This Wood-and-Copper Piano Hides an Electronic Heart, Turning Stepper Motors Into a Click Organ

Pseudonymous maker "thisisnomine," hereafter simply "Nomine," has built a piano with a difference: the attractive wooden machine makes sound using stepper motors, rather than hammers hitting strings.

"This was inspired by a number of projects people have made that consist of motors programmed to spin at different speeds to play music. However, very few allow a user to play them like an instrument," Nomine explains. "Instead, they are all pre-set songs, where notes were instructed to play for a certain period of time and the user would simply hit a button to start a song. I wanted to create something that looked and felt like an instrument, but secretly had an electronic skeleton."

That instrument is undeniably eye-catching from the outside: its oval body, with a large hole in the middle for the sound to escape, is decorated with four half-spheres above a piano keyboard made from circular copper buttons. Built from sapele wood and anigre veneer, its housing aims to mirror the aesthetics of a stringed instrument — and also, its creator admits, "does a good job of hiding the tangle of wires that lurk underneath the keyboard."

The outside of the instrument might be wood, but its innards are all electronic: two Adafruit MPR121 12-key capacitive touch-sensor breakout boards are connected to the keyboard keys, while the half-spheres connect to a quartet of NEMA 17 stepper motors connected to A4988 drivers. Everything is then controlled by an Adafruit Metro Mini 328-5V board — turning a touch of each copper key into a rotation of the motors.

"When music is made traditionally, the sound is generated by something (either a string, a reed, or a membrane) vibrating at a certain frequency," Nomine explains. "The frequency is what determines the note, a higher frequency being a high note (like a flute), and a low frequency being a low note (like a tuba).

"This is the same concept that allows the stepper motors to create music. The speed at which they spin controls the frequency of the 'clicks' generated by the steps, which means when the motor is spinning slowly it creates a low note, and the faster it spins the higher the note gets."

Nomine has published a full write-up to Instructables, including the project's source code — though without a wiring diagram, "because when I was creating this instrument I didn't write [it] down, and it has now been many months."