'Vaporfly' switches - I want'em!

[Keybug]

Been wondering if this type of technology couldn't be applied to keyboard switches as well. Any ideas?

"Nike Vaporfly shoes make runners faster, but they're controversial - Business Insider" https://www.businessinsider.de/internat ... ?r=US&IR=T

[gipetto]

the selling point is that it increases running efficiency. I am unsure how that could improve a switch. if you are talking about replacing a membrane with the foam the vaporfly uses the difference would be negligible. rubber done keybs are already quite easy to actuate.

[Keybug]

Well, this is the key passage:

The Nike Vaporfly sole helps runners lose less energy per step

Jake Riley, an American runner who finished ninth in the 2019 Chicago marathon, has said the Nike Vaporfly 4% shoes feel like „running on trampolines.“

The secret is in the sole, which is designed to help runners get the most forward push for each stride — or, in Burns‘ words, to run faster for the same „energy expenditure.“ The soles consist of a foam layer and carbon-fiber plate fused together.

In addition to protecting our legs from the impact of striking the ground, running shoes store and release energy to propel us forward. The midsole acts like a spring, compressing when a runner lands, storing the energy from that foot strike, and expanding again to return that stored energy into the ground to push them forward.

Not all of that stored energy gets returned with each footfall, though — some dissipates as heat. But the Vaporfly’s design minimizes that amount of lost energy, giving the runner more bang for the buck.

Traditional running shoes generally use ethylene vinyl-acetate foam, which returns about 65% of the energy you put into it, according to Burns. The Vaporfly, by contrast, uses a new type of foam called Pebax, which is about 87% efficient. (The patent is owned by a French chemical company called Arkema.) The addition of the carbon-fiber plate helps the Pebax foam compress and expand quickly.

„Otherwise it would be like a marshmallow,“ Burns said.

Kyle Barnes, a movement scientist who authored a study about the Vaporfly shoes in February, told Business Insider that the carbon-fiber plate is curved under the front of the shoes, which also makes a big difference. That curvature, he said, helps quickly rock a runner from their heels to their toes as they land and push off again.

As key movement is only one-dimensional as opposed to the two dimensions of foot movement in running, some aspects of the 'Vaporfly' clearly don't apply, for example what is covered in the last paragraph from the quoted passage (on forward movement).

However, I think the rest of what is said here quite clearly applies to bottoming out on keypresses. So a pertinent question would be, how much energy is lost when bottoming out and might certain materials (e. g. Pebax) reduce energy loss and result in faster and less exhausting typing.

Trampoline mods have been done in the community and O-rings under keycaps have a pretty similar effect. If we had Pebax O-rings, maybe we could all type 4% faster and / or longer? I don't think 4% would be 'negligible':

Over 26.2 miles, 4% more efficiency is a lot

[micmil]

Let's see here...
Cherry MX key travel is ~4mm.
4mm == 2.48548e-6 miles.
26 / 2.48548e-6 = 10460756.0713

So 4% efficiency over 10 million key presses which you'd never reach because have you ever done the math on how long it takes to get to 10 million key presses? Yeah I know that has nothing to do with anything but it's no less ridiculous than worrying about the efficiency loss from bottoming out key presses when you could simply LEARN TO TYPE BETTER and not do that.

Some more piss taking...

4% efficiency at 100 WPM means 104WPM. An extra 240 words per hour. Roughly half a page. At that rate The Winds of Winter may be finished some time shortly before the Light Zone is overtaken by the Mantrid Drones.

[ddrfraser1]

In that case, I’ll take a sharkskin keyboard to make it more hydrodynamic.

[xxhellfirexx]

That will likely not translate well to keyboard switches unless you want tall switch modules with 300 gram actuation force. The foam is really dense to support your body weight. And if you are mushing the foam hard enough to get rebound, you are better off typing on a membrane keyboard as you will have to bottom out anyway.

