Contra 40% ortholinear keyboard kit
This is a very inexpensive kit from
Cartel.ltd that includes everything except switches and keycaps. The top and bottom plate are both PCB material with white soldermask. The kit was $30 plus shipping, this was through a group buy.
I assembled it using switches and keycaps recycled from a Leobog K22 104 key keyboard I got from Amazon for $17. This is the full grid layout with 48 keys. It can also be assembled with a 2U space bar. You will need to provide your own PCB mount stabilizer for the 2U keycap.
The bottom plate is a PCB. They used a solid copper fill on the bottom and used the soldermask layer to display their logo in reverse. The exposed area is HASL coated. The bottom is reversible, the other side is mostly blank. The 3M black rubber feet were included in the kit.
Side view of the three parts. The PCB is screwed to the bottom with M2 spacers and screws. The switch plate sits on top and is only held in place by the switches. The kit came with 8mm spacers. I used my own 5mm spacers with a washer (0.3mm thick) to make it as thin as possible. The tallest part is the USB connector on the Pro Micro. I could also make it thinner by using a thinner
Pro Micro. The black Pro Micro clone came in the kit, it is socketed in an ultra low profile socket.
The linear red K RGD switches from the Leobog keyboard. The plate and PCB should also work with Alps switches.
The switches have 19.05mm spacing, which is the standard. It also makes these parts incompatible with OLKB.com Planck parts which have 19mm spacing.
I added a WS2812B strip to the bottom. There is a 4 pin header to the right of the reset switch.
Ground, B1, F7, VCC. I used a
modified version of my GNAP! firmware on mine. The matrix is the same shape, just different pins. They also have an
online firmware compiler but it is very limited. You can export the JSON from there and upload it to kbfirmware.com where you will have access to more features, including support for the WS2812B strip.
Closeup of the 4 pins. I used B1 to control the WS2812B strip. The reset switch is a nice feature since the Pro Micro doesn't have one. Makes it a little easier to deal with the caterina bootloader. I
flashed my Pro Micro with the DFU bootloader.
All lit up. The white soldermask reflects the light well.
There are only 5 M2 supports. This is probably not enough for this board if you are a heavy typist. There is quite a bit of flex.
