bunchiez40

An experimental ultraportable keyboard that uses mouse switches to achieve a compact form factor while still being viable as a daily use keyboard. Board can be hand soldered, and case can be 3D printed or CNC'd.

Has science gone too far?

Status

v0.0 PCBs confirmed to be working! Happy to open up this project for others to play with

About

I hit the limit as how small I could go with choc switches. I found that kailh mute switches are an ideal small form factor alternative in terms of their size, durability, and actuation force. To make this board more accessible to build at home, it uses a rp2040-zero board that can be soldered on.

More details about my research on mouse switches and experience with the bunchiez40 can be found here: https://chrischrislolo.github.io/orthoLabLogs/bunchiez40-how-i-built-a-keyboard-using-mouse-switches.html

Case files include STLs, STEP files, as well as source OpenSCAD files that can be modified. The OpenSCAD models do not have fillets on them

Case

The case files can be found in the case directory. The particular files you'll want are the case_holes file for the top part of the case, and the case_holes_floor file for the bottom part. CNC and 3DP works with the top part of the case, and I chose to 3DP my case bottom.

PCB

You can find the PCB source files in the pcb folder. The BOM files can be found in this folder.

Directory Structure

• case You can find the files you need in this folder to print out a case for the keyboard
• drafts Stores any KLE or intermediate information used in making the case
• outlines Outlines used to create the case and pcb
• pcb Kicad project relating to the project

BOM

• 1 PCB
• 1 Aluminum CNC upper case or 3DP upper case
• 1 lower case. I 3D printed mine
• 16 3mm M1.6 screws (go for flathead for a flush fit, though other head types should also work)
• 4-8 (ideally 8) 1-2mm bumpons (something like Sj5302 is a good place to start)
• 1 0.91 inch OLED
• 1 rp2040-zero pcb
• 40 Kailh/Huano 7.3mm mute switches (ideally with some spares)
• 40 LL4148 diodes (ideally with some spares)

Assembly

Build guide coming soon. For now, hopefully the footprints make it clear as to what should go where. Note that the rp2040-zero should be placed in such a way that the MCU is on "top" of the pcb when the assembly is face up, like such.

Once all parts have been assembled, the board can be screwed onto the top of the case with 8 screws.

The firmware should then be flashed onto the board.

The bottom of the board can then be screwed to the case. My recommendation is to put two bumpons on each corner of the bottom of the case, one above the screw and one beside the screw. This helps maximize stability.

Firmware

QMK Firmware can be found here https://github.com/ChrisChrisLoLo/vial-qmk/tree/sporewoh/keyboards/sporewoh/bunchiez40