Improving the slim-key Jankó

Discovering that the slim-key version of the Jankó was working so well really felt like a breakthrough! However, the previous version still had two issues:

1. The highest row had too much resistance and one had the feeling that when pressing a key, the force was directed into the wrong direction.

2. The keys of the lowest row were too long, exceeding the original keys by too much, they had too low resistance and too long key travel.

So I started thinking about ways to solve these problems. The first thing I noticed was that with the thin keys, one has the option to place one's finger in between two neighboring keys. In this way, for each key, in addition to the 3cm that are easily accessible, one gets additional 3cm between the two neighbors, so in total 6cm. This yields quite some flexibility, e.g, to play the pinky and thumb in the same row, even for large chords. After some time, I realized that this fact actually made it possible that play all chord shapes and scale fingerings with only three rows each, so one would in total only need four rows to play everything in all keys.

Only needing four rows had several advantages:

1. The total hight of the keys is decreased by 1cm, partly solving problem 1 (high resistance of highest row).

2. The total length of the keys is decreased by 3cm, solving problem 2 (low resistance and long key travel of lowest row).

3. Looking at four instead of five rows makes it easier for the brain to visually process what is is seeing.

4. Having fewer options where to hit a key reduces complexity.

What remained was the problem that playing on the high first row, one had the feeling that the force one applied to a key is somehow directed into the wrong direction and is not fully used to move the key. I realized that this was simply physics: Each piano key rotates around its fulcrum (see picture below). When pressing a white key at the front at its starting point, then the force is (almost) perpendicular to its rotation axis around the fulcrum. Thus, the force is used maximally for rotating the key, and almost no force is lost. However, when increasing the key height (as with the highest Jankó row) and keeping the key straight, then the force applied to the key is not perpendicular to its rotation axis anymore, and thus, quite a bit of the force is lost and not used for rotating the key. The simple solution to this problem was to tilt the keys, especially the higher ones, so that when pressing on its surface, the force would again be (approximately) perpendicular to the rotation axis.

While designing this new key shape, I deepened my friendship with Jankó piano maker Peter Reinert (see next post). He helped me model and cut the new key shape with a 3D wood router. The result looked very promising and the tilting of the keys had the desired effect: The highest rows were indeed feeling much better. We were definitely going into the right direction! But I noticed that I was a bit too careful with the angle of the keys of the highest row, the positive effect of tilting the keys could be increased even more. And the last thing that I didn't really like so much where the wide gaps between the keys of the first row. So the journey of exploration and optimization would continue...