Saturday, November 17, 2012

Low Tech Die Forming

The demo begins!

This week we had a Metalink demo at the ASU Metals Studio on Low Tech Die Forming. ASU's Visiting Professor, John Tzelepis, did the demo. This is a technique that combines the principle effects of the hydraulic press and chasing and repousse with neither a press nor pitch. It is a technique John learned from metalsmith Keith Lewis at a workshop. I did this technique as an undergrad but we worked a little differently and I think this version has some advantages. You need minimum 3/4 inch MDF and masonite, which you laminate together. You'll need a scroll saw or similar to cut out your designs. Keep the edge of the design at least an inch from the edge of the block.

Profile of a finished die with the formed example next to it

You will also need a sheet of 16-18g brass. Cut the brass to exactly match the edge of the MDF/ masonite design. The brass serves as a sharper edge to the wood and allows you to get a really crisp edge. If you do not use the brass and just have wood, your die-formed edge will never be sharp. Drill 4 holes approximately 1 in from the corners of the die on the diagonal. John uses the same size screws and drill bit for all his dies, about 3/8 inch. Any standard screw with sufficient length will work but make sure you use wingnuts to tighten rather than regular bolts. It's easier and faster to remove the screws.

Die with 18g copper plate screwed in and ready for forming

You also drill matching holes in your plate to be die-formed. In this case, John is demonstrating with 18g copper. In this photo he has set up the plate in the jaws of a pretty good sized vise, which is optimal. If you don't have one of these, you can clamp the piece to the side of a table, which is what he does for larger pieces that don't fit in even this size vise.

First course- creating the initial pillowed form

John is using a large dapping punch and just pounding into the hollow form underneath the center of his copper sheet. You can use a ball peen hammer but this is gentler and is less likely to warp or smash the brass plate underneath. You can also hammer with rounded wood or Delrin dowels if you like.

Truing the edge

 As you work the plate, the screws will hold the metal in place but the plate will start to lift away from the die as it is pulled inward. Take a nice planishing hammer and gently tap the plate back down around the edge of the opening. This will help create a nice sharp edge on the piece and also keep the metal true to the shape.

Pillowed form complete, the plate is turned over
and the top is worked

Once you have pillowed the form to the desired height, you can reverse the set up ON THE OTHER SIDE of the die (flip the MDF/masonite AND brass) and work on the top of the form to create detail. The screw holes will only line up one way so unless you make some alignment marks you may have to play with it until it all fits back together. This is normal :-) Here John has drawn some lines he's going to chase. He used traditional metal chasing tools for this part.

First course- chasing line detail
In this photo John is also demonstrating
the WRONG way to wear your safety glasses :-)

A note about annealing: Typically, you want to pull the die-formed plate off and anneal in between courses, however, it really depends how quickly you are trying to push the  metal. You can bust through your plate if you let it get too work hardened while trying to push it too fast, especially in tight areas. So pay attention to how the metal is behaving and use your best judgment.

Pillowed and first line course chased

John pillowed the form, flipped it and chased the first course of line design before he annealed this piece.

More detail work- re-establishing the high parts

After he annealed, John flipped the piece back over and with Delrin and hard wood tools  he made (John likes Maple), he punched some of the height back into the un-chased areas. The wood/ delrin tools are non-marring so you get very nice soft pillowed forms this way. By working both sides you also increase the height difference in the design. John worked two courses of deepening the lines on one side and pushing the un-worked areas from the other.

Remember to true the edges periodically throughout the process

Increasing line detail from the back

More of the same as above

In order to create a sharper line detail on the front, John finished the demo by demonstrating how to push the channel of the line closer together from the back. This sharpens the line. He again used a traditional metal chasing tool rather than the Delrin/ wood tools.

Our in-process piece and a finished version

This is a great process for anyone who can't afford a hydraulic press and who doesn't want to mess with pitch. It's relatively immediate once the die is made. John said the dies last indefinitely if used properly. I suspect the only part of the die that may need replacing over time would be the brass plate.

There was a lot of inquiry about where to acquire Delrin rod for tool making. John likes the company McMaster Carr for Delrin and other tools/ materials.

Many thanks to John and to our wonderful Metalink coordinator, Ingrid Donaldson! If you are a local metalsmithh and would like to learn more about our group or get notices on our meetings/ demos, feel free to contact me.

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