Thanks George.
I am accustomed to melting cast iron in this furnace and have experienced the increased heat of the melt with that material. I certainly will gain as much knowledge as possible before attempting anything... if it is deemed entirely untenable, Ill not attempt it all. Anyone out there have any direct experience with this???

Thanks for your comments. To clarify: the recycled metal forming the art casting need not adhere to the exacting performance testing such as those spec'd in ASTM and other such testing organizations. My concern is primarily aesthetic. Im quite certain that the metal composition and therefore its properties will be altered. These will likely complicate working with it. As long as I can fabricate with it (weld/ machine and finish) in a manner pleasing to me- I would consider it satisfactory- warts and all. At any rate the allure of even a modicum of success makes it worth trying. I built a cupolette-style furnace (w/ lid). This design is more of a batch melter than a continuous one which recoups more heat than a cupola. If run carefully the melt zone tends to oxidize less than a standard continuous melter.
Im wondering if you are able to expand on your comment regarding a controlled atmosphere??
Additionally, I am aware of the hazard posed by the melt's high heat and chromium content.

Regarding the controlled atmosphere:

When melting any ferrous metal, (and most non-ferrous), it is common in industry to perform the melt in a controlled atmosphere. Generally, an inert gas such as argon, helium, nitrogen or carbon dioxide is maintained in the induction furnace to prevent oxidation, absorption of undesirable elements or other variables during the melt. High carbon steel is particularly prone to losing carbon through oxidation, most steels are better without excess sulfur, etc.

In a cupola-type melt, the metal is essentially subjected to open flame and thus highly prone to oxidation if the atmosphere is not maintained in a reducing state by the addition of some material to consume free oxygen. Stainless steel, generally composed of iron, nickel and chromium, is only stainless if the chromium carbides are in suspension and the surface chromium is oxidized. If tramp elements are introduced, these balances can change. Thus the use of controlled atmospheres. The need for atmosphere control necessitates isolating the melt from the flame and free atmosphere, so induction furnaces are appropriate, or muffle-type furnaces or closed crucibles.

I'm not too knowledgeable about cupola melting, so I can't say how you could control the atmosphere in one effectively. Building a cupola that will withstand for a sufficient period of time the more than 2600F temps necessary to melt stainless may be a problem, too.

Finally, your desire fora michineable final product concern me. Typically, steel is cast into ingots large enough to be rolled down to billets and then into finished form aftera reduction in section of some 85% or thereabouts. This high degree of reduction is necessary to develp the tight grain structure necessary to have a piece that is both strong and dense enough for machining.

I wish you luck with your efforts and look forward to hearing how it comes out.

I just stumbled across this site. As a metallurgist in industrial investment casting foundry, I have a couple of thoughts. Temperatures for castings should be around 2800F for good flow. the thinner a section, the more heat you need to keep it from freezing off too soon. Also, stainless steel is a mushy freezer, more prone to shrinkage porosity than bronze. (I haven't worked with Al).

I don't think grain size will be a factor for machining castings. SS is gummy, so tends to wear cutters faster.

I agree that induction melting is better than cupola. I don't know much about cupolas: doesn't it work by burning carbon, so are mainly used for cast iron? If so, then that it going to change the composition of your SS if it is in direct contact with the carbon. 316 stainless is supposed to be low carbon. Some bad things can happen to 316, as far as carbides in the grain boundaries, and how it can react to heat treating.

No matter how much you shield, you will not be able to overcome h20 and excess oxygen in a combustion system. In induction heating, you can shield by a liquid nitrogen drip, or flowing gaseous Nitrogen over the melt, and keeping a lid on it as much as possible. You need to make sure you have good ventilation.