DIY Digital Piano - 24 Key Prototype

This video gives a short overview of a 24 key piano prototype I built.

*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:

Lionel's video on piano key size:

More info on hand span and keyboard size at PASK (Pianists for Alternatively Sized Keyboards):

GitHub repository, containing firmware:

Pianoteq, used to generate the guitar sounds heard in the demo:

[RazzUK]

I come to this video over and over just to listen to the demo song, it's so beautiful

[JamesGiannoni]

Wow. The expression and sensitivity with which you play honestly shocked me. Was not expecting that haha.

[muutamuuta]

i just started learning the piano a month ago as a female adult with very small hands, been obsessed with researching about narrow key digital pianos after watching "piano's darkest secret". Narrow keys, Kaduk...etc, the former you have to be on waitlist, the later has their pre-order closed and seems still in pre-production stage. Very frustrating to be googling for hours with no luck. So I got to the point thinking "fk it i'm gonna build my own." AND THEN I saw your video!! Looks absolutely promising and most importantly, your effort and spirit is truly inspiring, what you're doing is truly wonderful, fulll respect! I'm gonna start tinkering, super hyped! You're awesome!

[mio]

awesome! I'm dreaming about playing ninths with one hand since forever. so cool!

[戴珞亞]

So glad you’ve proceeded to create what you’ve always wanted to. Really beautiful work Andrew and it’s so lovely to hear you play again!

[gguitarwilly]

On my acoustic Janko piano I used folded lead sheet as weights. Lead is about 1.5 times heavier than the nails you use, so you could decrease the bulk of the weights.

[flywittzbeats]

Incredible…. I fully thought you would need either an analog input or two digital inputs to read a time based velocity, but this is super enlightening! Thank you so much for showing this awesome project!

[shahenohanjanyan]

Andrew this is epic, thank you so much for this project

[Lucius_Chiaraviglio]

Even better for small hands (especially for people who haven't gotten used to the Halberstadt layout yet): Use an isomorphic/generalized layout. Also good for tuning systems other than 12 notes per octave. If you're sticking to 12 notes per octave, harmonic table lets you play 3 note triad chords with 1 finger.

[isaiahhiggins]

Very cool project! I'm building an organ foot pedal with binary hall effect sensors, so it's interesting to see how much finesse the linear sensors are capable of! As a side note, I have those same 1/4" jacks and never thought to arrange them diagonally to fit a breadboard. Great stuff!

[Planthier]

Nice work, bravo !
I would like to create one day a microtonal DIY midi piano 😅

[samuelvink]

Congratulations! That’s quite impressive

[charliemopps]

I wonder if rather than using weights, you could use the magnets on they keys... and then have an Arduino controlled electro magnet in place to resist it. You're already detecting the magnets movement... so then all you'd need is to modify the electro magnets current to control the key press resistance to mimic a real key. You're already doing the physics calculation as well so... By doing it that way, you could make the entire thing significantly lighter and maybe even smaller.

[paulromsky]

I have average size hands but I could stand to lose a few pounds (which would thin out my fingers too). So I couldn't go with narrower keys, and if I went with wider keys I would not be able to span an octave and a Major 3rd. But, if I could make the black keys a millimeter or so thinner, I could hit the whites deeply without grabbing a black key from time to time.

[theopinionmachine]

Seems like this would be an affordable diy to add midi to an acoustic piano. I have a QRS product that does that for my rhodes but it wasn’t cheap and I got it used.

[andy-simmons]

Man this is so cool! Does the action remind you of anything else you’ve played, or is it a pretty unique feel? Seems like you can play pretty expressively with it. Great job!

[Poulscath]

Very very cool. I really want to do this.
Btw, have you seen how harpsichord keyboards use decorative plates at the front of the keys? It could be useful for hiding the rough cut ends.

[awanegenebayo]

Great work ! What is the name of the piece you are playing at the beginning ?

[Hvranq]

Have you ever considered to use hall sensors for velocity sensitivity?

[jackisgoofingoff]

Wanna know more about the hardware / hammer design