Blister

The shape of the hammer-form I chose was one of the pointier ones, so it was hard to get a lot of depth on the blister. On the plus side, using a set-up like this seems like a versatile technique that offers a lot of control over the workpiece. It would require some foresight to get the intended results though, but I get the sense that a mentality of looking ahead and thinking about how the material will behave applies to all hammer-forming methods.

I used a jigsaw to prepare the two CNC-milled MDF hammer-forms, then flat and round files to clean up the edges. I had some initial concerns about tightening the screws to secure the blank: they were countersunk, but there was no countersinking in the MDF. It worked out when I tightened them, though, as doing that caused the soft MDF to compress and make the screws sit flush.

The shaping of the metal felt like shaping the bowl, but with less support. I used less force so the aluminium doesn’t split. I moved the pointy end of an egg-shaped nylon mallet around while hitting it with a steel ballpeen hammer, trying to deepen the blister.

When I realised it couldn’t go much deeper due to the sharp end of the hammer-form being at such a steep angle, I made some corking tools from MDF cut-outs on the bobbin sander and disc sander. The corking tools were useful for defining the edges more clearly, and adding depth to the pointy end of the hammer-form. But the material qualities of MDF made them fall apart very quickly, especially the thinner ones.

MDF is not well-suited to this application.

I looked for some pine or other soft wood to create corking tools out of, but couldn’t find any small pieces. Fortunately, a colleague had already taken the small pieces of wood I was looking for and made some corking tools out of them. I asked to borrow them, and they helped greatly with smoothing out the bowl. These were vastly superior to the weedy MDF ones I created. The striking surface didn’t split like the MDF had, and were much nicer to hold due to the peg-like shape. They were like the ones made from wooden dowels by Eric Griffith, featured on Scout.com. I found the ones with a long striking surface (like a line) were the most versatile, as they could be used to define edges, or work across curves in a sweeping action.

This one was really effective at moving metal.

I needed a bigger variety of corking tools, so I found a piece of wood that looked like it was turned on the lathe. It was perfect for making a bowl-shaper, and I used the disc sander and some sandpaper to get it to a nice dome. I also made a small corking tool from a tiny piece of laser-cut MDF, which didn’t last long at all, even when reinforced with tape. I continued to smooth out the blister with the variety of corking tools. I noticed that the tools made from actual wood were much more effective than those made from MDF. They didn't seem to absorb the force of the hammer as much, and therefore took less energy and time to use.

The domed wooden corking tool worked really well.

The tiny MDF corking tool was destroyed almost immediately.

I couldn’t get the blister to a level of smoothness I’m happy with, probably because of the shallowness of the ‘bowl’ and the tapering-off. I took it out of the hammer-form and traced the shape of a spoon handle around it, taking advantage of the taper from the bowl to the handle. I cut it out with the guillotine, then a pair of tin-snips. Though I wanted to eliminate the flange around the bowl of the spoon, I didn’t want to scratch the underside with the tin-snips. It looked decent with a slight lip anyway, and the overall form reminded me of a Chinese soup spoon.

I used a variety of files and the domed corking tool as a block for some 80-grit sandpaper to even out the flange. I cleaned the edge up with some 400-grit, and polished the whole thing with Brasso. After all this, I put a bend in the handle of the spoon, serving as a kind of rest. When you put the spoon down on a flat surface, the bend will ensure it sits level. It prevents the spoon from sliding into a bowl, a common issue has been alleviated in a similar way in some soup and serving spoons. It works well for drying, too.

Apart from a Chinese soup spoon, the form reminds me of woodworker Ariele Alasko’s carved spoons. The technique feels very versatile, as it’s a bit of a counterpart to the way the tray was made. However, it feels necessary to be aware of how deep you can get the metal to go, based on the size and shape of the hammer-form. Colleagues with rounder hammer-forms could get the workpiece to be deeper and smoother. Much of the difficulty came from trying to work the thin parts of the form, which turned out to be shallow and quite lumpy.

This exercise was a good introduction into how the hammer-forming process can be guided by CAD. But perhaps I’ll try making a blister without such a dramatic taper next time.

It behaves like a normal spoon.

Underside of the spoon.