Build Your Own Arduino-Controlled, Velocity-Sensitive MIDI Keyboard

You can purchase a MIDI keyboard for as little as $30, or for as much as a few thousand dollars. As with anything else, the price comes down to the quality of construction and components, the features it has, and branding. A basic MIDI keyboard is little more than a few dozen buttons with an interface to connect to your computer. Those cheap MIDI keyboards feel nothing like a real piano, and that can have a serious effect on how well you play. For a school project, Redditor Learly_songs designed a 3D-printable, Arduino-controlled keyboard that you can build yourself, and it features velocity-sensitive keys.

If you’ve ever played a piano, you know that the force you use to strike the key is important. If your MIDI keyboard just has basic buttons, it can’t respond to the amount of force you use; the buttons are binary, and are either simply on or off. Learly_songs used two buttons for each key in order to make the MIDI keyboard sensitive to velocity. Those are regular tactile momentary push buttons, but they’re staggered so that one is pushed into the “on” position slightly before the other. By timing the difference between when the each button is activated, the velocity can be calculated and used by the MIDI software to alter the volume and sustain of a note.

They keys are all designed to be 3D-printed and the frame is made from a combination of 3D-printed and laser-cut parts. The buttons are all monitored by an Arduino Mega clone. That board was chosen because it has a lot of usable I/O pins, which are necessary for all of those buttons. Learly_songs programmed the Arduino themselves so that it will act as a standard MIDI keyboard. They haven’t released the files for the 3D-printable parts quite yet, but the plan is to sell a kit with the electronics and then make those 3D part files open source. You’ll want to follow them on Reddit to find out when those become available.