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Cast Bronze Fittings?

Kumdo

Kumdo

Joined
Mar 7, 2000
Messages
1,048
I'm about to start carving for lost wax fittings for a bowie that I'm working on. Has anyone done this? It occurs to me that there might be shrinkage in the bronze, so a perfectly fitted wax guard might end up being too small. This isn't a big deal for the slot because I can re-fit it with files, but since this is an S-shaped guard, I'm afraid the curved to and bottom elements may not sit square on the "shoulders". Is there a way to cast it so that it doesn't shrink? I won't be doing the casting myself, but hope to use a local sculpture artist for that. Any input or tips are very appreciated...

Thanks!
 
Shrinking is part of the solidification and cooling process so it's always there . What you have to do is make the wax oversize to compensate .Someone should be able to give you some numbers to work with.
 
mete said:
Shrinking is part of the solidification and cooling process so it's always there . What you have to do is make the wax oversize to compensate .Someone should be able to give you some numbers to work with.
Click to expand...

Since bronze composition probably varies a lot I wonder if there is a dependable shrinkage gauge, keeping in mind the tight tolerances for the slot. Even so, if I had a close idea, I could factor in the top and bottom curves and just file the slot to fit. Thanks for the input!

BTW, I just saw this:
http://en.wikipedia.org/wiki/Riser_(casting)

Am I reading it wrong or does it sound like you can eliminate the shrinkage by using this method?
 
Risers do not eliminate shrinkage,they lessen it in areas of different thickness of the finished piece.they help prevent shrinkage tearing due to the time thicker and thinner portions of the piece during cooling. if you are having it cast ,live with the 3-5% shrinkage and file to fit. you will be getting a rough casting from the foundry ,the word "rough" says it all. it will need filing and sanding before mounting.
 
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