3D printed hammer form

[Steve Broady]

I just tried an experiment, and since it worked out pretty well I thought I’d share with folks here.

The goal is to make some copper slant plates for a Boka style LM, but they need to fit into a stainless steel tee and be soldered in place. You can see the cross section here:

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In order to make them, I decided to try 3D printing a form which I cold hammer some copper over. The yellow trapezoid in the drawing is that form. It’s also the reason why I took the time to draw this part accurately in CAD.

I printed it in PETG, using a heavier than usual wall thickness more solid infill. The result was a nice solid feeling plastic puck.

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I cut two pieces of 1” copper pipe, annealed them, then split and flattened them out and cut them to shape.

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I just used a clamp to clamp the whole thing to the workbench and started hammering the edge over.

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I had to re-anneal them half way through, but they came out pretty well after just a few minutes of work with a ball peen hammer.

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The 3D printed form worked perfectly. It wouldn’t stand up to making hundreds of parts, but for one or two it seems like a great way to do the job. A top form would be helpful, but for this I felt it was simple enough that I didn’t need to bother.