Building a Glass Marimba
These are the steps I took to build a 3 octave glass marimba (F3 - F6)
Please feel free to contact me with suggestions or questions.
Day one: picked up some 5mm plate glass.
Using scrap glass to experiment with widths. Width doesn't affect the pitch much, but it does change the tone (and harmonics) a lot.
Blanks are cut in three different widths.
The glass is tuned by shortening the length.
Sanding the edges with a rigged-up wet sander. The water keeps the glass from chipping and reduces glass dust. Ain't nobody got time for silicosis.
Fine tuning with a diamond wheel and again lots of water. I bet you're wondering how I took ths picture.
Safety and fashion go hand in hand.
It took a few days to sand and tune all the glass.
Next step is to cut the resonators. They will amplify the sound. Most of them will be 2" central vac pvc, and the larger ones are 3" sewer pipe.
Soaking the labels off the end caps are one of the most exciting tasks. I'll be sure to post the video.
The tubes are tuned by length. (Geek alert: when capped, the tube length is one quarter the length of the sound wave. They need to be a bit short (sharp) to account for 'end correction' at the top of the tube).
Fine tuning the tubes with a bandsaw.
Matching each tube with it's glass to make sure that the sound of the whole instrument is consistent. If the tube length is a bit off it can cancel the resonance and deaden the sound.
Cutting and tuning the tubes took a few days. Time for a pint.
Next step is the frame. I needed a really level surface, and I don't have a workshop, so off comes the bedroom door.
Lining up the glass bars to create a map. This will make the rest of the project a LOT easier.
The glass bars must rest on their wavelength nodes, which will determine the shape of the frame. There is a formula for finding the nodes (22.5% length), but a few salt tests confirm that the glass is behaving as expected. As you tap the glass, the salt lines up on the nodes. Are you still reading this?
The nodes are dotted on the map.
The rail positions are drawn up under the nodes.
Rails are cut to the right shape. The cat is wondering why he hasn't been fed in days.
Making the legs for the end pieces of the frame.
Legs and top supports are done.
Assembling the end pieces.
End pieces done. Wheels will go on later.
A second pair of eyes keeps things lined up. He is also too hungry to stand up.
Lining up the resonators on the map.
The tubes are joined by drilling holes in aluminum slats. A few bends in a vice are needed too.
Everything is assembled and it's a huge relief to know that it all lines up.
The process of sanding and varnishing the frame takes a few days. As it turns out, this is NOT VERY FUN.
Now the final touches. Wheels are attached, and some layers of foam rubber padding are put on the rails.
The glass bars are attached using adhesive foam weatherstripping.
And it's time to play!
If you build it, they will come. Maybe.
