Dies for forming copper sheet

I'll start by saying that I am CHEAP. That and I like to make things. So when I upgraded my computer I skipped buying a CPU heatsink and made some water blocks out of copper until I got one I liked. I use it and a Harbor Freight fountain pump ( HF 41198 ). It seems to work well in that the temp reported by the Bios is 110 degrees F. Max for a Athlon xp2400. The pump just sits in a stainless tank with maybe three quarts of water.
Anyway the last water block I made using a recess in some oak that I milled with a ball end mill. And I used a ball pein hammer to form one piece of copper. After making that part I brazed it onto a thicker piece of copper and brazed in a couple of copper tubes for the tygon tubing to fit on. I used SIL-FOS WITH 15% silver ( BCuP-5 ) and a hand held propane torch to do the brazing. I annealed the copper about three times while doing the forming.
The recess in the oak is 40mm by 55 mm by 11 mm deep. Now my question is if I were going to use two dies to form the copper, what would the first die be? My thoughts are something like 20 mm by 30 mm and maybe 8 mm deep. I am thinking this would stretch the copper more in the middle. But I don't have any books with info on forming using dies and the local library is not likely to be much help.
Dan

Try http://www.bonnydoonengineering.com/ceilidh/ceilidh.html
Les
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Thanks!!! It will take me a long time to absorb all the information there, but I will know a lot when I do. Exactly what I need.
Dan
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I would stay with the 40mmx55mm die & make the punch 4x material thickness smaller if you think that you can live with a little angle around the perimeter. Make the punch a full 11mm deep & experiment with different thickness of copper & depth of first hit. Chances are it can be done in 1 hit with the proper clearance & annealed copper of the right thickness.The die will need to be built with a rectangular clamping ring around the skeleton perimeter so as to prevent distortion.The punch will need radii on the leading edges to prevent perforation. Experiment with lesser depth of hit in between annealing processes if It cant be done in 1 shot. good luck

Thanks. As I said, I used a ball pein hammer to get one. But now I want to try doing it using a punch as well as the die. I can easily live with an angle, but did not know any " rules of thumb " to use on my first attempt. The copper I want to use is .025 inch thick. Roof flashing from the scrap yard. The die has a radius on it from the ball end mill I used to make it, so the punch will have at least that much radius. I used oak for the die as it was just a basement experiment, but can go to steel. Thanks again. Now back to playing in the basement.
Dan
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