It has long been known that a flat typing surface is not very comfortable. This is why the majority of keyboards have profiled keycaps. You may have noticed that all keycap profiles share a common characteristic: the overall typing surface is in the general shape of a curve.
(https://i.imgur.com/LM8NMvI.jpg)
(original photo from https://geekhack.org/index.php?topic=68550; check out that thread to see lots of other profiles)
Changing the keytop angles (in order to achieve a curved typing surface) has flaws:
- The angle of the force applied to the key is not in line with the translation axis of the switch. As a result:
- Only the component (https://www.physicsclassroom.com/class/vectors/u3l1d) of the force that is parallel to the switch action actually contributes to moving the switch. The operator therefore needs to press harder in order to move the switch the same amount (vs flat keytop):
(https://i.imgur.com/0hPlQGi.jpg)
- The perpendicular force component becomes friction. This results in a less smooth key travel.
- Additionally, the added friction resists the movement of the switch and makes the operator have to press even harder!
- The angled keycaps also need to be taller. The perpendicular force component therefore has greater leverage, which increases its added friction (which decreases smoothness and requires you to press even harder):
(https://i.imgur.com/EPcUFTg.jpg)
To fix these flaws, Curve0 has the switches themselves at an angle. This gives a curved typing surface with flat keycaps.
(https://i.imgur.com/hiin7KF.jpg)
Another advantage of having the switches at an angle is that your finger actually moves in the direction of the press during the key travel, which feels more comfortable (in my opinion at least).
With DSA keycaps, Curve0 will have a home row height of about 25.5mm and a spacebar height of about 27.5mm.
Measuring the angle is not as straightforward as other keyboards since each row has a different angle. With the default rubber feet, the home row has no angle (parallel to table). However, I find that the keyboard angle is better represented by the tangent of the curve between the home row and the row above it, as this is the center of the actual typing surface (without the spacebar row). This has an angle of 5°. Finally, the spacebar has an angle of 2°. The extra rubber feet add (or subtract, if you put them on the front) 4°.
(https://i.imgur.com/IZ2VbCo.jpeg)
(https://i.imgur.com/LON3qnS.jpeg)