Internal WireSplit Keyboard

Sketch and concept

Decide the key count, split shape, size, thinness, and overall appearance. At this stage, the goal is not precise dimensions but deciding what kind of structure you want to make. This is the most enjoyable part of the process.

Note If the direction is vague here, later steps tend to create more rework.

Wiring diagram

Organize the key layout, row-column matrix, MCU, I/O expander, and left-right connection wiring. This affects the wiring routes in the later 3D design, so leaving it vague can break the later steps.

Note The mechanical structure and electrical design cannot be separated.

3D modeling

Design the top cover, switch plate, base plate, and bottom case. The wiring grooves, PCB socket positions, screw holes, and insert nut positions are also decided here. Insert nuts should be treated as something that may fail, so the structure should allow multiple fixing points.

Note Because the wiring route is decided here, this design step changes the difficulty of the whole build.

Parts list and tool preparation

Organize the required parts and tools: switches, PCB sockets, MCU, I/O expander, wire, screws, insert nuts, and soldering tools.

Note A purchasing mistake stops the work, so preparing the list matters.

3D printing

Print the parts and check dimensions, strength, and fit. Printing takes time, and failed prints or unsatisfying shapes make this one of the hardest steps.

Note Proceed with the assumption that revisions will be needed, not that the first print will be final.

Test assembly

Temporarily assemble the switches, sockets, case, and screw positions. Check for interference, floating parts, misalignment, and awkward assembly.

Note Skipping this step can create much larger corrections later.

Glue PCB sockets to the base plate

Fix the PCB sockets in their intended positions. If they shift, switch insertion and electrical contact can become unreliable, so positioning matters.

Note Misalignment is hard to correct in later steps, so this should be done carefully.

Wiring and soldering

Run the wires through the grooves inside the plate, position them in place, and then solder them. By fixing the wiring routes on the structural side, this design aims to improve repeatability during assembly and reduce the risk of broken wires or shorts caused by vibration or contact.

Note The key point is to manage the wiring routes with the structure, rather than using free-air wiring.

Programming

Configure the keymap, matrix, and I/O expander settings in QMK. If the hardware layout and pin settings do not match, key input will not be recognized correctly.

Note Hardware and software always need to be adjusted together.

Testing

Check every key input, the left-right connection, chatter, contact failure, and firmware settings. If something is wrong, correct the wiring, soldering, or program.