[Keybug]

1. I knew I shouldn't have tried to enlighten this haven of keyboard luddites and traditionalists with my brilliant idea, should have just gone straight to reddit!
2. The argument that minor improvements in typing feel and speed don't matter is pretty rich on a forum where many spend100s of $$ to get that beamspring / blue Alps feel...
3. With the proper adjustments to the foam's density, height etc, who's to say that it might not actually be more effective for typing than for running?
4. Please stop it with the 'bottoming out is bad' rap! The idea of actively decelerating your fingers in mid fall without feedback at the exact same position for every keypress and expecting to reach similar speeds, error rates and ergonomics as with bottoming out is just preposterous. Learn to love your bottom (!), just make sure it's agreeably soft. Hooray for soft bottoms! (Not so much for mushy ones, though - that's where the high-tech foam comes in, I suppose...)

[Bjerrk]

From a physics point of view, the effect you're talking about would be very easy to achieve.

Good old Hookean springs, which have a linear stress-strain relation would do this just fine. They store energy due to a compression displacement x as E=(1/2)kx^2, with k the spring constant.

So, yes, if you add a stiff spring that kicks in shortly before bottoming out, ensuring you reach the actual bottom-out with very low velocity (if at all), then you can recover essentially all the energy. This could also be obtained with a suitably nonlinear return force element.

So, yes. Not a problem. Whether it would be an enjoyable typing experience is another matter. Cherry MX Clears are somewhat in that ballpark, with their very high bottom-out force, but could of course be improved upon.

Sincerely, a physicist.

[Keybug]

Thanks for your input.

I would posit that for an ideal typing experience there should be an element either inside or outside (like a high-tech O-ring) the switch itself hat while signalling clearly to the finger that the end of the motion has been reached, is designed to 1. return as much of the energy expended at this point back into the upward motion of the finger and 2. create the kind of feel that seems most pleasant to the user, i. e. neither too hard nor too mushy. Trying to have a single element take care of all of that (think MX clear springs) is bound to create sub-par results.

While I realize that some switch designs (e. g. Topre) have sort of done this as a by-product, it seems to be mostly ignored in present-day switch designs and optimized materials have hardly been considered for this aspect of the keystroke. For the MX platform, it's either you use standard O-rings or you don't. Or you use springs with force curves to soften the bottom-out or you don't. [edit:] Just realize there are also 'landing pads', but not sure what kinds of materials they're made of.

Also, I've been wondering whether switch designs that were to actually *add* energy into the upstroke, e. g. by a magnetic reversal or somesuch, might make typing faster / more comfortable...

[micmil]

1. I knew I shouldn't have tried to enlighten this haven of keyboard luddites and traditionalists with my brilliant idea, should have just gone straight to reddit!
2. The argument that minor improvements in typing feel and speed don't matter is pretty rich coming from people spending 100s of $$ to get that beamspring / blue Alps feel...
3. With the proper adjustments to the foam's density, height etc, who's to say that it might not actually be more effective for typing than for running?
4. Please stop it with the 'bottoming out is bad' rap! The idea of actively decelerating your fingers in mid fall without feedback at the exact same position for every keypress and expecting to reach similar speeds, error rates and ergonomics as with bottoming out is just preposterous. Learn to love your bottom (!), just make sure it's agreeably soft. Hooray for soft bottoms! (Not so much for mushy ones, though - that's where the high-tech foam comes in, I suppose...)

1. This is some grade-A copypasta beauty. Thank you for enriching my life with this bit of self-aggrandizing horseshittery.
2. Literally nobody has made that argument.
3. Grams of force over the course of 4mm of key travel vs 100+ pounds of force over 26 miles of travel. Stop comparing these things.
4. You seem to be arguing something nobody is talking about.

Look, you just seem like you want to be mad because nobody thinks your oh-so-brilliant idea, which amounts to how foam-based switches already work, is any good. Yes, please, go to reddit. Don't be surprised when nobody gives a damn over there either.

[micmil]

1. I knew I shouldn't have tried to enlighten this haven of keyboard luddites and traditionalists with my brilliant idea, should have just gone straight to reddit!
2. The argument that minor improvements in typing feel and speed don't matter is pretty rich coming from people spending 100s of $$ to get that beamspring / blue Alps feel...
3. With the proper adjustments to the foam's density, height etc, who's to say that it might not actually be more effective for typing than for running?
4. Please stop it with the 'bottoming out is bad' rap! The idea of actively decelerating your fingers in mid fall without feedback at the exact same position for every keypress and expecting to reach similar speeds, error rates and ergonomics as with bottoming out is just preposterous. Learn to love your bottom (!), just make sure it's agreeably soft. Hooray for soft bottoms! (Not so much for mushy ones, though - that's where the high-tech foam comes in, I suppose...)

