A working 3D printed piano action built by Brian Yu of Dovetail has taken shape after six months of designing, prototyping, and fabricating, according to The Awesomer, and the result is a hybrid instrument that sits somewhere between a digital piano and a fully analogue one.
The piano action is, when you sit down and think about it, one of the more elegant mechanical solutions in the history of instrument-making. A single key press has to control hammer velocity with precision, stop the hammer from resting against the string, ensure the hammer rebounds cleanly without a second accidental strike, allow rapid repeated notes, and lift the damper while the key is held before dropping it again on release. That list of requirements took around 150 years to refine into the mechanism most players recognise today. Yu set out to replicate it in a matter of weeks using a 3D printer.
Compliant Mechanisms Carry the Load
The design relies on compliant mechanisms: solid printed parts engineered to flex in specific, controlled ways rather than relying on separate hinges or pivot points. It is the kind of approach that rewards careful iteration, and the 3D printed piano action went through many rounds of refinement before all the physical sensations of a real action were faithfully reproduced in plastic. Getting the feel right matters here. A piano player’s fingers are extraordinarily sensitive to the response of the action beneath them, and any shortcut tends to announce itself immediately.
Because a piano has more than one key, Yu also had to engineer a modular system to connect everything together. The modularity carries through to the electronics: a set of PCBs daisy-chained together, each supporting a group of keys. Infrared sensors track key movement, feeding data out as MIDI signals, which means the instrument behaves as a MIDI keyboard with real mechanical action rather than the typical rubber-dome or weighted-hammer approximations found in most digital instruments.
Prototype Shown at Open Sauce
The 3D printed piano action made its public debut at Open Sauce, where a number of musicians were able to sit down and try it. As a prototype it still carries a few rough edges: Yu plans to swap the infrared sensors for hall-effect sensors, improve the action itself, and experiment with a different filament. Hall-effect sensors, which detect position using magnetic fields rather than light, should give more consistent and reliable readings across the full range of keys.
The six months Yu invested in the project, as reported by The Awesomer, reflects just how much mechanical nuance a convincing piano action demands. Every moving part in a traditional grand action, the wippen, the repetition lever, the hammer butt and its spring, all exist to solve a specific physical problem. Translating those solutions into compliant printed geometry, without the option of separate machined components or the accumulated wisdom of a specialist manufacturer, is a genuinely involved engineering problem.
The goal, as Yu describes it, is a feel that lands somewhere between a digital piano and a fully analogue one, not trying to perfectly replicate a Steinway concert grand, but offering something more physically engaging than a standard keyboard controller. Whether the final filament choice and the revised sensors close that gap further is something Yu says will be addressed in future videos.
For anyone who has spent time trying to coax expressive playing out of a stiff MIDI controller, the ambition is easy to understand. The 3D printed piano action is a prototype, but it is already asking the right questions about what a printable instrument can genuinely feel like to play.
