Hi all – I'm suddenly fascinated by lathes, coining presses, and other machine tools. I feel like I completely missed out on a major technological domain. Have any of you produced your own medallions or coin replicas? How do you achieve the "upsetting" of the discs? Is this something where you need a bona fide upsetting mill/machine, or can you just leverage general shop tools? It seems like upsetting mills for coins were a big deal when they were introduced in the 1800s, but the basic operation seems basic enough that other machines should be able to manage it. When I search for upsetting machines, I get results like these but I don't understand what I'm looking at. They're not the coining kind, and they're huge. I want to make some 1-inch and 2-inch medals, and vary the depth of the field / the rise of the upset rim. Thanks.
I've never done what you're proposing. I don't see using traditional machine tools for the upsetting function. It would be extremely awkward to make them try to do something they weren't meant to do. But, do you own any machine tools like a metal lathe, horizontal or vertical mill, shaper? If you do, then I presume you understand the concept of "making tools from tools". The upsetting tool is a pretty easy and simple machine to make especially if you aren't looking to provide edge ornamentation. The artistic engraving would be beyond me. The basic upsetting tool is two not-quite parallel bars, one of which is fixed and the other movable horizontally in relation to the fixed bar. If I was making one, I would mill a groove in both bars that was the thickness of the intended upset rim. It would be tapered end-to-end. Movement is effected by a hand-cranked gear engaged with a rack on the movable bar. Adequate baseplate, anchoring and fixed guides for the movable bar are obvious needs. Length of movement must be designed for more than the circumference of the intended blank. A little force analysis to determine sizes, reactions, gear ratios, etc. and Bob's your uncle.
