Project Information
This is based on a marumba box, rumba box, mbira, marimbula, bass kalimba that I saw on holiday years ago. It's a substitute for a standup bass.
I'm told that in the Caribbean, they originally made the "twangers" out of shipping straps or old victrola springs. I chose to to try poplar sticks and they work quite well. I tried cutting up a saw but my wife preferred the brighter sound of the poplar. Sizing the twangers is just by trial and error. I tapered mine towards the tips and smoothed/rounded them so that they don't make a thwacking noise as they leave the finger. Use carriage bolts set into a thin strip of maple on the inside of the box, so that they don't spin as you turn the wingnuts. Alternately, you could put "T" nuts on the inside and tune it with the bolt heads on the outside.
Her's a link to the construction plans I more or less followed:
http://www.dennishavlena.com/bk.gif
I used 1×8 pine boards but will use 1×10s next time to make it deeper and less tippy (important, since people mostly play it in casual jam scenarios, with a beer in one hand). I rabbeted the corners and reenforced them with glue blocks. I was using this as a hand tool practise project, so I rabbeted the edges as well and set the panel into it. The sound board is a piece of 2'x2' poplar ply from HD (but you need to choose carefully because some HD stores carry a similar poplar sheet but it has a pressboard interior layer that doesn't work well. You want to look at the side of the ply to see actual wood in there. It should make a pretty loud "bong" when you tap it. I'll add a couple more holes to the sound board on the next one.
I cut up and old belt for the handle.
If you want to try steel twangers, I've found that the best/safest technique for cutting up a saw is to clamp the saw in a bowed position and score out the lines with the edge of a file. You probably need to get about a 1/4 way through the saw plate. Then you can put the saw into a machinist's vise and crack the metal along the score mark the way you would if you were cutting glass.
I'm told that in the Caribbean, they originally made the "twangers" out of shipping straps or old victrola springs. I chose to to try poplar sticks and they work quite well. I tried cutting up a saw but my wife preferred the brighter sound of the poplar. Sizing the twangers is just by trial and error. I tapered mine towards the tips and smoothed/rounded them so that they don't make a thwacking noise as they leave the finger. Use carriage bolts set into a thin strip of maple on the inside of the box, so that they don't spin as you turn the wingnuts. Alternately, you could put "T" nuts on the inside and tune it with the bolt heads on the outside.
Her's a link to the construction plans I more or less followed:
http://www.dennishavlena.com/bk.gif
I used 1×8 pine boards but will use 1×10s next time to make it deeper and less tippy (important, since people mostly play it in casual jam scenarios, with a beer in one hand). I rabbeted the corners and reenforced them with glue blocks. I was using this as a hand tool practise project, so I rabbeted the edges as well and set the panel into it. The sound board is a piece of 2'x2' poplar ply from HD (but you need to choose carefully because some HD stores carry a similar poplar sheet but it has a pressboard interior layer that doesn't work well. You want to look at the side of the ply to see actual wood in there. It should make a pretty loud "bong" when you tap it. I'll add a couple more holes to the sound board on the next one.
I cut up and old belt for the handle.
If you want to try steel twangers, I've found that the best/safest technique for cutting up a saw is to clamp the saw in a bowed position and score out the lines with the edge of a file. You probably need to get about a 1/4 way through the saw plate. Then you can put the saw into a machinist's vise and crack the metal along the score mark the way you would if you were cutting glass.
