Idea: 3D printing of IBM Buckling Spring stem for MX caps

[warty]

I've been trying to interest Unicomp in a black/white key caps set for BS keyboards, but they stopped responding

So, on to plan B: do a 3D printing of a BS-compatible stem, with a + stem that can take a Cherry MX keycap. In theory, letting you use your cherry caps with your Model M etc.

So, imagine something like this:
https://www.shapeways.com/model/1180046 ... terialId=6

But with the top cut off and just being a + stem.

$3 a stem is going to be pricey.

What do you guys think? Is it do-able? It seems like it should be... The 3D printed part never shows up, so you don't have to worry about finish. If we got the plus part of the stem tight enough, there shouldn't be any significant extra wobble. I'm a little worried the plastic won't be hard enough, but I've never done anything with 3D printing so don't know what the plastic is like.

[7bit]

It might be cheaper to let SP make tools for sphericals that fit on top of a BS-stem.

We only need 1 and 1.5 units for the beginning, except that we would need space bars from Unicomp in matching color ...

[Game Theory]

Seems like a great project. Are you nfc1 at shapeways? If not any idea who nfc1 is? Many IBM Model parts
https://www.shapeways.com/shops/nfc

[Game Theory]

It might be cheaper to let SP make tools for sphericals that fit on top of a BS-stem. ...

But then would BS specific caps need to be ordered? -> Lower Qty -> Higher Price per Cap

[7bit]

OK, indeed we would need only one king of stem. Still problematic for the space bar. The only solution that comes to my mind is drilling away the MX-stems and glue special IBM stems into it at the correct positions.

If this turns into na grup buy and if it really works, I'd be interested in at least 400 stems.

I already have the all-row-3 key caps which are most useful on the curved Model M.

[Muirium]

I like what you're thinking here. Anything that opens up the world of MX caps for IBM. A couple of issues come to mind though:

1. All that extra height. These adapters will mount the caps quite a bit higher up. Every millimetre counts for key feel *and* even more for the second thing.

2. Curved backplane (IBM) versus flat (MX). IBM caps are uniform across all rows. Some MX caps are too (DSA profile comes to mind) but most aren't. I wonder if the curve of an IBM board isn't too steep to give these tall (see number 1) caps enough space between each other to sit.

But well worth investigating, for sure. As IBM made their caps for interchangeability in the first place. We may be able to exploit this.

[7bit]

I don't recommend to put regular Cherry key caps on, except you make row-specific adapters.

The cool thing would be to have thick sphericals, so typing comes closer to real Selectric feel.

[warty]

I'm not sure how to test the height. People have dremeled out cherry caps and put them on cut-off IBM stems. It looks like they are dremeling out the entire cap stem. I think we'd get pretty close to that though.

The plate curve is indeed going to be a bit of an issue. I think 7Bit is right: it's either DSA or we pick a specific row profile and order it, which makes it pretty worthless for anyone NOT putting it on a BS keyboard.

So given that, does it make more sense to ask SP to make BS cap (tops)? I didn't realize that was an option for them. Would it constrain the shape of caps they could make? SPH not doable maybe, but DSA like ones possible? I suspect if SP could make the caps, the experience would be better: probably less wobble, and wouldn't have to worry about some 3D printed stem degrading over time or something. On the other hand, you lose the flexibility of (potentially) re-using all the many kinds of cherry caps out there.

I'd buy at least 400 too.

[warty]

ah, row-specific stem adapters. I don't see why it wouldn't be possible. It would make it harder to keep track of your stems, and how many you want of each kind, but I dunno, that might work.

[tlt]

$3 a stem is going to be pricey.

Put all the stems you need in one 3D model and connect them with tiny bridges that later can be cut of to get a better price on 3D printing. I think 3D printing is a good option for prototyping this.

[Compgeke]

There are a couple problems I can think of with 3D printing these right away:

1.) You would need to design them vertical, with the cherry mount down. This here is to make sure that you get a somewhat round side on the IBM side and to make sure overhang doesn't kill the design.
2.) Making sure that your measurements are exactly correct, or this won't work right.

Anyways, if anyone comes up with a design I can 3D print a couple keys worth to test as I have access to a 3D printer, I just can't print what would be required for an entire keyboard.

[Muirium]

Mr. Interface is working on the opposite adapter, and has prototyped his design recently:

We discussed it a bit in the thread. Cherry stems to IBM caps is an easier adapter to pull off, not least because of IBM's modular design.

Row profiles and long mounts make MX caps a pain to adapt. Membranes and barrel plates make buckling spring switches a pain to make custom keyboards from. Each of them gets it half right.

[nfc]

Seems like a great project. Are you nfc1 at shapeways? If not any idea who nfc1 is? Many IBM Model parts
https://www.shapeways.com/shops/nfc

I'm nfc1 at shapeways

[Game Theory]

Seems like a great project. Are you nfc1 at shapeways? If not any idea who nfc1 is? Many IBM Model parts
https://www.shapeways.com/shops/nfc

I'm nfc1 at shapeways

Your Model M stem must have taken a long while to model!
https://www.shapeways.com/model/1180046 ... terialId=6

I've been doing some preliminary modeling [not IBM] using openscad but have been having some memory issues with spherical tops.

[Findecanor]

Model M caps are higher than Cherry MX caps. The top of the spring is inside the keycap's skirt. If you did an adapter for buckling springs, there would be a gap at the bottom.

[warty]

Findecanor: ah, bummer. Whelp, was worth a shot.

Thanks for the brain power everyone.