Step 2: The box/resonator of the Thumb Piano
The box in this simple Mbira (thumb piano) is rectangular and easy to get right. It has 6 sides: 2 faces and 4 walls.
I used a scrap piece of plywood for the box parts and while it is not a very attractive-looking wood, it still worked well and I was pleased with the result. I have marked the dimensions I used in the first picture, but you may use any dimensions you like. I had to make mine small because the metal I had available for the tines limited the size of the instrument.
The shapes are pretty straightforward and easy to achieve, I used a hacksaw and some sandpaper to get them to the desired shape.
Cut the 6 rectangles from your sheet/board, then smooth off the edges and make sure that they are straight and that the walls are all the same height.
Only ONE of the 2 faces must had a hole in it. This hole should be placed just below halfway down on the face, as shown in the first picture. To make this hole, I drilled 8 holes in a circular pattern into the wood, then broke out the wood in the middle. Then I used a dremel tool with sandpaper (Picture 3) to enlarge the hole and make it look neat.
Once you have trimmed the pieces to all fit together, place them together and make sure that everything looks tidy. Glue the walls onto the BOTTOM face (the one without a hole in it) and leave the glue to dry. Cut 4 small triangles (optional, for extra strength) and glue them into the corners of the box to hold the walls at 90 degrees to one another. This should make it more difficult to break if the Mbira is dropped.
Do NOT glue the front face on yet!
While we wait for the glue to dry, let’s make the tines…
Step 3: The Tines (Keys)
Mbiras use tines to generate sound vibrations, in the same way a guitar uses strings. Each tine produces a different pitched note and they are arranged in this Mbira from lowest in the middle to highest at the sides. This makes the instrument easier to play.
This particular one uses 8 tines, however you may choose how many you would like to have.
I did not take pictures of the flattening process because it requires two hands, but the basic idea is to put a piece of wire or a spring-steel strip onto an anvil or another solid metal object, and strike it with a hammer so that it flattens between the hammer and the metal. In my Mbira I used a strip of spring steel so there was no need to flatten it, I just prefer the look of flattened ones.
Once it is “flared” out at one end (the end that will be plucked by your thumbs), sand or file it so that it is smooth and looks uniform. This will make it easier to play for longer without hurting your fingers.
The lengths of my 8 tines from left to right were:
45 mm 1
55 mm 2
62 mm 3
58 mm 4
60 mm 5
56 mm 6
52 mm 7
46 mm 8
The tines are mounted with a different length sticking out of the top for each one, so that allows tines of the same length to generate different sounds. Take note of the placement of the tines in the other steps.