Thumb Piano

By RP Collier
Category: Craft, Music
Difficulty: Easy

The thumb piano, known as a kalimba, mbira, and by many other names, is a lamellaphone that uses prongs called tongues, keys, or tines that you pluck to generate acoustic vibrations. The length of the tine determines the pitch.

Generally, the thumb piano uses some kind of mechanism as an anchor that puts a great deal of pressure over the tines and across 2 bridges, leaving the free lengths of the tines room to vibrate. The tines are usually of the same material and gauge (thickness) to ensure that the pressure is distributed equally, holding everything in place and in tune.

The method shown here is simplified and wonderfully versatile. It allows the use of more fragile, delicate, and unusual materials for the body of the instrument, and it provides a way to use oddly shaped tines of different materials while at the same time permitting the tines to be swapped out and tuned with ease.

I’ve included 2 materials lists: a generic list and one that is specific to the salad bowl kalimba shown here. Experiment, explore, and find configurations that work for you.

The tines in the video are made of (from left to right): blue tempered spring steel, hairpin, street sweeper bristle, unknown steel lattice debris, electrician’s snake, knitting needle, street sweeper bristle, bicycle spoke, spring steel, umbrella rib, plastic hobby/craft brush, and plain steel wire with the end splayed by hammering.

The length of a tine determines its pitch. To tune a tine, loosen its screw, scoot it forward or backward a bit, retighten, and plunk.

Parts
/
Tools

Grounding bar (1) from the electrical section of a hardware store
Piano body (1) Examples here include a salad bowl, cigar box lid, wooden box, and aluminum block. You can use almost anything that’s easy to hold and strong enough to withstand the fastening of a grounding bar and possibly a shim. Hollow or thin materials are good sound resonators; if your chosen body material doesn’t resonate well, attach a resonator.
Shim, (if needed) (1) can be a chunk of wood, metal, or plastic, 3/8' thick or thicker
Fasteners (1) such as hex screws, machine screws, wood screws, or nails
Tines (1) from a material firm enough to vibrate when plucked, up to ¼' wide: hairpins, wire, bicycle spokes, umbrella ribs, teriyaki skewers, knitting needles, street sweeper bristles, etc.
Grounding bar, (for salad bowl thumb piano), 4¾' long (1) from the electrical section of a hardware store
Salad bowl, (for salad bowl thumb piano), wooden (1)
Square dowel, (for salad bowl thumb piano), 3/8' hardwood (1)
Spring steel, (for salad bowl thumb piano), .032' thick × 1' wide, 60' long (1) from your local industrial steel distributor, trimmed to various lengths from 2' minimum to 6' maximum
Wood screws, (for salad bowl thumb piano), #8, 1¼' long (3)

Drill bit up to ¼"
Hacksaw to trim tines and, if desired, the shim. A hammer can be used instead of a saw to trim spring steel tines — clamp the tine in a vise and strike to bend it until it breaks. Wear eye protection!
Hand drill
Screwdrivers flat blade or Robertson bit for the grounding bar, and whatever type is needed for your chosen fasteners (including hex key)

Steps

Step #1: Fasten the grounding bar.

The grounding bar is used by electricians to ground house circuit wires. It comes in various lengths and can be found in most local hardware stores or builder/contractor supply centers. The empty slots (2, 3, or more) come drilled all the way through — this is where fasteners can be used to attach the bar to something. But you may need to drill through if your slots aren’t in the perfect places.
To anchor the grounding bar, simply make 3 holes with a hand drill into the surface you’ve chosen to be the body of the instrument. The screws shown in the bottom photo are hex head 10-32 machine screws (smaller and different types of machine screws could be used) secured with T-nuts, speed nuts, or standard nuts with lock washers and fender washers. If screwing into metal, you can use a tap to thread the holes.
If you’re going to mount the bar on wood or thin metal such as a tin can, you may need only a hammer and nail to make the 3 holes. With wood, just use wood screws or something similar. Nails alone might possibly do the job with a bit of wood glue — start the holes with a nail, and add a bit of glue to the holes before driving them firmly. Heavy-duty epoxy, riveting, welding, or even slotting a surface with a milling machine or router are some other ways to anchor the bar.