I like the idea of a slim mechanical keyboard. Cherry ML switches are one of the few options for a slim switch. I picked up a G84-4400 for cheap off eBay. As others have noted, they're not great switches. And the layout of the keyboard made some odd choices. After I got into orthlinear keyboards, I thought it might be fun to use the ML switches to make a second Atomic board and make it as thin as I could. This is the result.
Instead of trying to design a PCB, I decided to do a hand-wire with a steel backplate. The ML switches aren't designed for plate mounting. So I designed the plate with cut outs for the pins and sent it to Lasergist. Here's the plate with one switch in place for testing.
All of the switches mounted and glued.
Here's what the back side looks like. The switches include jumper pins. I bent those down to hold the switch in place while I glued it. The switch pins are on the top and bottom ready to be wired.
Here's the hand-wire. It's a bit sloppy. The vertical pins make it a little more difficult as I can't just put the columns in straight. I could have switched it with the rows wired together and the diodes on the columns. That probably would have been cleaner. This is connected to a Teensy 3.2 which sits in the blank area above the keys and running the Kiibohd firmware. Many people put the controller under the switches. But that would require additional space and I'm trying to keep things thin. The micro USB port on the Teensy helps but is stil the thickest part and keeps me from making it thinner.
The result is pretty thin although it could be thinner. For now, I just cut some nylon spacers for about a 5.6mm gap. I plan on getting some acrylic cut from Ponoko to finish the sandwich case at some point.
Here's the USB port and you can also see the controller and wires all crammed in there. The case does bow slightly due to the thickness of the controller USB port.
Bottom side with taller feet than I would like but they need to keep the nuts from touching. I should also have made at least one more hole in the front middle to hold it together a little better.
Comparison with my OLKB Atomic keyboard. I have both layouts setup the same. I'm currently playing around with some relegendable keycaps on the Atomic.
It is shorter then the Atomic. Although the Atomic is currently just sitting on a piece of foam as I don't have a case for it yet.
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