1. This is some grade-A copypasta beauty. Thank you for enriching my life with this bit of self-aggrandizing horseshittery.
2. Literally nobody has made that argument.
3. Grams of force over the course of 4mm of key travel vs 100+ pounds of force over 26 miles of travel. Stop comparing these things.
4. You seem to be arguing something nobody is talking about.

Look, you just seem like you want to be mad because nobody thinks your oh-so-brilliant idea, which amounts to how foam-based switches already work, is any good. Yes, please, go to reddit. I'm sure many of us will see you over there. Don't be surprised when nobody gives a damn over there either.

[Keybug]

This is fun! I should do more trolling in the future!

1. This is some grade-A copypasta beauty. Thank you for enriching my life with this bit of self-aggrandizing horseshittery.

You're not much one for subtlety and irony then?

2. Literally nobody has made the argument.

that that minor improvements in typing feel and speed don't matter.
Hmm, I quote:

it's no less ridiculous than worrying about the efficiency loss from bottoming out key presses

3. Grams of force over the course of 4mm of key travel vs 100+ pounds of force over 26 miles of travel. Stop comparing these things.

I wasn't, as - indeed - it wouldn't make any sense. What I would like to compare is one step of a runner vs. a single keypress - or a very long typing session to a marathon run.

4. You seem to be arguing something nobody is talking about

when discussing bottoming out.
Hm, again, I quote:

you could simply LEARN TO TYPE BETTER and not

bottom out.

You want to be mad because nobody thinks your oh-so-brilliant idea, which amounts to how foam-based switches already work, is any good.

Well, no and yes - but with 'state-of-the art' foam.

Yes, please, go to reddit. Don't be surprised when nobody gives a damn over there either.

Wow, something I said must have really gotten to you. Peace!

This thread might actually turn into something useful if members were to voice their opinion on which switch types have so far been most successful at improving the bottoming-out experience and how relevant they think it is to overall switch feel and whether it is being addressed sufficiently by current switch designs / variations (think Hako switches etc.).

[Bjerrk]

Absolutely. I don't know why micmil insists on all that unproductive complaining. To each his own.

As for the actual question: you may be right that the effect would be easier to obtain with more than a single return force element (which is also why I mentioned having a stiff spring that kicks in towards the bottom of the keypress). However, I find that, in thinking of these kinds of things, it is often useful to abstract away such practical details initially.

The question is really: Assuming a conservative return force (meaning one that doesn't dissipate the mechanical energy), what force curve would you like?

I'd say that you want one that rises quite sharply over the last few tenths of a millimeter (before bottom-out). This is where Cherry MX Clears fall short: The force rises to a high level pre-bottom-out, bot not particularly sharply. (Which of course makes sense, since a single Hookean spring provides the return force during the entire keytravel).

[Keybug]

Yeah, of course, a second spring might work even better than something involving foam, though it would mean a complete switch redesign as opposed to just sticking some kind of foam in or around the switch somwhere . I have a feeling that a leaf spring might be particularly well suited to the task, but maybe you have more insight into the specific attributes of the different types of springs.

Just like you say, there should be a very steep rise of the force curve at the very end to still give the nervous system the 'you've hit bottom' feedback while making it a bit easier on the finger joints and at the same time recycling as much of the energy back into the upwards movement as opposed to hammering it down into the desk.

[micmil]

This is fun! I should do more trolling in the future!

Sure. "Trolling."

I'd say that you want one that rises quite sharply over the last few tenths of a millimeter (before bottom-out).

Haaaaaave you met rubber domes? Or foam. Neither will be fully solid, they just have a REALLY solid rise in the force curve. Even if you soften this curve all you're effectively doing is aping "mushy" key feel.

Whatever the case there has to be some non-linear springs of the right size for some nutcase switch modder to jump on. It would be interesting just for the shiggles but what I'm expecting is that it would be quite mushy.

[micmil]

Just like you say, there should be a very steep rise of the force curve at the very end to still give the nervous system the 'you've hit bottom' feedback while making it a bit easier on the finger joints and at the same time recycling as much of the energy back into the upwards movement as opposed to hammering it down into the desk.

AKA: Tactility.

