For the robotic xylophone we started by purchasing an inexpensive portable xylophone to harvest the tines, then we looked for interesting configurations of the tines that would span a whole octave (13 notes)
Original xylophone
These were some of the original ideas
the winning idea
When we settled on an interesting configuration we made some sketches for the base. The triangle on the top right was the winner.
Initial sketches
The next step was to make a cardboard mockup. Designed in illustrator and cut on the laser cutter. The bend in the center gave it some additional structure and interest.
We needed a secure way to mount the solenoids so we designed a 3D printable mount with a matching cut pattern on the wood:
Designed in Fusion 360
Printed using PLA
Cut pattern, distance between holes is 12.7mm. The notch at the bottom is to accommodate the wires.
<aside> 💡 Solenoids are 5V, 50grams of force, usually found as a14052800ux0914
</aside>
The final triangle was cut out of 1/4" walnut veneer plywood with some additional structure made out of birch plywood. You can see the solenoid mount details front and back.
For the electronics that actuate the solenoids we are roughly following this Adafruit learning guide for a robotic solenoid. One of the important ideas from the guide was using the ULN2803 darlington driver (datasheet) for driving the solenoids.