Experimenting with key shapes

The first Jankó keyboard we built only had four rows with 2x2cm keys. After a while I realized that four rows with so small keys was simply not enough. My thumb was constantly missing an extra row. So our next project should be a Jankó overlay with the original six rows. Since the rows are build in steps, six rows would mean quite a lot of height difference between the first and the last row. In particular the highest row would be quite difficult to play. I thought about a construction that reduces the height difference between rows while avoiding the keys to touch each other when being depressed.

My idea was to make the wooden sticks only 5mm wide instead of 10mm so that the keys would fit in between two neighboring sticks. I used this technique and built a prototype with six rows but quickly realized that having so many rows made the whole construction quite fragile, the last row was still pretty high and there was a huge difference in resistance between the first and the last row.

I therefore went back to only having four rows but I wanted to increase the key length instead. For playing scales it seemed to be beneficial to be able to play the thumb and the longer fingers in one row, so I tested on a piece of paper how long the keys should be to allow this technique.

I settled for a compromise of having 4cm key length for the two middle rows to apply the thumb technique and only 3cm for the first and last row, thus limiting the total length of the whole key.

After having decided on the key layout, the building process could start. The first step would be to bring the keys to regular alternating height, where the height difference between two neighboring keys would always be 5mm.

Next step was gluing the long 5mm wide sticks on top that would form the basis for the different rows.

After having lacquered the key tops, we could start gluing them on the sticks. We first glued the first two rows and then added little wooden blocks that served as steps for the third and fourth row.

Only having 5mm for gluing the sticks on top of each other was quite challenging and I was a bit skeptical whether the glue was strong enough. But its power surprised me once more and also months later the keys are still super solid. We finished the last two rows and our fourth homemade Jankó was done!

When I played this Jankó I had the feeling that we finally reached a level, where it doesn't feel like a cheap improvised experiment but like a real instrument.

My idea to have 4cm keys to allow the thumb to play in the same row as the longer fingers actually worked and simplified playing scales. On the other hand, the distance between the first and the third as well as between the second and the fourth row became quite large. Playing certain chords and scales thus became somewhat inconvenient. So again, the keyboard felt a bit like a compromise and I realized that we still hadn't reached our goal. But nevertheless, the keyboard actually felt pretty good and was inspiring to play on.