Case for Preonic Rev 3 Keyboard

I recently bought a Preonic Rev. 3 from Drop.com (Shameless plug: https://drop.com/?referer=ZER4PR) and couldn't wait to build it. Unfortunately, I didn't do enough research to find that the Rev. 3 PCB would not fit in the Rev.2 cases and most of the examples of handbuilt cases were for older models. So I found myself wishing that I had bought the acrylic case while I could. As soon as my green Gateron switches came in I went to designing a case that would accent the underglow LEDs (the process to add those will be another instructable coming soon!)

• 1/4 inch Polypropylene Sheet Frosted Clear
• 3D Printed Mid Piece (I used MakerBot PLA Cool Gray)
• The hardware that comes with the plate and PCB kit from Drop.com
  • 5 1/2 in M2 screws
  • `2 1/8 in brass hex spacers

To accent the underglow I knew that I needed to use some kind of clear plastic material. My First thought was plexiglass, but when I went to look for materials I had available I found this 1/4th inch thick plastic sheet and a 1/8th inch thick piece of plexiglass and knew that this would look better and lift the keyboard up a little more off the desk which I prefer.

I started by using my plate to mark out where to cut and shape the bottom plate as well as where to drill holes for the screws to attach the PCB. The angle is small enough that I didn't need to adjust measurements much. I used a large sharpie and cut outside the marked line to make it slightly larger than the plate. Then I cut it with a jigsaw and plexiglass saw blade. I cleaned the edges up and rounded the corners with a Dremel and sanding wheel. The edge was fairly dull after this so I used a soldering iron to lightly melt the edge to a slight shine.

I drilled the holes with 1/16th inch bit, but found these to be too tight. I then went back and used a 3/32nds inch bit and angled just a bit to account for the angle of the PCB.

I prefer a slightly raised keyboard and the keycaps that I chose were Cherry profile, so I tried an idea that worked out far better than I hoped. I placed 2 of the brass spacers from the kit, that were meant to be in between the plate and PCB when using the "extra secure" plate method, on the top two mounting screws. I then attached the PCB with all of the other screws. This created a slightly raised angle that set the middle row perfectly horizontal. I measured the rise from top to bottom for modeling the Midpiece and calculated the angle to be 2.75 degrees.

With my partially built board (which I started using immediately,) I started to make a Midpiece that would be tall enough to reach the bottom of the keycaps. I used the model created by Jack Humbert on github (https://github.com/olkb/olkb_parts/blob/master/preonic/hi-pro-bottom-rev3.stl) to start. This simplified the process of fitting the plate. I imported this into Tinkercad and removed the bottom. I then increased the height of this midpeice to the measured height of the R1 keycaps and cut an angle from the top to match the R5 keycaps. Lastly, I increased the height of the notch for the USB C connector. This resulted in this model.

I printed this on my Makerbot Replicator 2X with a .3mm layer height, 1 shell, and 15% infill using MakerBot Cool Gray PLA which almost matched my keycaps perfectly.

Finally, I placed the Midpiece over the plate and pressed down on each corner until it met the bottom board. I may glue it down later, but for now, it's held in place just by the friction with the plate. That's it. I will add links to another instructable on adding LEDs to the keyboard for underglow soon. Hopefully, there will be more case options available for the Preonic soon. My next project may be to make my own wooden case.