Now you can assemble the keyboard. You've got four options here:
- No case at all, just raw PCB, Pico, keyswitches, keycaps, and a dream!
- 3D printed case
- Laser cut case using either acrylic or wood
- Combo laser cut and 3D printed case (a.k.a. "The Ice Cream Sandwich")
If you'd like to 3D print your case and switchplate, go ahead and get the model files from the link below.
If you'd rather use 2D dimensional drawings to laser cut, hand craft, or mill your case, use this .svg file linked below.
The key plate should be made from 1.5mm material, while the top and bottom can be whatever you like so long as you have the standoffs and screws needed. I made the top and bottom of my case from 3mm acrylic.
Solder the Pico
To begin, solder the Pico to the PCB. Heat up the joint between the two boards and then flow solder in, making sure to keep the boards aligned while soldering the first corner.
Solder all four corners and then work your way through the rest of the pads.
Test the Joints
Once the boards are soldered, use a multimeter in continuity mode to check the connections between each GPIO pin and its associated keyswitch.
It's a good idea to also double check that there are no shorts between ground and power pins.
The switch plate holds all of the keyswitches in places so they are stable and well aligned. Relying on the soldered pins and plastic pegs alone is definitely possible, but tends to lead to misalignment and wobbliness.
Add Switches to Plate
You'll need to push the keyswitches through the switchplate before mounting and soldering them to the PCB.
Orient the plate with the Pico cutout on the left and the reset switch cutout in the proper upper position.
Orient the keyswitches to match the PCB -- pins at the bottom.
Push the keyswitches through from the top of the plate, being sure they click satisfyingly into place. Careful about applying too much force to the acrylic or it can break.
Before proceeding, place the four M3 screws into the PCB mounting holes as shown.
These mount the PCB to the case bottom.
Seat the Switches
Carefully inspect each switch leg to make sure they are all straight. It's crucial to the next step that none of them are bent, or they won't seat properly in to the holes.
Align the switches with the PCB from the top and push all of the switches into place. Take it slowly and make sure none of the legs bend! You can use a thin pick/probe to help them along if needed.
If you have issues with a particular switch, squeeze its retention tabs and pull it from the plate, then adjust the pins and re-seat it.
Solder the Switches
Flip the board over and start soldering! Make sure you have a clean, hot iron, a ventilation fan, and some good quality solder.
Squeeze the key toward the PCB as you solder the first few switches to make sure they're fully seated (I did the four corner switches first). After that the switchplate should assist you in keeping things level and snug.
Make your way through all 42 solder joints like a boss.
This is a great time to test your work, before enclosing the keyboard in a case.
Plug in the Pico over USB and try out each key by typing into a text editor, or just watching the serial output of your code editor.
With the functional parts of the keyboard built and tested, you now get to add the keycaps and case. Such fun!
First, the laser/milled style case, then the 3D one.
Laser Case Bottom
Use the M3 screws and nuts to affix the PCB to the case bottom.
The patterns in the base allow for the keyswitch posts and soldered pin legs clearance for a nice flush fit against the PCB.
Laser Case Top
Add the four M2.5 x 16mm brass standoffs to the four corners, tightening the nuts from the bottom.
Place six rubber feet under the base as well.
Screw the case top onto the standoffs from above using M2.5 x 6mm nylon screws.
If you'd like to 3D print a middle section for this version of the case, use the file attached below.
3D Base Attachment
Place the PCB into the base, alining the M3 screws you added earlier to the holes in the base.
Use the nylon nuts to fasten them.
3D Case Top
Place the case top onto the bottom -- there are alignment posts to make it fit neatly.
Screw in the four M2.5 x 16mm screws from the top (or bottom, your choice). No nuts are needed, the screws will self tap into the plastic.