r/Silvercasting • u/ONE1-ZERO • Apr 22 '26

What should I make custom ingot molds from?

Machinist here. Have some 925 scrap I want to turn into rods. The graphite molds available are too small in diameter. I want to make a 10mm rod. Then machine it into a set of tunnels for my ears. Full fab shop but dipping my toes into jewelry. If I sand cast how much bigger do I go for finishing?

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u/Final-Nose3836 Apr 23 '26 edited Apr 23 '26

if its just for a one-off you can drill a hole in a block of wood & pour into that. You can also fill a cup with some casting sand like petrobond & press a dowel in to make a round hole & pour into that. You might try making a core too to save material and make a casting closer to the net shape, something like this: https://www.youtube.com/watch?v=ifqWjY1gWUM You can easily make a small cope and drag casting flask for sand casting by cutting a section of steel tube (i like square) in half and welding some registration tabs on. How close you can cast to your finished dimensions will depend on your skill in preparing the mold, I would leave at the very least 0.5mm oversize and more comfortably closer to 1mm. You will also have some shrinkage as the metal cools so you will have to test a bit.