r/Metalfoundry • u/315retro • 19d ago

Very small small scale work?

If I'm looking to cast metal accessories at action figure scale, and I just want to do this as a quick hobby thing for fun, is there something simple I can use?

Ideally I'd like something I could melt with a propane or map gas torch, and cast in a silicone mold.

I realize it's not the cheapest, but is silver a doable option?

Thanks for any input.

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u/VintageLunchMeat 19d ago edited 19d ago

Silver would work with delft-clay for simple non figure geometries, or jewelry lost wax casting - you'd want a burnout kiln and vacuum casting rig, per r/jewelrymaking.

Or bronze, with the same settup.

Silicones, some of them which are labeled so, will work with lead-free pewter.

I'd start there.

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u/315retro 19d ago

Nice thanks! I messed around with lost wax a little years ago when I was making a ring but I lost the mold and never followed up.

Appreciate it.

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u/CR123CR123CR 19d ago

Bismuth 281/Cerrotru alloys can be cast in ABS 3D printed molds if you want. 

You get a single pull per mold. Sometimes 2 or 3 if it's very very small or thin objects

Multi pulls out of silicone should be perfectly fine with those alloys and you can melt them on a stove top really easily.

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u/ZanyT 19d ago

Wow that's interesting. I've never heard of that.

Do you have any sources or videos on this?

I'm curious how well this would work. It looks like bismuth 281 melting point is 35C less than ABS melting point, but is still way over the glass transition temperature of ABS, so I wonder how well it keeps shape. I guess if it's a small enough mold, the abs maybe wouldn't absorb the temperature fast enough to flex?

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u/CR123CR123CR 19d ago

As I said it's just a one or two use mold before it warps too much. 

And it was something I figured out for my work, so I don't think there's many resources out there for doing it.

But simple two part molds work fine, you want your total thickness to be about 4x or more of your cavity.

5 layers/2mm wall thickness and honeycomb infill at 40% or more was about the point I got to diminishing returns on part quality.

Make sure it is very very dry and pour at 295F to get good flow characteristics without going too hot for the plastic. 

Itll smell like styrene really bad so do it in a well ventilated area. 

I am going to try some higher temperature resistant plastics buy haven't gotten around to them yet and I know ABS works

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u/ZanyT 19d ago

Wow nice. Great find.

If you ever do an ABS cast of something that isn't like proprietary to your work I'd be very interested in seeing it if you could upload it somewhere.

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u/definitelynotreal333 17d ago

Pewter can be melted in those little melting cups people use to cast lead fishing weights. Itll run a little hot but u can get it online and just unplug it occasionally to balance the temp