Cherry MX key caps on IBM Model M

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snuci
Vintage computer guy

04 Mar 2017, 23:36

This was the true reason I was playing around with switch adapters. After being bestowed by two honours in January, I had this project in mind but wasn't sure this would work. For the record, I won a DTA6 Wingnut for Best Vintage Keyboard or Cache with an industrial Model M rescue at a Ford plant. The second honour was by our very own Daniel Beardsmore who adorned my personal Wiki page with a Wiki Stars badge.

I wanted to have the Wingnut on my best keyboard from the Model M find so I worked on an adapter because the Wingnut has Cherry MX mount. Well, this was the best I can do. Unfortunately, this will NOT work as the key cap is too high and it cannot be lowered anymore. The adapter needs some work to prevent it from spinning (it's a little too narrow) but there is no use as you cannot put Cherry MX key caps on a Model M and make it work. Mind you, the Wingnut is still clicky just like any other Model M key cap :) Of note, the key cap does travel inside the Model M barrel but it's still too tall. You would need shorter springs and that would mess up the Model M completely.

Here are some pics:
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User avatar
Techno Trousers
100,000,000 actuations

04 Mar 2017, 23:51

you cannot put Cherry MX key caps on a Model M and make it work.
Yikes, that doesn't bode well for future MF projects. Is that true of "regular" Cherry type caps as well?

User avatar
Daniel Beardsmore

04 Mar 2017, 23:56

Now you see the problem with making discrete buckling spring modules that take Cherry keycaps. IBM sliders (and integrated mount keycaps) have to be the shape they are to keep the height down.

While you could resolve the aesthetics with a longer keycap skirt, it would make more sense to simply make the correct keycaps in first place.

With that said, the mounting shaft inside the keycap is taller than the keystem, so you could put Cherry keycaps onto some grinder or what not and remove some of the mounting shaft so that it sits lower down. Whether the Wingnuts are adaptable in this way, I don't know.

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fohat
Elder Messenger

04 Mar 2017, 23:59

Is it close? Would topping the barrel by a couple of mm make it work? Just asking.

User avatar
snuci
Vintage computer guy

05 Mar 2017, 00:14

Gringind might work but it will jeopardize the stability of the MX key cap. What I've done is trimmed down the Model M key stem down to the red line and put the MX cruciform on top. Any shorter and I hit the spring pin inside the key stem (what is inside the Model M key cap). It's approximately cut at the red line beyond the normal length. There's not much more room to play. The Model M key cp skirt is pretty long when you look at it and it is very thin on top.

Note that this illustration has the key cap depressed. My picture above is not depressed.
ModelMBucklingSpring.jpg
ModelMBucklingSpring.jpg (29.38 KiB) Viewed 1992 times

User avatar
Daniel Beardsmore

05 Mar 2017, 01:57

Bad idea.png
Probably a bad idea for a reason I've not come up with yet …
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Maybe Cherry M8 keycaps would work better …

User avatar
snuci
Vintage computer guy

05 Mar 2017, 15:13

The current design is pretty tight as it is. I printed an MX key cap and cut it away so you can see the normal (resting) and depressed state. I do have a millimeter or two to play with so I'll toy around with it a little later today. I don't think the Cherry key cap type matters as the underside key cap stem goes into the Model M barrel as it is.
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Resting state
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IMG_1964.JPG
Depressed state
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User avatar
lot_lizard

09 Mar 2017, 17:16

I would have been happy to share what I have for you to build on Snucci (sure Matt3o would have done the same). PM me with the file format you are using, and I will send over my design. You might need to adjust slightly based on the printer you are using to get the movement right. It took me quite a while to get the design to turn over into actual print dimensions since these are so small (so be warned... there are "tolerance" comments everywhere).

For what it is worth, my distance between the base of the MX mount floor and ceiling of the spring is only .5mm, and you are able to lower the ceiling (I can't remember the dimensions... been a while) and not impact the functionality of the switch in any noticeable way on a stock M spring. Obviously if the spring is shortened and thinned somewhat, the ceiling could be lowered even further. The issue I had on height was more in regardless to the ceiling of the MX mount bottoming out on the BS barrel top that I believe Fohat was mentioning.

There are multiple problems with trying to do this on a complete board if you wanted mixed MX and BS caps. As you say, the skirts are NO where close to the BS ones. On a full board with universal caps, compensations can be made though (future designs). I currently have the wingnut on a modified design that looks really nice, BUT I am using on an F switch where the barrel is unique compared to its brothers (ground down) and the spring is our from our lighter tension experiment. Works quite nicely though... but I don't think you would want to grind down your M barrel since it is an integrated frame.

Moral, I have something that works with an F if you want it, but with an M... I'm not sure you do. As Beardsmore pointed out, we really have to make something unique altogether to get this to actually be desirable if we want MX and BS to like each other.

User avatar
snuci
Vintage computer guy

09 Mar 2017, 18:41

Sorry lot_lizard. I didn't know someone else had worked on this already. From Techno Trousers response, I guess this was discussed in the mammoth MF thread? No disrespect but I gave up on trying to keep track of what was going on in that thread long ago.

I tried a couple of other things with this design but gave up for now. I have an issue with the key stem spinning and needed to make it slightly bigger. In any case, I couldn't make it any shorter for this to work with normal MX key caps without a noticeable increase in length.

Never really though about a Model F. I figured since Model M's are plentiful, it would have been interesting to change up the key caps easily. I won't replace springs or grind down barrels so I'm fine at, at least, trying something. If you are already doing something with the Model F then I'll PM you just to try it.

Thanks.

User avatar
lot_lizard

09 Mar 2017, 19:18

snuci wrote: From Techno Trousers response, I guess this was discussed in the mammoth MF thread? No disrespect but I gave up on trying to keep track of what was going on in that thread long ago.
If I came across the wrong way, apologies on my part... I love that someone actually bright is fighting this fight too. Shows there is need and we all appreciate that others are taking stabs at it.


That MF thread is ridiculous in length, I agree. I am not sure if/how to split it up though. We have a following of "loyals to the cause" that make AWESOME posts that wouldn't be seen by those that need to, but unless someone is really actively following it, the thread is impossible to keep up with. The good/bad of online social fluff. Our problem is that we are trying to accomplish too much at too quick of a pace I think (blame OCD).

The real hiccup that brought us to the a GRINDING halt on the adapter was the Capslock key. It just can't work if we are wanting a way to get a uniform board of MX on BS (regardless of profile height). All other keys could be compensated for with adapters and modified springs, but that one... Why IBM did you offset that stem?!? No really... WHY?!?

We decided to wait until could make a full switch and board layout (MF^2) that at least components of the switch could act as forward and backward compatible. Unfortunately... the Cherry adapter wouldn't be one. If we do it right going forward, we can get away with 2 molds. Right now, assuming Capslock worked, it would require 7 for a 101+ key. The crappy reality of this being a break-even hobby (little funding).

Sarreq Teryx

20 Oct 2017, 06:47

If someone is selling these, I'm certainly looking to buy. I don't mind the caps being taller than normal.

Red_October

12 Jan 2019, 03:16

Has there been any progress on these? I've recently picked up a couple of sets of Spherical keycaps but of course they are MX mount, and as of yet nothing I have met with that is MX-mount is in the same rarefied air as my Model F 122-key...

User avatar
PlacaFromHell

27 Jan 2019, 08:57

Guys, I have a question. Will this work for a custom keyboard with a non curved plate? I want to end all my other projects first, but my idea is have a "beamspring looking" model F with cool sphericals.

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