DIY Digital Piano - 24 Key Prototype

This video gives a short overview of my latest digital piano prototype.

A few details that I didn't mention in the video:
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**Key size**
I mention that the keys are smaller, but not that they are specifically 7/8ths the width of normal keys. I was worried about my fingers fitting between the black keys, due to the smaller gap. The upper octave uses narrower sharps that are 6mm wide. In the final version, I will keep the 6mm wide sharps. I also experimented with some different spacings - the buttons don't need to be screwed to the keysticks exactly centred, enabling the intentional offsetting of black keys to the left or right.
Here I should also mention that I can reach a tenth from the edge of the keys on a normal size keyboard, so I don't actually have particularly small hands - but it just so happens that the piano key width settled on as standard is on the large side, and the majority of adults would benefit from narrower keys. On this prototype, I can easily play 10ths without needing to be at the edge of the keys or roll/split!

**Black key tops**
These are also laser cut, on their sides.

**Pins**
The pins are available cheaply on aliexpress, they are 3mm wide stainless steel dowels. These were easier to source and cheaper than 'proper' piano pins.

**Tools**
The only power tools I needed were a table saw and a drill press. Earlier versions had keys laser cut in one piece, but once I moved to a new job and lost access to free laser cutting, I realized how expensive this is (largely due to the thickness of the material). I initially considered using a bandsaw to cut out the keys jigsaw style, as is typically the case in keyboard construction, but I eventually decided upon the current design, which has keysticks cut out on a table saw. I found this very efficient.

**Changes in the next version**
There are a few changes I intend on making, including:
- Distributing the counterweights between top and bottom of the keysticks.
- Moving the electronics to sit under the front of the keys, rather than the rear.
- Modifying firmware and/or hardware to better cope with expression for very fast key presses, and eliminate some extra very soft notes that are produced due to noise.
- Moving from breadboard based electronics to using a PCB fabrication service.

**Pianoteq preset**
The preset used is 'Classical Guitar Gentle', but with a foot pedal controlling the plucking point, and a velocity curve that favours low velocities.

Some links:
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The first 5 key prototype, with two keys connected to electronics:
Laser Cut Piano: Two Keys

Lionel's video on piano key size:
Piano's Darkest Secret

More info on hand span and keyboard size at PASK (Pianists for Alternatively Sized Keyboards):
https://paskpiano.org/

GitHub repository, containing firmware:
https://github.com/aleathwick/midi_ha...

Pianoteq, used to generate the guitar sounds heard in the demo:
https://www.modartt.com/