Keycap Profiles

By Xah Lee. Date: . Last updated: .
keycap profile wh4ty-s900
keycap profiles
keycap profile Signature Plastics YFQps
keycap profile Signature Plastics
Cherry
Keyboards of Cherry brand (Cherry is a German company).
OEM
Original Equipment Manufacturer. It means, a typical cheap keyboard.
SA
“Spherical Angled”, from Signature Plastics (a USA company that makes keycaps).
DSA
From Signature Plastics. (DSA stand for DIN standard height, Spherical Angled)
keycap profile y3t9m
Keycap profile. Image by Jacobolus [image source https://geekhack.org/index.php?topic=68550]

Basically, key profile are of 2 types:

There are 3 shapes of keycap top:

Another issue, is how the key plate is shaped or arranged. There are 3 major cases:

Critical, is how key top is angled to the key stem (axis of the switch). If not orthogonal, it means the angle of attack is not aligned with key movement, therefore inefficient.

Another issue is how key stem is angled to the key plate.

keycap profile ms9x5-2
Keycap profile. Image by Jacobolus [image source https://geekhack.org/index.php?topic=68550]

uniform flat tops keycap profile ns3xg-s754x332
• Flat top keycaps. • Flat key plate. • Angle of attack aligned with stem.
Image by Jacobolus [image source https://geekhack.org/index.php?topic=68550]
keycap profile staircase zz78x-s696x359
• Flat top keycaps. • Staircase key plates. • Angle of attack aligned with stem.
Image by Jacobolus [image source https://geekhack.org/index.php?topic=68550]
high height angled flat top key profile kg86f-s752x333
• Flat but angled key top, each row different angle. • Flat key plate. • Angle of attack not aligned with stem.
Image by Jacobolus [image source https://geekhack.org/index.php?topic=68550]
low height  angled flat top  key profile bw64w-s778x321
• Flat but angled key top, all rows same angle. • Flat key plate. • Angle of attack not aligned with stem.
Image by Jacobolus [image source https://geekhack.org/index.php?topic=68550]
keycap profile rp457
Painstakingly constructed illustration of keycap profiles from existing keyboards. Image by Jacobolus [image source https://geekhack.org/index.php?topic=68550]

Spherical and Cylindrical

spherical and cylindrical keycaps qJMm-s900
Spherical and cylindrical keycaps tops [photo by Daniel beardsmore.]

Reference

Conclusion

I think the best key profile is uniform, flat, and concave top. Concave top helps your finger determine position of the key. Uniform is great for swapping keycaps.

Angled key tops are a hack, and non-uniform keycap profiles also a hack, and non-orthogonal stemp to plate angle also a hack. They are hacks to avoid having a curved key plate. They have this goal: for any key row, finger should hit the key top in a orthogonal way, and the direction of force should be parallel to the key stem, but not having a curved key plate. We should use a curved plate if one really want a ergonomic fit.

Keycaps

Xah Keyboard Guide