[Bjerrk]

Sure. "Trolling."

I'd say that you want one that rises quite sharply over the last few tenths of a millimeter (before bottom-out).

Haaaaaave you met rubber domes? Or foam. Neither will be fully solid, they just have a REALLY solid rise in the force curve. Even if you soften this curve all you're effectively doing is aping "mushy" key feel.

Hi micmil,
I see you're staying true to your somewhat derisive style. Good for you

Did you catch on to the part about dissipation? I think it is quite essential do avoid the "dead", mushy feel.

[Keybug]

Well, the idea is that it should be bouncy rather than mushy. There is a difference...

Tactility isn't what I'm talking about as it is supposed to signal actuation rather than the physical end of the movement so it is usually placed far above the switch's bottom.

[micmil]

You want something that will increase the force required at the bottom-out point while providing an upward assist to redirect the force and conserve energy.

This is called a trampoline. A non-linear spring will give you a similar effect. But you're going to run into problems. The easier one is which force will your muscle memory adjust to? Are you going to start extra-smashing the keys because you're used to the feel of bottoming out, or are you going to become super-feathery at which point you're losing all benefit from almost bottoming out and getting that energy conservation effect?

To get maximum conservation of energy each and every key would have to be tailored to the individual FINGER, not in a broad way like Realforce or Ergoforce but each key weighted individually for both initial and increased force. If you want to get absolutely batshit, at any rate.

As I already stated, it would be interesting to see how it would work out (my conjecture: Mushville, Population: That Keyboard) and all we need is some nutter with the right size non-linear springs to get it done.

[Keybug]

Yes, a non-linear spring would do that, except non-linear springs don't exist according to this very interesting bit of keyboard science that I just managed to dig up. This supports Bjerrk's and my contention above that, really, a second element (spring, foam or whatever) is needed to properly manage bottoming-out in a switch, controlling the disspation / reversal of energy etc. If MX clear / Hako switches did this really well, I bet they would have become much more popular...

Correction: Progressive springs do exist, but are apparently sold exclusivley by Spirit Designs are not available in any of the major stock springs! See this interesting comparison of different spring variations here.

Will have to go and buy some of those progressive springs now!

[XMIT]

Umm. Conical springs are non-linear. You could make a cylindrical spring non-linear by varying the distance between coils or the thickness of the wire.

Random link from Google discussing software for conical spring design:

https://www.hexagon.de/fed5_e.htm

[Thorogrimm]

Well, the idea is that it should be bouncy rather than mushy. There is a difference...

Tactility isn't what I'm talking about as it is supposed to signal actuation rather than the physical end of the movement so it is usually placed far above the switch's bottom.

It could potentially be similar to hall effect

[micmil]

Yes, a non-linear spring would do that, except non-linear springs don't exist according to this very interesting bit of keyboard science that I just managed to dig up. This supports Bjerrk's and my contention above that, really, a second element (spring, foam or whatever) is needed to properly manage bottoming-out in a switch, controlling the disspation / reversal of energy etc. If MX clear / Hako switches did this really well, I bet they would have become much more popular...

Correction: Progressive springs do exist, but are apparently sold exclusivley by Spirit Designs are not available in any of the major stock springs! See this interesting comparison of different spring variations here.

Will have to go and buy some of those progressive springs now!

Using r/mechanicalkeyboards as a reference is a bad idea. The insularity is on part with Goldeneye speedrunners, who didn't even know that looking at walls increases framerate for 20 years after everyone already knew that.

[Keybug]

Thanks for chiming in!

It would seem then that while concial springs could approximate what I want, the MX platform isn't designed to accomodate them. Spirit's progressive springs therefore achieve progression with a fixed diameter but increasing distance between coils; not sure what the technical term for that type of spring is. See here:



While the complex and progressive springs on offer are interesting and I will certainly try them out, I still believe that a second kind of mechanism specifically aimed at regulating the bottom-out would be far superior as the the feel of the key travel could be kept entirely separate from that of the bottom-out. As Thorogrimm suggests, this mechanism could also be magnetic in nature. O-rings are a very basic but certainly not ideal example of such a mechanism.

Master question for those in the know: Do any vintage switches have components designed specifically to take care of the bottoming-out process? I guess a contact leaf often doubles as a component regulating bottom-out feel.