BK-1

By Asa Gilmore

Before I get into the project I want to give credit to the two projects which inspired this keyboard, both the Mikefive, and the Caldera keyboards. Please go check out both of their projects as they are both really great!

I started my journey with ergonomic keyboards building Christian Selig's Caldera keyboard. Switching from a regular keyboard to a split ortholinear keyboard was a huge revelation. I think Cristian Sellig has found the perfect layout with his keyboard, but there were a few things about the Caldera keyboard that kept it from being the perfect keyboard for me. One of the primary issues was the switches. This may be an unpopular opinion, but I much prefer the feel of a laptop style switch, I don't like to make my fingers do any more work than they have to, and the binary feel of a laptop switch makes me much more accurate than a mechanical switch with longer travel. Also using taller switches without a bulky wrist rest makes your wrist bend reducing comfort. When I saw the Mikefive with a total height of under 5mm, I knew I wanted something similar.

Design

There are some key design ideas that come from how I specifically use my computer that guided this build. While I totally understand the appeal of a more traditional ergonomic keyboard like the Kinesis for someone who writes code all day, as a data science and machine learning researcher, and a Student, I frequently switch between input tools during my workflow. I am often jumping between working with 3d neruoimaging data, cad modeling programs, and alternating between pen and paper and a writing math in LaTeX. Because of this I want switching between different input devices to feel really seamless. I want my keyboard to feel like an invisable interface between me and my computer, as opposed to the centerpiece of my desk.

Because the BK-1 sits at the same height as my trackpad, flicking my wrist over to make a mouse input feels seamless and intuitive. The split design allows me to position the board around a notepad or any other items on my desk depending on my workflow. The short and snappy Kalih PG1316S switches feel comfortable and familar coming from my MacBook keyboard. Overall I think the goal here it to make the keyboard feel like a seamless component of my overall workflow, as opposed to the de facto to engage with my computer.

Engineering

The design of this keyboard borrows its layout from the Caldera Keyboard, with a slight change made to the amount of column stagger, most notably, more stagger on the pinky row. It uses the Kalih PG1316S switches surface mounted on a 0.8mm PCB, with a unibody aluminum chassis surrounding it. Each half has a Nice!Nano v2 and a 110mah LiPo battery, resulting in about a week of use between charges. The case is attached with 4 M.2 screws, one of which has to be the slightly hard to find countersunk M.2 x 2.5mm screw. JLC PCB and CNC was used to order the parts, as they have absurdly cheap CNC pricing. The case is definitely a bit overcomplicated, but I really wanted to minimize the length of the case to keep it a more square aspect ratio. The inside has some weird cutouts for the battery and overcomplicated screw placement, but it works and is hidden from the end user!

Fitting the MCU and battery was a bit of a challenge, but the column stagger allows for the MCU to fit lower on the left side, and using a small 110mah batter means that there is not too much of a forehead on the board, though I think there is room to make improvement in this area. The screw placement is a bit unorthodox, as I wanted the corners of the case to come up next to the switches without any padding, but because the boards is small, it still feels super sturdy. The battery just fits on top of the PCB with some double-sided tape.
The total cost of this board is ~$250, which is a lot. The cost could be brought down a lot with a cheaper MCU, bulk ordering of the case + switches.

I used this cheap hotplate to solder it, which worked great, although it's a bit small.

Keymap

Keymaps are likely something each person will customize for themselves, but I will share how I like to set up this keyboard. It's pretty straightforward, with a single mod layer. The mod key is on the left hand, and maps arrow keys to the resting location of my right hand, and some maps some frequently used coding characters to the left hand.

Avaiabilty

In the files folder you will find the .STEP file for the case.

The PCB files should be good to order as is, just make sure you order a 0.8mm thick board.

The cad files for the case are also straightforward to order, I ordered them from JLC cnc, with 0.1mm precision. The drawing is needed for tapping the holes as well.

I also have a few extra PCB's due to the minimum order quantity on JLC. If anyone wants to take them off my hands create an issue on this repo to get in touch with me.

Improvements

• I worked for a while to try to fit a bigger battery into this board, but ultimately couldn't find a way to do so without adding a comically big forehead, so for now we're stuck with a 110mah battery.
• The keycaps provided by Kalih are flat, A custom keycap that has a subtle dish to it would make typing more comfortable. It looks like the mikefive project is working on some resin printed keycaps, so hopefully that is an option soon!

Support

If you end up building your own, and you feel like I've earned it, any support would be greatly appreciated. Feel free to contact me at the email below if you want to get in touch with me about collaborating to commercialize this build.