Harpagon, a full sized DIY keyboard

[Narann]

Hi all, after having build my own (first fully DIY) Atreus keyboard, I realize I have a full size keycap set and 120 switches to use and wanted to build a full sized keyboard.

Here I am for now:



It will be wood (4 layers of 3mm each). I still have to check the  stabilizer sizes.

I did a wire schema:



33 pins: 12 (blue) + 21 (red)

But I could maybe decrease the number of pins considering the right side (arrow+home/end+numpad) as a continuation of the left row (saving 6 blue pins: 6 blue + 21 reds = 27 pins).

I will maybe need 3 more pins for LED but those are not a priority for now.

So I would need a 30+ pins usb microcontroller.

I used Teensy 2.0 for Atreus but realized it will not have enough pins (27). Maybe Teensy++ 2.0 (46). Have you any good and cheap microcontrollers that would match my project?

About the firmware, I succeed to use TMK with the Atreus and would use it again for this keyboard. Am I silly? Is there better firmware for full size keyboard?

As it's my first electronic project. Any advise is welcome.

As you can see, it's a lot of question.

A big thanks in advance for your time guys! I'm very excited about this project!

[Narann]

I did some printing tests:



I'm still not satisfied with the space between "F row" and "Num row".

[yoippari]

I'm still really new at this myself but I've been reading a lot. It looks like the teensy++ is useful for this size of keyboard. There was a prototype for a 122 key keyboard over here and it uses the ++.
Also there was a guy who used a layer of wood over a metal plate which worked but he had some warping over time. Just something to keep in mind.

[Narann]

That's why feedback are important! I will read this carefully!

Thanks a lot for those useful information!

[Marcel]

Hi,

Teensy++ 2.0 is a good choice, it would be more work to adapt the TMK firmware to another chip. At least you know it's working on this one.

Are you doing the plate or the case in wood ?
If you're using a plate, it need to be 1.5mm thick (see CherryMX datasheets).

As yoippari said, remember that wood is a living thing. I did my case in solid wood, and it moved a bit with changes of temperature and humidity. I had to file it a couple of time to adjust it. And the steel plate I use helped to keep it straight. While I was building it, the wood started to twist like crazy.

[Narann]

Thanks! I think I will go for the Teensy++ 2.0.

After some time reading GMK Firmware code, it looks more "community-driven" with many keyboard examples so I will maybe focus on it after all.

I will do it in plywood: 4x3mm or 3x5mm (but this looks dangerously thin). About wood. Maybe I'm wrong but because it's thin plywood, I shouldn't have too much trouble. Troubles seems to came for big ~1cm wood pieces.

Also, I use linseed oil + turpentine in multiple layers to let linseed oil get inside the wood. But yes, I will be wakeful.