This is what I have done so far in the pewter medallion project.

The initial test castings are actually in a mystery metal lead/antimony alloy, and thats probably why I am having casting issues....

These will be cast eventually in 100% lead free pewter, which almost certainly will have different casting properties than what I am using now...
(Mystery salvage ingots from a local gun shop, mixed with salvaged weird alloy from 1960s era British .303 ammunition that I broke down for components after nearly 90% of them proved to be duds that would not fire.)

I say weird alloy because when it came out of the copper jackets, it was a strange, bright brittle, silver color that melted oddly.

I got the ammo out of a sealed armory "tuna can" originally, and it was marked ball- so its not magnesium or something equally ghastly.
I believe its a really high antimony alloy that might have been mixed with tin for economy.
As it was 1960s stuff, it would have been home defense emergency stockpile, and anything is possible at that point.

However, I won't be using it for the final casts, so it doesn't matter.

You can see from the photo that the metal is cooling too fast as it goes into the moulds.
The ripple effect is due to that; along with the ragged edges where the metal did not fully fill the cavity before turning too solid to flow.

The far right cast is the best so far- mould almost too hot, and the rough looking "frosted" surface is from the overheated mould.
The center one came from a badly overheated mould cast- the frosted effect gives a very rough and unpleasant surface.
The left one is from a "cold" mould- nice, shiny and smooth surfaces- but incomplete fill, and rippled as the metal cooled in waves that would mean the medallion might actually fracture along those lines some day if I leave it as is.
The sprue is also still on the left one. its been cut from the others.

I'm going to see if I can get some pewter alloy in a couple of weeks and try again.

As for the design.
I made it by grinding and polishing some tool steel punches and sort of forcibly "smooshing" the aluminum around to make a sunken design in the metal for the pewter to flow into.

Not bad for a first try, actually.
I may go to either thick brass bars for the heat control, or just break down and buy soapstone to carve a design into for its excellent insulating qualities.
The thin aluminum is cooling so fast, it just may not be suitable in the long run.
But it was worth making just for a proof of concept, even if I have to scrap this one and start over.


-Badger-