The case is made of six layers of 2mm (12th of an inch) plywood (formerly 5x3mm). This makes the case slimmer (12mm instead of 15mm) and way better looking.
Three of those layers are glued together (with wood glue) to form the top part of the case:
- top layer: for looks, stability and protection
- plate layer to hold the switches
- frame layer 1
The bottom part of the case consists of the remaining three layers:
- frame layer 2
- frame layer 3
- bottom layer
Both parts are screwed together using regular counter-sunk screws 12mm in length (half an inch).
While planning the keyboard I built a prototype and tried to use metal screws and counter-nuts. The problem is that this requires a lot of precision and additional bolts to avoid sideways movement and that makes it way harder to build. So I went with the wood screws again.
The three frame layers plus the plate layer provide 8mm (3rd of an inch) clearance for the switches. Cherry MXs require 8.3mm so that’s doable.
A unintentional but most welcome side-effect of the slimmer design is a drastically reduced noise level. Wooden keyboards are known to be loud. And they are, no doubt about that. There’s a reason so many musical instruments are made of wood after all. Turns out reducing the amount of air volume inside the case also cuts down on resonance. This makes the keyboard much quieter. Reducing the clearance below the case, i.e. the height of the rubber feet, reduces the noise level even more.
Here’s how I went about building my wooden plywood case.
- create template on the computer
- print out design on paper and make sure it has the correct dimensions
- measure its overall width and height (colors for the different layers; black circles are screws, pink Xs are rubber feet)
- cut bigger board into pieces according to measurements, leave room for errors. I had a 100x50cm^2 board (40″x20″) from which I could cut nine pieces of 30x16cm^2 (12″x6″) and had plenty left over.
Track the orientation by marking the pieces. Flipping or rotation individual boards would cause the color of the end pieces to differ.
- in each step transfer the template to the board:
- lay the template on the board
- punch through vertices with a spike
- draw lines between punched holes
- cut the layers into shape (outer shape of the case) all at once. Leave a little room for error (at least 1mm). If you leave too much room, you will have more work later when sanding. If you leave too little the wood may become too thin and break.
(In this build I had planned for a 3.5mm frame on the top layer but ended up with 2.5mm, which is on the verge of too little. There are a lot of things that affect the outer shape. Cutting may be poor and/or cause splintering, layers may shift slightly, etc. All this made me sand off 1mm more than what I had planned for.)
- cut the frame layers, get used to saw. Keep the cutouts, will need them when sanding.
- cut the plate. This might seem like a lot of work but it really is not. A good portion (around a fifth) of the time goes into drawing the lines. E.g. lines indicating where to cut and additional lines around them to help keep the orientation. After cutting a hole test it by seating a switch. Refine with a file until it fits.
- cut the top layer. Here again leave room for error. Keep the cutouts as well.
This thing is as much work as the plate layer. The keycaps must fit and it has to look good. Clamping the top layer to the plate layer and using a switch with keycap helps testing all positions, especially corners (that’s why the plate layer is cut first). Make sure everything fits. Reworking after gluing is possible but way harder.
- glue the bottom three layers together, glue the top three layers together, let them dry.
- clamp both parts together and carefully drill holes for the screws.
- take the cutouts from the frame-layers and put them back in. The cutouts will support the blade while sanding. The last thing you want is to break the plate.
- screw together
- start sanding. In this case I found it way easier to take the case and scrape it across sandpaper than the other way round. It makes it way easier to get the angles right. Hint: Glue sandpaper on a board and fix it to your workbench. (I forgot to take a picture this time. So here’s one from my previous build, where I had not yet put in the cutouts)
- sand even more using ever finer sand paper. How fine you want to go depends on the finish. For varnish 400 grit is sufficient. For oil I would recommend higher grits of 800 and beyond.
- take the case apart
- apply varnish or oil. This might involve several iterations of sanding and applying varnish. I applied three layers of varnish in this build.
When applying varnish be mindful that it takes up space. This is important for the seam between top and bottom part of the case. Here I only applied varnish once and completely sanded it off again, so the layer heights were kept consistent.
- add switches
- add „pillars“ to support the plate
- glue the switches to the plate. Last time I used hot glue this time wood glue. The former is stronger, the latter is almost invisible and requires no space. The both work, but I’m sure there are better alternatives.
- screw together
- have fun!