Spring weights

[jacopods]

It seems to me that most of the (even custom) cherry mx spring weights are distributed quite uniformly between 35g and 67g (actuation). Then there is a gap to 80g and larger gaps down the road. Anybody has suggestions for weight between 67 and 80? These should be between clears and grays for the cherry tactile stem as far as I understand.

[davkol]

There are two important properties: spring rate and pre-load. (Assuming uniform size.) Unfortunately, the market seems to ignore this crucial fact, and uses a single reference point (randomly picked between actuation point and full compression).

I believe the relevant springs are 80g (MX Black), 85g (MX Clear: cushioned-landing feel), 68g ("softer" MX Black) and 78g ("softer" MX Clear), dunno about "stiffer" ones, at least from sprit (leaving aside his business history).

[Muirium]

Springs are only part of the story. The switch mechanism itself plays an effect. MX Clear’s tactile bump, for instance, is a particularly gnarly bit of plastic slider action.



I’d like to compare springs directly, outside of the various non-linear switches they work inside. Pity there’s at least two different scales out there when describing them. Simple springs (like in MX and its clones) should have a simple linear response, following Hooke’s Law. They should have a single constant coefficient we can use to define them, irrespective of different switches’ different events.

The complexity strikes when you take a simple spring and put it inside different switch designs. The spring is still being linear, but the switch overlays its own effects.

Oh, and I said “simple springs” because I don’t understand the variably wound springs inside Space Invaders:



Those springs could well have complex force curves. But people invariably only ever talk about MX, so these remain an interesting irrelevance.

[Hypersphere]

As Mu has pointed out, it would be great if someone would bother to determine the value of "k" in Hooke's law, F = kx, where F is force, x = displacement distance, and k = a constant characteristic of the spring. Then, at least for simple springs we would have a number that could be used for comparison.

As it stands, we have at least two scales of comparison commonly used for keyboard springs. One based on actuation and the other on "bottoming out", which would be full compression if the spring were indeed fully compressed in the switch when the switch bottoms out.

Interesting aside: Mu, thanks for showing us the compound springs inside "Space Invader" switches. Although I have had Space Invader keyboards and taken apart some of the switches, I've never seen the switches, because upon taking the switch apart, the spring flew off into hyperspace, where it apparently lives with unmatched socks and other things irretrievably lost.

Compound switches also obey Hooke's law (within limits imposed by the material used to make the spring). If two component springs are connected in parallel, the combined Hooke's constant, ks = k1 + k2. If the two component springs are connected in series, the combined Hooke's constant is 1/ks = 1/k1 + 1/k2 or ks = k1k2/(k1+k2).

[Muirium]

Those space invader springs are compounds, consisting of a single wire with variable wrapping along its length. I wouldn’t rush to simplify them for modelling’s sake. But as I pointed out when I introduced them (to ward off helpful pedants!): whenever people talk of springs, they mean MX and clones. Much as I myself prefer NMBs!

[jacopods]

Yes and yes, switches are complicated beasts and different stems will have different actuation points and thus the "actuation" figure is inherently inaccurate. The way that I think about these numbers is they just give an "arbitrary scale".

I am looking for springs which fit in the gap between 67 and 80. It appears that they are not easily available and I am asking whether you guys know how to get some

[swampangel]

I am looking for springs which fit in the gap between 67 and 80. It appears that they are not easily available and I am asking whether you guys know how to get some

There are springs from sprit available in 72g and 78g from https://mechanicalkeyboards.com/shop/in ... list&c=339

@davkol mentioned them above -- I don't know what the "business history" referred to is about (since I live comfortably over in alps-land)

[davkol]

sprit has a history of scamming people. Buying his springs from another vendor should be safer but still gives him money.

[swampangel]

sprit has a history of scamming people. Buying his springs from another vendor should be safer but still gives him money.

I googled and found some of the long standing group buy grievances over on GH.

[jacopods]

I am looking for springs which fit in the gap between 67 and 80. It appears that they are not easily available and I am asking whether you guys know how to get some

There are springs from sprit available in 72g and 78g from https://mechanicalkeyboards.com/shop/in ... list&c=339

@davkol mentioned them above -- I don't know what the "business history" referred to is about (since I live comfortably over in alps-land)

The listing there is for "bottom out weights", so those would still be lighter than clears, I guess.

[Hypersphere]

Some time ago, I ordered a set of springs directly from Spirit. I received my order with no problems.

Currently, it appears that the widest selection of spring weights is available from Originative.