Welding a custom bike chain ring

I had an interesting custom order recently, for a bicycle chain ring in a custom size. As a set of closed links, there's only one ring size possible with standard chain, and it's very small -- about 5 3/4. To make a custom size, I'd have to weld the links closed.

I started by turning a sizing guide in a piece of 2x4, and then wrapped a length of chain around it to see where cuts would be needed.

There was an excess section of inner link that was preventing the ring from closing around the form. I removed that material on the grinder until the ring could close, and then rounded off the corners.

The next step was to remove part of the extra outer link, but leave a section in place to be welded. I cut it off with a hacksaw and checked the fit again.

That's about right. I reshaped the cut edge of the outer link on the grinder before welding.

Here is the custom ring, ready for welding.

With the link welded closed at the correct angle, the ring is ready to wear.

This one was too big for any of my fingers, but it made a good thumb ring.

These rings are available made to order in my shop, here: hardwareaesthetic.etsy.com

Prototyping a percussion instrument, continued

With the top glued to the curved shell, I could try to tune the tongues. I started by relieving the hinge areas, which tends to lower the pitch and improve the tone at the expense of volume. I used a chisel to pare away material.

It went too easily, and I removed too much material from the hinge of several tongues. Wanting to raise their pitch, I also removed some material from the ends and edges. It worked to raise the pitch, but also made the pitch less specific and the tone more hollow. So there's a technique to avoid.

I continued to refine the sound as well as I could, and then cut a bottom from a handy piece of finish plywood, too thick to resonate well but enough for a proof of concept.

I glued the bottom to the assembly.

When the glue dried, I made a pass around the bottom with a flush-trimming router bit to bring it in line with the shell, and then played it a bit with superball mallets.

So how does it sound? Well, promising at best. I plan to make another at some point and correct these problems:

• Tune and free the hinges cautiously, and avoid trimming the ends or edges of the tongues.
• Make a shell that resonates. The kerfed sides of this one are effective sound-deadeners.
• Use a thin, solid back that can resonate.

When I make those improvements, it will be easier to tell whether this is a dead end or a promising direction. I'm still interested to find out.