Build Instructions

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• 1

  Step 1

  Building the box

  It's important to have an airtight box aside from the sound hole(s). It's good to get all the joints as solid as you can get them. I believe, the more uniform the material, the better it will be able resonate. I designed this with a removable back and bike inner tube gasket for serviceability, but if I wanted a better sound, I could have sealed the bottom permanently. Fortunately, with the effects and amplification added, it's not too important to get the design perfect. It's important that the area around the bridge is perfectly flat, otherwise you'll have buzzy tongs.

  It's made of discarded acrylic, laser cut with a 30w engraving machine. I used an online tool to generate an SVG for a basic box, and finished the design work in Inkscape(a real pain for CAD-type work). Next time, I'd like to design in a cad program. The fractal sound hole was designed in ContextFree. The current design files do not include holes for the teensy, battery holder, or power switch. I had to drill those on this version.

  I epoxied 3 of the pieces together first, then 2 more, then the back plate, simply holding them together until the 5 min epoxy cured enough. Next time, I'd like to get a longer working time epoxy and use clamps or elastic to keep it held together.

• 2

  Step 2

  Building the bridge

  The bridge is made from 2 pieces of scrap hardwood that I dumpstered. They needed to be as flat and strong as possible. First I marked one of the pieces by holding it up to the holes etched through the box. I drilled a hole the size of the bolt through both pieces of wood. Then I put the first bolt through to keep the wood aligned for the next holes. On the inside piece, I drilled halfway through with a larger bit, then, using an alan socket, I punched the hole into a hex shape for the nut to tighten against.

  With the bridge in place, I put a spacer against it so I could consistently run a file just below the bridge. This made a shallow notch for the steel welding rod(bench ground to length) to rest. It's important the notch is even and cups the rod well, so that the sound can transmit well.

• 3

  Step 3

  Making the tongs

  The tongs are made of this spring steel that some kalimba makers use from the website https://www.kalimbamagic.com/shop/accessories . In the future, I'll be trying to source the steel in bulk here in Portland, where I live. I've heard of people using the steel strips from auto wind shield wipers.

  The steel comes in a roll, so I started by bending that straight by hand. I made lengths of about 9cm to 14cm. To cut them, I used a bench grinder to make a notch. I immediately bent the metal at that notch and it broke away. I then smoothed each one out on the grinder. To get a second row of tongs up above, I used a bench vice to hold 3 tongs at a time at equal lengths while I used a block of wood to bend them evenly. I wanted to start with a bend about 1cm from the playing tip, then about 1cm further, make the opposite bend.

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