Making Hollow Forms With Non-Conforming Dies

This term at jewellery night class we are learning about hollow forms, boxes and hinges. I'd prefer to try hinges at home myself where I can see better so I decided to try making hollow forms using a non-conforming die.
 A die is a tool that is used to shape metal. A non-comforming die consists of one part as opposed to a conforming die that consists of two parts such as a dapping punch and dapping block where the metal fits between the two and is formed into a domed/concave shape.

The die I made is called a silhouette die and consists of a shape cut out of the middle of a non-compressible material such as wood or acrylic. I cut this out using a jigsaw then filed it to smooth the shape a little. The hollow form will be formed by pushing the metal into the cutout.

The college doesn't have an hydraulic press so we were going to form the metal by hand using dapping punches which meant the next step was to make marks for the screws which would hold the metal in place.

After annealing a piece of 26g gauge copper that I'd added a spiral texture to using my Bigshot (pre rolling mill) I screwed it into place over the die with the screws just catching the edges rather than going though the metal. As you can see from the holes I overdid the number of screws a bit. I thought there would be a lot of pull on the metal as I formed it but surprisingly there wasn't.

I used dapping punches and a mallet to push the metal into the oval-shaped hole I cut out, removing once and annealing it in the middle of the process (all those screws!) I carried on forming it and ended up with quite a deep impression. The spiral texture was stretched a bit and was less obvious but it was still there.

The next step would be to flip the die over and do it all again with another piece of metal to create the mirror image back part of the hollow form. That was the plan until I noticed there was a split in the metal near the top! I'd gone just that bit too far with it and being very thin metal it gave way.

It was a shame but it was my first attempt and that is how you learn. Practice make perfect as they say! I have the die and screws at home so I'm going to repeat the process with some 22g copper and not take it as far this time.

The plan once I've formed the two halves is to trim around the outside of the shape on one half which will then sit inside the other half for soldering the two parts together. Then the excess metal is trimmed, filed and sanded to produce a neat solder line. A hole needs to be drilled somewhere to allow the hot air to escape from the middle of the hollow form during soldering to avoid it exploding. This could be holes for threading a chain through or maybe part of the design.

Hopefully if it all goes to plan this time I'll be posting my finished hollow form piece (without any splits) soon :D