Casting Copper

[gwrdriver]

I have a need for a rather delicate machined copper ring but to make it from solid stock I must use a disc 2.75" diam x 1" (pipe won't do it) . . cost maybe $30. I have a bunch of clean/new copper scrap and can make a pattern, wax or wood, so what problems am I likley to encounter melting copper scrap to pour such a ring? I have an idea that all things considered this isn't worth the trouble for what's involved but I thought I'd ask.

[alphawolf45]

This is the sort of thing I wouldnt even worry about, just do it..Certainly some of the sharp fellows can tell you why its bad idea but I aint so sophisticated I just get it done........Were it not for being able to cast metals I'd be up a creek as I cant afford to mill and turn from large commercially produced solids ..

[Bellien]

OXYGEN! It's a bastard.

Make sure you degas, it's AMAZING how fast copper can soak oxygen out of the air.

This article has some helpful advice, does it have to be copper? what about a bronze? pouring silicon bronze is almost dreamy compared to pouring copper.

http://www.keytometals.com/Article64.htm


Edit: Added link to article, I forgot to when I originally posted.

[gwrdriver]

does it have to be copper?

Yes

[hammermill]

keys to metals gives the following notes on copper

Pure Copper and Chromium Copper. Commercially pure copper and high copper alloys are very difficult to melt and are very susceptible to gassing. In the case of chromium copper, oxidation loss of chromium during melting is a problem. Copper and chromium copper should be melted under a floating flux cover to prevent both oxidation and the pickup of hydrogen from moisture in the atmosphere. In the case of copper, crushed graphite should cover the melt. With chromium copper, the cover should be a proprietary flux made for this alloy. When the molten metal reaches 1260oC, either calcium boride or lithium should be plunged into the molten bath to deoxidize the melt. The metal should then be poured without removing the floating cover.

i know the bigger and purer the copper you can find the better(scrap yards prefer brite) stuff that has been burnt has greatly diminished recovery. some not worth the time

beyond that go for it

[Fender]

Can't speak to the chemistry, but having melted copper scrap to make bronze, the melting temperature is similar to cast iron (~2000ºF). Bronze is lower (~1600ºF). Would it be possible to form this to rough shape from a copper strip 1"w X 9"L, and silver solder or weld the joint? I know Marty Knox has done TIG welding on copper.