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Tuesday, March 6, 2012

Full Metal Cabochon From Sketch To Cab

I was watching a motorcycle show and became aware of the rivets they were using on a choppers gas tank. I began sketching and came up with this idea. I had just dapped a disk of copper into a low dome and that was to be the base. I had scraps of bronze and aluminum and dapped two more disks.

Making disks is easy you just anneal the metal and use a large punch to force the disk into the curve in the block. Then we have to cut apart the disk to get the shapes to surround the the rivets.

 Trial fit each piece to the base.
Keep cutting and adding

When you get all the parts cut out its time to cleanup the metal. I pickled the metal in sparex, an acid prep that removes the fire scale.

I marked the location of the holes with a sharpie and using a punch made 1/16 inch holes.

Since punches deform the metal I returned to the dapping block and rounded the cup again, then set the rivets.

It was about this point I realised I had reversed the colors from my sketch . I punched the holes and riveted on the points loosely. Then back to the dapping block to finish the rivets and conform the plates to the base.

The finished product is about 7/8 of an inch across. I had considered it to be a ring but after finishing the construction and texturing it seems more like a cabochon.