Thought it would be a good time for update on the jacket forming project. Just got back from heat treatment my disc blanking punch and dies. Since my last post I have made lots of design changes including new die bodies with threads that screw into a die plate. While doing this I also used the same footprint to make the disc punch and die. I chose in the end to use a 1 inch disc because I got good results with the prototype tooling. Die and punch was machined in 4140. The die was nitrided to about 58 rockwell C and the punch was through hardened and tempered to about 54 rockwell C.
The design of the die uses two symmetrically identical blocks that create a clamshell when mated. I used roll pins to secure the two halves. Each block has a milled step half the thickness of the copper strip. When joined, they form a slot for the strip.
The big difference to my prototype punch was the inclusion of a 1.5 degree shear angle on the face. This has had a huuuuuge reduction in the required force needed on the arbor press. Its now an easy 25lb of elbow grease (I'm using a 2' bar on the press). The end result looks pretty good. Just need to make an indexing stop to minimize the gap between each cutout on the strip.
More posts on the way. Just waiting on some parts from heat treating and should then be able to do a small run.