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Model F buckling springs were still a cost-reduced inferior replacement for beam springs¹, which themselves were a decent but imperfect attempt to imitate the b

by kps 9y ago

Model F buckling springs were still a cost-reduced inferior replacement for beam springs¹, which themselves were a decent but imperfect attempt to imitate the best key feel in the history of the universe, the Selectric. ¹ https://deskthority.net/wiki/Beam_spring https://deskthority.net/wiki/Beam_spring Edit: It's not entirely correct to blame cost-reduction alone for the end of the beam springs. ISO 9241 killed the existing beam spring switches, and making the replacements equally good (or better — they did suffer from wobble) would have been expensive.

efm 9y ago
What mechanism did the Selectric use?
- dwringer 9y ago
  "When the typist presses a key, a pawl on the key lever depresses a matching metal bar (interposer) for that key. The interposer, which is oriented front to back in the machine, has one or more short projections (lugs) protruding from its bottom edge. Each interposer has a unique combination of lugs, corresponding to the binary code for the desired character. Each interposer also has a tab that slots in between loose steel balls in a race, the size of balls and race selected precisely to leave a total gap barely larger than the width of the interposer tab, such that only one interposer tab can fit in the free space and thus only one letter can be selected at a time." [1][2] Not exactly comparable to the one on a modern PC, I guess. [1] https://en.wikipedia.org/wiki/IBM_Selectric_typewriter#Selectric_mechanism https://en.wikipedia.org/wiki/IBM_Selectric_typewriter#Selec... [2] https://www.youtube.com/watch?v=uTjxwVfx8GA https://www.youtube.com/watch?v=uTjxwVfx8GA
  - kps 9y ago
    The Selectric feel was particularly good in a few ways: - it had a very light pre-pre-travel of a millimetre or so, providing distinct touching-but-not-pressing feedback; - the force drop at the tactile snap point was so high it felt like the keyboard was actively trying to help you type; - the post-travel was long and gradual enough that even an aggressive operator like me wouldn't normally bottom out. IBM beam springs got part of the way by using two springs (one of them two-piece). Another spring or two, or some nonlinear springs, could probably do better.
flavio81 9y ago
I owned and used a Selectric typewriter for many years and I did not like the key feel. Basically, too light!!
type0 9y ago
Here is a review of the beam springs and some of it's problems: https://www.youtube.com/watch?v=hNRH1ULmbNA https://www.youtube.com/watch?v=hNRH1ULmbNA
- kps 9y ago
  The big problem there, slow speed, is not inherent to the technology but stems from the replacement (USB) interface. Scanning the capacitive matrix of these keyboards with a commodity microcontroller is an amazing achievement, but it only just barely works.

by kps 9y ago

efm 9y ago

What mechanism did the Selectric use?

dwringer 9y ago
"When the typist presses a key, a pawl on the key lever depresses a matching metal bar (interposer) for that key. The interposer, which is oriented front to back in the machine, has one or more short projections (lugs) protruding from its bottom edge. Each interposer has a unique combination of lugs, corresponding to the binary code for the desired character. Each interposer also has a tab that slots in between loose steel balls in a race, the size of balls and race selected precisely to leave a total gap barely larger than the width of the interposer tab, such that only one interposer tab can fit in the free space and thus only one letter can be selected at a time." [1][2] Not exactly comparable to the one on a modern PC, I guess. [1] https://en.wikipedia.org/wiki/IBM_Selectric_typewriter#Selectric_mechanism https://en.wikipedia.org/wiki/IBM_Selectric_typewriter#Selec... [2] https://www.youtube.com/watch?v=uTjxwVfx8GA https://www.youtube.com/watch?v=uTjxwVfx8GA
- kps 9y ago
  The Selectric feel was particularly good in a few ways: - it had a very light pre-pre-travel of a millimetre or so, providing distinct touching-but-not-pressing feedback; - the force drop at the tactile snap point was so high it felt like the keyboard was actively trying to help you type; - the post-travel was long and gradual enough that even an aggressive operator like me wouldn't normally bottom out. IBM beam springs got part of the way by using two springs (one of them two-piece). Another spring or two, or some nonlinear springs, could probably do better.

flavio81 9y ago

I owned and used a Selectric typewriter for many years and I did not like the key feel. Basically, too light!!

type0 9y ago

Here is a review of the beam springs and some of it's problems: https://www.youtube.com/watch?v=hNRH1ULmbNA https://www.youtube.com/watch?v=hNRH1ULmbNA

kps 9y ago
The big problem there, slow speed, is not inherent to the technology but stems from the replacement (USB) interface. Scanning the capacitive matrix of these keyboards with a commodity microcontroller is an amazing achievement, but it only just barely works.