How bad would be the gap in a IBM keystem-to-MX adapter?

[TacticalCoder]

I know that the spring is inside the "skirt" of the keystem, but looking at one of my keystem I noticed that there was quite some vertical room before the spring.

Couldn't you make a keystem for a Model M looking like this, on which you'd then plug Cherry MX switches without having too big of a gap?

keyboardKeyStemToCherryMXswitch.jpg (26.5 KiB) Viewed 3540 times

How "tall" does the part of the stem receiving the MX switch need to be?

I ask because I'd love to replace the black M13 keys on my industrial M with real double-shots keys

(I'd probably buy 5 full sets of keystems on which I could plug MX caps and maybe more...)

[Compgeke]

One thing to keep in mind with this: You'll need to make custom adapters for each row. MX keys are designed to make a curve on a flat board whereas Buckling Springs are designed to make a curve on a curved board.

[TacticalCoder]

One thing to keep in mind with this: You'll need to make custom adapters for each row. MX keys are designed to make a curve on a flat board whereas Buckling Springs are designed to make a curve on a curved board.

yup I know but first I'd like to know if it's doable or not. Starting with the function keys row could be an idea: only 1x keys there and there are less "problems" with the curve thinggy.

Basically I'm wondering if it's doable or not: I know Ripster did mod a few keystem to put MX switch on Model M and Tsangan got one of these...

But then I've read that due to the spring it's problematic. Now the idea would be to model a complete keystem (without the keycap) that would replace the original keystem. Its flat surface would be lower than on a real Model M keystem (because despite the spring I'm pretty sure there's some room in there, as seen on the drawing from the patent) and there would be a cylinder with the MX fixation.

The question is: would it work? And also: who can build something close enough to the original keystem so that it would work flawlessly? (I take it a 3D printer ain't gonna be precise enough and even shapeways I'm not sure but maybe it could be enough to at least see if the idea could work or not)

That's why I'm asking here...

I don't have the 3D modelling skills to do it but I'd be willing to pledge some bucks for such a project

[TacticalCoder]

It could be lowered even more than what I showed in the first picture. And that would be without going higher than the original one piece keystem. Now I know that MX keycaps are "taller" then the keycap from the Model M (where it's just "flat surface on flat surface) but still: maybe that would already be more than enough.

Which is why I'm asking how much would be needed vertically to hold a MX keycap.

I've got quite some Model keystems here and a few crappy MX keys (not DS ones) so I may give it a try just for fun.

(I already managed to "convert" a regular 'G' and 'H' keys to "M13" 'G' and 'H' keys, with room for the trackpad )

I'm really curious about this...

3keyboardKeyStemToCherryMXswitch3.jpg (39.94 KiB) Viewed 3511 times

[Halvar]

The inner stems on MX keycaps are usually much longer, and they need to be because they "dive" down into the switch case when the key is pressed (sorry for my bad English).

The vertical distance between the lower end of the keycap stem and the plane of the cap bottom is less than 0.5 mm on the MX keycaps I've seen.

[Muirium]

They do indeed dive right into the MX switch body. Unmodified MX caps are always going to be extra tall on IBM because their stems occupy part of the same space where the buckling spring lives.

Topre might be an easier target for MX adapters because of its flat backplane and recessed mounts:
http://deskthority.net/workshop-f7/cher ... t6596.html

[M'er Forever]

[Account and posts deleted on request]

[kbdfr]

The inner stems on MX keycaps are usually much longer, and they need to be because they "dive" down into the switch case when the key is pressed…

Actually they do not need to. If you shorten both the "cross" part of the switch and the stem of the keycap, the result is to lower the position of the keycap without any negative impact on activation as long as the remaining length of the cross/stem part is about 2mm (=required activation travel of MX switch). This length could be even less on the proposed adapter since the buckling spring activation system remains unchanged.

So the "new" adapter could have a shorter cross stem than MX switches, but of course it would probably still be necessary to shorten the inner stems of all MX keycaps used on such a board.
However, this wouldn't have to be precision work as long as the inner stem of the cap is i) not longer than the stem of the adapter and ii) long enough to allow the cap to seat on the stem without popping off.

[7bit]

I suggest to exclusively use row 1 DCS-family or row 3 SA-family key caps, because the keyboard itself is already curved.

I'm quite sure SP can make these without key mounts, we just need IBM stems to be glued into them.

Or maybe SP can make a BS-stem for the sphericals?

[warty]

You'd think SP would be able to simply make the cap part of the 2 part BS key caps. But I don't know anything about turning petroleum into finger toys.

[M'er Forever]

[Account and posts deleted on request]

[daedalus]

The Alps Buckling spring switch used a slider over the buckling spring.