Prototyping alps plates using card stock

[jacobolus]

Hi folks,

Well, after a few months doing other things [moving, switching jobs, a couple of trips, etc.] I’m finally getting back to work on keyboard design projects.

Last time, I made a plasticine model, but I decided that it would be a lot easier to prototype if I could actually press keys down.

I like the old orange alps switches from Apple keyboards of the late 1980s (e.g. the “Apple Keyboard” M0116 and the original “Apple Extended Keyboard” M0115) much better than any of the Cherry switches I’ve tried [red, brown, blue, clear], although I could live with clears if I had to. So I obtained a few of those keyboards and desoldered all the switches.

The switches were originally mounted in a steel plate ~1.25 mm thick. I’m prototyping new plate layouts using a stiff card stock ~1.45 mm thick, since I don’t want to go to the trouble of cutting steel until I know where to cut the holes. It’s actually working quite well: the switches stay in and there's enough rigidity that when some stabilizers are added typing should work okay for a few days/weeks of moderate use. Here, have a picture:


Basically, I just lay the previous plate down on my card stock, trace the inside of switch holes using a pencil, and then cut with a utility knife [with the plate still there so that I can cut along the edge of the hole].

I’ll go through a few iterations just cutting and testing without plugging anything in, and then I’ll add another piece of cardstock with holes for the switch leads to add for rigidity, and try soldering the ends of the leads all up a matrix of wires/diodes, so I can test really using the keyboard to type on.

Obviously the feel is going to be slightly inferior to a metal plate and proper case, but I think it’ll be plenty good enough for rapid testing. Then once I have a design figured out, I can come up with a way to get a metal plate cut.

Anyway, as you can see in the picture, for my hands at least, the most natural place to put finger keys so they can be typed without unnecessary wrist movement is quite different from the way keys are usually laid out on a standard computer keyboard. I actually wanted a slightly more extreme staggering / horizontal spacing, but my girlfriend has smaller hands and had a better time reaching to the corners when I toned it down to the version in the picture.

[Note: ignore the labels printed on the keys. I just used a roughly qwerty layout to get the right keycap profile for each row]

The general idea is that the finger keys will be on a plane tented up in the center and also slightly up at the near side. Then the thumb keys will be in a separate plane roughly parallel to the table. I haven’t made that part yet though.

I’m writing here, partly to show progress, and partly to tell anyone prototyping plate layouts to use alps switches on card stock: it’s so much easier to try new designs with a utility knife than a laser cutter / CNC router / whatever! And so much easier to cut out simple rectangles than the fiddly shape of cherry switches!

[yasuo]

Really nice so neat,you cut
you will make ergo kibord like Btron

[jacobolus]

Ooh, good point. I can probably add another ring finger key like the Btron keyboard. Thanks for reminding me to look at a picture of it again!

[jeffgran]

cool! I've never tried any ALPS switches but this technique could be used for cherry switches as well. The fiddly shape you refer to is only necessary if you want to be able to disassemble the switch while it's still in the plate. If you're just prototyping, a square would work for cherry switches too. But either way this does seem like a quick way to do prototyping. Thanks for posting.

[jacobolus]

Another try, this time with the extra key for the 4th finger:

[jeffgran]

Have you found that the splayed columns work better for you than regular side-by-side staggered columns? I'd never thought of doing the fan-pattern like that and curious to know if you've tried both and like this way better.

[jacobolus]

I haven’t received my order of diodes, so I can’t actually matrix this up and try typing on it yet. I’ll get back to it after the holiday [sometime in mid January], and let you know how it goes. I put the keys in a splayed layout like that based on observing the way my fingers naturally move if I flex/extend them.

[jacobolus]

Okay, after a month of various traveling out of town, etc., I’m back to it. Still some work to do figuring out the thumbs, but the card stock method is working really well so far.

One layer for the “plate”, with the usual rectangular holes cut to hold the alps switches. Then a couple of layers of “spacer” card stock, using pieces cut from scraps, and attached to the plate layer using hot glue:

After that, one more piece of card stock with holes cut for the switch leads. Then I hooked up the “columns” of the matrix using the leads of my diodes, and the rows of the matrix using some insulated wire.

Now I just have to finish hooking up each column and each row to the pins of a teensy, and load some firmware on. [And then do the same thing for the other hand, and the thumb keys.]

One more picture of the front:


But overall, this is much easier than trying to make a custom plate and/or PCB to prototype. It still takes several hours to work all the way through it, but iteration can be very fast, maybe 1-2 iterations/day if necessary. [Or much faster iterations still if it’s just cutting the cardboard and immediately noticing that the keys aren’t comfortable to hit.]

The result is actually entirely rigid enough to type on [especially if another layer of something hard like wood/thick plastic/metal is added below the wiring]. It’s obviously not as pretty, finished, or sturdy as a “real” keyboard, but for prototyping it’s entirely satisfactory.

Then once a design is figured out, it should be pretty easy to turn into CAD files for making custom case/plate/etc.

[yasuo]

Really nice Like this but with MX
http://www.esrille.com/keyboard/