Gallery, Projects and General > The Design Shop

Expanded coin making

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Sid_Vicious:
What about an expanding mandrel? Think like an lathe chuck with inside jaws expanding out and stretching the outer ring.

efrench:
They use a mandrel and a hide mallet. 

raynerd:

--- Quote from: efrench on February 26, 2016, 02:06:49 PM ---They use a mandrel and a hide mallet.

--- End quote ---
But there isn't a central hole to hammer it onto.
--- Quote from: Sid_Vicious on February 26, 2016, 11:36:17 AM ---What about an expanding mandrel? Think like an lathe chuck with inside jaws expanding out and stretching the outer ring.

--- End quote ---
Yes,I can imagine that but foresee it splitting the edges.

efrench:
How about a set of short mandrels? 
Does the metal in the coin work harden or is it already hardened?

p.s. How about using a metal spinning technique on the lathe?

j1312v:
Hi,

I was thinking about your problem  :Doh: and I belive you need to make the cavity as close to the wall as you can, leaving a 0.02" wall thickness or less, then expand the coin with a mandrel  :hammer: by just a tiny bit say 0.005-0.010''.
What you want is to fit another coin in that cavity so just file the sides of the other coin so it fits in to the cavity.

You may get away from expanding the coin if the you can manage the leave a 0.015" wall thickness and then file/machine the other coin to fit.
I reckon per side 0.015 can't be noticed by eye. :borg:

Best,

Joe

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