Building a Corne low profile keyboard

· geekery ·

I managed to build my own keyboard!

The backstory

As you may know, I’ve been using an ErgoDox EZ keyboard for a while now, and I have come to love both the ortholinear split layout of the keys and the ability to completely customise the key layout. They recently also enabled you to set up a layer to work with the open source stenography software called Plover. This was fabulous, and I have been playing with learning stenography using this layer. I’m sure I’ll be writing much more about this at a later date, but — briefly — stenography requires you to hit multiple keys together (like a chord on a piano) in order to output words phonetically. This means that it is easier to do if your keys are close together and don’t require too much force to press, otherwise your fingers are effectively bench-pressing a couple of kilograms every paragraph! Since my ErgoDox has hot-swappable keyswitches, I did a little experimentation, buying some Gateron Clear switches (linear, 35g switches). They definitely solved the force problem, and I was surprised to find how much I enjoyed typing on them for ordinary typing. As an aside, I think my love for the Happy Hacking Keyboard switches made me think that I could only love tactile switches, but now I think that they have their own special properties, and that I generally prefer linear switches.

Going down a bit of a rabbit hole while on holiday (as I am prone to doing), I started looking around to see if there might be some low-profile keyboards with key arrangements which might be better for stenography so that I could play with it further. Luckily, stenography requires very few keys, and I quickly found the Corne or crkbd keyboard, which is split, ortholinear, and has a layout well suited to stenography (as well as conventional QWERTY layouts). You can buy them assembled from various places, but it is much cheaper to buy a kit or components and make your own. This obviously requires soldering. I had never so much as picked up a soldering iron before this point, but I had always wanted to learn. As another aside, one of the consequences of coming out the other side of the menopause seems to be that I am much less worried about failure. I feel much more confident about trying things, even if they might be a bit challenging, and I might crash and burn. Perhaps I worry less about what other people think. I’m finding this new state of mind hugely enjoyable (which is good, because going through the menopause was hell, physically and mentally, so it’s nice to find something positive on the other side). So, why not learn how to solder and go for it?

The practice project

I was feeling confident, but I didn’t want to waste money or get frustrated by going straight into a complex/more expensive project like building a keyboard. Instead (after watching a lot of YouTube videos of soldering tutorials, and buying a £15 basic soldering kit), I got this cheap kit to build a little game demonstrating Conway’s Game of Life. It was fun to put together, and I was amazed when it worked first time.

I enjoyed the soldering a lot, and since I had already succeeded in the kinds of techniques I would need to build the keyboard (like ’through-the-hole' soldering), I had the confidence I needed to go ahead with the bigger project, without worrying that I would mess it up completely.

The Corne keyboard

After getting hold of all the components I needed, I got stuck in. There are a lot of ‘build logs’ out there where people document what they have done and problems they have encountered, so I had a reasonable idea about where the difficult spots might be. I took my time, trying not to spend too long soldering in one stretch, because it’s when you get tired that you tend to make mistakes (as I have found repeatedly while sewing).

I used a Corne Light v2.0 PCB, which enables you to use a wide variety of switches, but doesn’t support LCD lighting or hotswap sockets for the key switches. Both of those would be nice to have, but doing without them made the project much simpler and cheaper. I did however choose to use two OLED displays and two Elite C micro-controllers (which are USB C) rather than the standard Pro Micro controllers which are micro USB. I went for Kailh Choc Blue switches, which are low-profile 25g linear switches. The case is a simple FR4 plate case, and the keycaps are MBK Choc low profile key caps.

The whole thing went remarkably smoothly. I decided to socket the micro controllers and the OLED units so that I could remove and replace them if they went wrong, or if I wanted to salvage them for another project. I was a bit worried about doing this for the OLEDs: they had header pins already soldered on, which meant doing some desoldering, which I hadn’t practised. Again, it turned out to be a bit easier than I feared, so I was able to make longer header pins from the diode legs I had already trimmed, and plug it into the socket header I soldered in to the board.

Once you have the diodes, the controllers, and the reset switches and TRRS jacks soldered, you can try shorting out the sockets of each of the keyswitches in turn to make sure everything is connected up properly. I was holding my breath for this step, but it was a great feeling when all the keys reported back properly. From there, all I needed to do was insert all the keyswitches and solder them, then assemble the case and keycaps and try it all out.

The end result

I’m so happy with the end result. The keyboard feels comically tiny compared the ErgoDox, but with the reduced number of keys, every key is only one unit away from your fingers on the home row. They Kailh Chocs feel lovely, and the whole thing has a solid and good quality feel. It has probably taken me longer to wrestle with QMK to get the layout right (and the Plover stenography layer working) than it did to physically build the keyboard, but having done so, I am really enjoying typing on it.

When using QWERTY, it takes a little while to get used to the fact that there is no number row, so you need to use one of the layers to enter numbers and use function keys. However, once you have adjusted to this, it is no more inconvenient than using a shift key, and means that you can arrange characters wherever feels most ergonomic. I have learned from using the ErgoDox what arrangement of symbols etc. works best for me, so that influenced my choices heavily. I thought I would miss all those extra keys, but actually it doesn’t feel limiting.

Now that I have got my Plover layer working, it is a joy to be practising stenography on this board. The finger placement and the lighter keys make it much easier to type the chords needed accurately. For some sounds, you need to press several adjacent keys with one finger, and that’s much more comfortable on this board. I’ve got it set up so that I can activate the Plover layer from my ‘Adjust’ layer, then exit Plover back to QWERTY by pressing another key.