One of my students came to me with a problem. He is designing his capstone project which will involve a robotic controlled device that will punch out 5/8" thin metal "coins". I think he is planning on using pop can aluminum. He wants to know how to make a male/female die to accomplish this. I'm thinking some 5/8" steel rod hollowed/sharpened out for the male part and a block of metal or wood for the female die,backer. I'm no machinist so it was "Quick Batman; to the HAMB!" Any other, better, ideas? Thanks.
Easier said than done.... Commercial punches are available, but I'm assuming the student wants a flat disc. The commercial punch designs won't do that, all will deform the disc to some degree or another. And it's actually easier to build a punch to cut thicker metal (although the force needed goes up sharply) rather than thin material. To cut thin material, your die set needs to be very close tolerances; the OD of the male die needs to be no smaller than the ID of the female die plus no more than 1/3 of the thickness of the metal to be cut. Keeping the two dies aligned is a major issue also; you need a very rigid fixture to hold the dies. And soda can aluminum is really soft; the main body of the can is made from a 4" diameter blank, with the outer 1/2" being 'drawn' into the sides. They use the same blank for both 12oz and 16oz cans, it's simply 'stretched' more for the bigger can.
After thinking about it some more, take a look at paper punches. You may be able to scale that design up and get a functioning punch. Be aware that as size goes up, the amount of force needed goes up exponentially.
A leather punch will cut beer cans and flashing with a sharp blow from a hammer. I've not seen 5/8 but I'm sure there is.
I'm interested in this myself. The reproduction brass "Trash Can" condensers I am making should have a brass strip connecting them to the distributor post instead of a wire. The original straps that came with the original Mallory distributors we made of .040 brass. They were shaped like a "dumbell" with a hole for a #10 stud in each end, about 1 1/4" long. I have looked into having these made commercially, but to get a decent price, I'd be buried in the things, and to get a reasonable quantity, I'd go broke. If someone can figure this out, I'm in.
A grade 8 bolt and nut. Weld the nut to a steel plate. Drill a 5/8 hole through the nut and plate. Then drill an 11/16 hole from the plate side to halfway through the nut to make it easier for the pieces to fall through. Use a bolt that has a section of smooth shank. Tap a hole in a steel plate. Screw the bolt into it and cut off the head. Slide the bolt into the nut and make some type of mechanism to keep it aligned. Either a hinge so it works like a stapler or a triangle arrangement of 3 pins in holes.
Maybe this would work. The instructions say to sharpen it by punching thin aluminum. https://www.createforless.com/Uchida-Clever-Lever-Craft-Punch-5/8-in.-Circle/pid82609.aspx#ViewRate It's also available on Amazon. Under $6.
Thanks for all the replies. I'll pass along the suggestions. He wants to mechanize the processs acts another story. Paper punch may well do it and the idea with the grade 8 bolt, nut, and plate is interesting.
I have used something like this to provide 18ga cold rolled steel sheet knock outs to fill holes. Granted I have to use it with an arbor press and breaker bar... but it cuts well and doesn't deform the blanks. No need to recreate the wheel so to speak. Best of luck. Jeff
The Jalopy Journal
