Can you make a kalimba from stuff lying around your garage?
The short answer is yes, sort of.
The first point is that my woodworking skills and metalworking skills are pretty basic. And so are the tools I have available. That said, a kalimba seems a good starting project because they’re fairly simple, comprising of a body, a bridge and tines that vibrate to produce the notes.
My initial thinking is to use a piece of old wardrobe draw for the body, an old oven shelf for the tines and make a bridge from other draw parts. The body is easy, I’ve dismantled some old wardrobe drawers and I cut the side of one of these in half. I also add a piece of wood to raise the height of the bridge.
The bridge is designed to firmly hold the tines in place at one end and allow the free end to vibrate. There are a number of different configurations, I opt for a 3 part construction with 2 bridges and a cross bar.
The rear part is a piece of wood, the front part needs to be routed to fit a metal bar, I’ve seen this on a few kalimbas, presumably to help with resonance. I’ve only got a rotary tool for this and the first attempt doesn’t go well, as you can no doubt imagine a rotary tool always wants to fly off to the side rather than go in a straight line. A second attempt is much better. For the cross bar I use an old pencil drilled at both ends.
There’s a large variance in the number of tines used. 17 is common but so are smaller numbers – usually an odd number. I thought that 5 or 7 would be good for the size of the wood I’m using.
The physics behind tines is also far more complex than I’ve given credit to. The length is an important factor but so are properties like Young’s Modulus (essentially stiffness), material density and shape. You can choose an arbitrary length, work out the frequency of vibration and then use a formula to work out the length of tine you need for different notes in a scale. Formulas for length are based on the twelfth root of two which is an algebraic irrational number which represents a semitone in Western music, known as the twelve tone equal temperament.
Rather than spending time working out such formula, I decide upon lengths that seem about right for the size of the body and also let me get the best use out of the oven rack without too much wastage and I will sort out tuning later. Next I file the ends to smooth them off. Flat materials seem to vibrate better, I base this on the fact that you don’t often seen round tines.
This is where I encounter my first problem. I haven’t factored in the length of the bridge when considering tine length, I’ve made them far too short to use with this bridge.
So I have a rethink and need something that will hold the tines firmly but won’t reduce the length of them too much. An earthing block seems ideal, it has eight spaces with 2 fixing screws for each. Unfortunately I have to purchase one, cost is about £3 from Screwfix.
On assembly of the bridge and initial install of the tines I encounter a second problem. Although the tines are vibrating, so is the body. I have somehow not accounted for this basic principle of acoustic instruments which means that holding the instrument dampens pretty much all of the vibrations.
I decide to turn the body into a box which doesn’t go particularly well given my woodworking skills. The base is easy, it’s the other half of the side of the drawer I originally used. I use a very crude arrangement for the sides, it would be preferable to use better joins than right angles and fewer pieces would result in a better box, especially as I haven’t cut these very straight. But it assembles together, I drill some sound holes in the top. A stepped drill bit is ideal for this, it allows you to drill a small pilot hole and then use the stepped drill bit to easily increase it to the right size. At this point, something weird happens. I haven’t gripped the box adequately whilst drilling one of the sound holes and it spins round. Some of the screws from the earth block bridge have spun out of the holes and are nowhere to be found. On completion I find that the base isn’t quite flat which is really annoying, it could do with velcro or something to stop it moving when it’s on a surface. There are also a number of gaps which can’t help but it does resonate fairly well.
The third problem is tuning. It’s tuned to F Phrygian but tuning is incredibly difficult. Maybe it’s because I’m used to guitars and ukelekes, it feels like you need to be able to make micrometer adjustments with this for tuning. Tiny adjustments seem to make a big difference. Maybe it would be easy with a slightly larger bridge or flat tines, not sure.
But the project ultimately works, here’s a short video recorded on a phone so not the best sound quality and note me holding a corner down to stop it rocking.
It’s far from perfect but overall I’m really pleased how it’s come together. I’m thinking one possible option would be to fit a piezo disc so that I can amplify and apply effects, this is something for the future.
I’m also looking at building other instruments, noise boxes and electro-acoustic type instruments using recovered components as much as possible like fans, motors etc. Watch this space…..
