need feedback on first plate design

[fengshaun]

Good morning/afternoon/etc. to everyone,

I'm trying to get my feet wet with DIY keyboards and I have just drawn a hopefully-semi-correct design of what I want to produce as my first project. To start, I have taken the key64 project's left hand and drew on top of it and modified it a little bit to accomodate what I'm trying to achieve.

In the attached picture, the red square is 14x14mm (cherry mx spec for switch mount cut) and the outline is where the keycap is supposed to go (every unit is 19.05mm, so I just multiplied the number: 1.5u = 19.05x19.05*1.5mm = 19.05x28.575mm).

I just wanted to know if I'm in the right track and whether I'm doing something horribly wrong. Most importantly, I want to know if I have the right idea about any measurements involved (for switches and keycaps). Any and all feedback is appreciated!

Thank you.

P.S. I drew this in inkscape and I have the original SVG file if you need it. Let me know how I can post it!

EDIT: This will be hand-wired, so I won't be using a PCB! This plate is the only thing holding the keypad together!

[tlt]

Looks fine to me. If you are going to hit the 2U caps on the edge of the cap with the thumb it might not feel as smooth as other keys.

[bearcat]

Those measurements are correct.

BTW, depending on what you're cutting it with, don't forget the width of the kerf. Even a laser has a kerf...

[fengshaun]

Thanks a lot!

@tit: what keycaps would you recommend? I was thinking I would put black mx switches for the thumb keycaps and then rest my thumb right on top of the middle one.

@bearcat: I just looked up kerf! Should I reduce the width and height of the switch mount (red area) by harf of the kerf length and everything should be fine? I guess the exact kerf length depends on the laser machine itself! (This is going to be cut in acrylic, if that makes any difference!)

[Findecanor]

I have had 1.5 mm thick acrylic plates lasered at Ponoko without adjusting for kerf, and the switches fit fine but the stabilisers were too loose. Mind you that I also had a PCB and I used spacers between plate and PCB to prevent flexing, and the PCB is sturdier than the 1.5mm plate.
For direct wiring, 1.5 mm acrylic is not strong enough. With a thicker plate, the switches will only be force-fitted, not snapped in place. What I think you could do (and I wished I had done) would be to make a sandwich of layers glued together, with switches snapping into the top layer and with the lower layer(s) having larger holes but then you may have to use coloured acrylic and epoxy (superglue fumes fog acrylic) or paint the assembly to make it look decent.

[fengshaun]

I feel like I have a lot more to learn about this. How about a mount plate (1.5mm acrylic) and a base plate with holes for attaching the two plates together. How would I be able to do that? It would look like this:

----------------------------------------------------------- <- mount plate (1.5mm acrylic)
| | | | | | <- "spacers" throughout
----------------------------------------------------------- <- base plate (also acrylic)

What can I use for spacers to also attach the two plates together without glue?

EDIT: it seems like some people are using "sex bolts", is that what I should be looking for?