?
Leon
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Leon Heller, G1HSM
http://www.geocities.com/leon_heller
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It's called Sling Casting. I've done it with pewter. Worked pretty well. The sprues have to be small enough that surface tension prevents the molten metal from entering the mold by gravity alone. No larger than 14 gauge B&S, you'd probably need more than one, I used 2 sprues to cast single rings, 3" swords and battleaxes. Maximum flask size is suggested to be about 3"x3" from the book: Practical Casting by Tim McCreight. I also like his book: The Complete Metalsmith. Karl

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Leon Heller wrote:

My dad, to whom I owe undying gratitude for pointing my eyes towards technology, was born in Lodz, Poland. He learned jewelry making in pre-nazi Germany, came to the US in 1921, and remained a jeweler all his working life.
He told me about sling casting, though I never saw him use it. His shop had a couple of hand wound spring driven centrifugal casting machines mounted down inside galvanized iron washtubs, to catch any splatters.
The mainstream production method there was lost wax casting. As a kid, I got pressed into making thousands of "waxes" of rings, bracelet links and other doo dads. These were made using reusable rubber molds. We had a smaller centrifugal machine for for making the waxes back then, pressure injection of molten wax hadn't achieved popularity yet.
We also had a few multipiece metal molds used for making waxes. These predated the rubber molds. They were made from a low melting point alloy by craftsmen who encased a sprued "master" with modeling clay and then carved away a section of clay and replaced it with poured in melted alloy. They repeated the process until all the clay was replaced, and through that process they created a multipiece reusable alloy mold. Ordinary nail polish was used as a barrier to keep each successively poured alloy section from fusing to the earlier ones.
Dad also told me about a technique he'd seen used in europe which involved jamming several layers of wet cloth over the molten metal to create steam pressure to help push the molten metal into a mold.
Thanks for the mammaries,
Jeff
P.S. For those who might be able to use this information, there's a web site containing Ellis Island immigration records:
http://www.ellisisland.org /
I stumbled onto it a couple of years ago and was able to locate and download the image of one page from the passenger manifest of the ship which brought my dad and his family to America in 1921; and a photo of the ship itself. They are framed and hanging on our kitchen wall. It's nice to glance at it from time to time and reread the names of the family members I knew as a child, all listed together line by line on that manifest, and all categorized as "steerage" passengers.
JW
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Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"My luck is so bad that if I bought a cemetery, people would stop dying."
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