Button caps

[Druzyek]

I'd like to make a small keypad with a lot of buttons. I have used 6x6mm tactile buttons like this before:

(Random file from Google)

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I would like square button caps but I can only find round ones like in the picture for 6x6mm buttons. Has anyone ever seen square ones for that size? (I see a lot for 12x12mm buttons). I have not had any luck on eBay, AliBaba, or Amazon.

Thanks!

[GARTHWILSON]

lots of colors, different styles:
https://www.mouser.com/Omron/Switch-Bez ... cdZ1yzsaer
We used them for a couple of our products years ago.

[Druzyek]

Thanks, Garth. I wonder if I can etch characters into those with a laser cutter

[GARTHWILSON]

If you find a way, I'm sure you'll have some customers (like myself). I got some of the bigger ones, in colors, with the idea of using transfer lettering and then a coat of Varathane or something like that over it; but I don't know how much wear that will stand up to, and I know it yellows gradually.

[Druzyek]

I had really good luck etching with a laser cutter into stamp rubber and putting that over a keypad.

I want to make something smaller though, so I don't think that will work this time. I noticed that the square Omron caps are only 4x4mm. Not sure why 6x6mm square caps are so hard to find...

Some of the 12x12mm buttons have transparent caps you can put a piece of paper under which is really cool.

One idea I had was printing button names on membership/library card type material and gluing those onto round caps. Not sure if those would hold up very well and the places I looked were $100+ for minimum 250 cards 0_0

[GARTHWILSON]

There were various calculator and pocket computers with that size of keys, and although bigger keys are nicer, these didn't look that bad. This is one of the Tandy ones from about 1980 or so:

[Druzyek]

Ya, that is really neat. I used to be fascinated by those old handhelds and I added a PB-2000C to my collection at one point but eventually sold it. It was one of the coolest machines I ever owned.

I would love to make something with a keypad like that but I have no clue how a hobbyist would go about it.

[GARTHWILSON]

I hope that eventually the price will come down like PC boards have, to where they're quite practical now for hobbyists to get their own made. Just imagine double (or triple)-shot keys, and bezels with rectangular cutouts, and lexan overlays, all with set-up costs that are just pocket change, so you could do this kind of thing very inexpensively:



The keys on that thing have a wonderful feel, BTW! This hand-held computer was way, way ahead of its time when it came out in the 80's. I have two of them.

Although I'm not really fond of rubber keypads, it would be nice if those would also get to where you could get them made with very low NRE.

A neat thing about lexan overlays, which we took advantage of in one of our products is that you can have dead-front panels, meaning you can have annunciators that are pretty much invisible until a bright LED turns on behind, then the letters pop out of the black. We did that because this aircraft intercom had features and annunciators that might not apply in all aircraft, and it would seem kind of silly to have lights that never came on for certain aircraft. The way we did it, the pilot or aircraft owner wouldn't even need to know it was there if those modes were not applicable in his case. The lexan panels also allow tactile or smooth buttons. These are not suitable for typing, but they're good for some situations where you want to keep contaminants out of the key switches (like a machine shop with all the metal shavings and cutting oil) and just clean the keypad with a damp rag, even spraying it with a cleaner if necessary. The panel can also have a window for a display, protecting it from contaminants too.

[John West]

GARTHWILSON wrote:

I hope that eventually the price will come down like PC boards have, to where they're quite practical now for hobbyists to get their own made.

3D printing is almost there now. You can get high quality detailed single-colour plastic parts printed for you, at quite reasonable prices. There are printers that will do multi-coloured plastic, but I'm not aware of any 3rd party services that offer them yet, and the printers themselves are very much not at the hobbyist level.

I've got a model from one of the new printers here. The quality is not as good as injection moulding - there's visible layering (if you look close), and the colours bleed a little. But for a non-commercial hobby project, it's more than good enough. I just wish I could get my own designs printed on it.

Injection moulding still has very high set-up costs, and I don't see that changing any time soon. It's all about volume.

[BigEd]

You might find this kit interesting - transparent keycaps which allow for labels inside.
http://www.hpmuseum.org/forum/thread-57 ... l#pid80515

I'm guessing the keycaps are about 8mm square.

One thought: the advantage of smaller keycaps in a sparse grid is that a fat finger can press one button and two gaps. In effect, you get more finger space with a sparse keyboard, at the same key pitch.

[whartung]

GARTHWILSON wrote:

The keys on that thing have a wonderful feel, BTW!

Yea, you need more than just keycaps to make a good keypad/keyboard. HPs were some of the best.

I think, today, multicolor 3D printing is the way to go, honestly. It's perfect for one off small manufacture.

You can perhaps reduce costs by using a sprue method of combining a number of keys in to a "single" model that's then printed whole, and then the keys are clipped off the tree. Depending on the printing tech, you may be able to send the keys as a single "model" but in separate parts (though, with the sprue method there's less chance of the printing company losing a key).

Quick google: https://www.thingiverse.com/glitchpuddi ... -mx/page:1

[GARTHWILSON]

BigEd wrote:

You might find this kit interesting - transparent keycaps which allow for labels inside.
http://www.hpmuseum.org/forum/thread-57 ... l#pid80515

I'm guessing the keycaps are about 8mm square.

One thought: the advantage of smaller keycaps in a sparse grid is that a fat finger can press one button and two gaps. In effect, you get more finger space with a sparse keyboard, at the same key pitch.

Those look similar to the Grayhill 87 series keys which are somewhat attractive, not the most attractive, but you can put your own labels under the transparent keycap. The data sheet is at http://www.mouser.com/ds/2/626/Keypads_87-334536.pdf . I've used them in a few different things like the in-house 6502-powered automated test equipment in 1990 (where I did not make my labels look particularly neat):



the control head for a later product in 1993,

and my early efforts at a portable workbench computer:


I saw them also on an organ console in a college chapel in our city.