Knuckles

Knuckles

There are a lot of split keyboards out there, but most of the ones that piqued my interest don't have a number row, and I really like having one. I also wanted a slim ergo split that feels somewhat like a Magic Keyboard. Knuckles is my attempt at both.

Each half has 27 keys: a column-staggered 6×4 grid that includes the number row, plus a three-key thumb fan. It uses Kailh PG1316S low-profile switches on reversible footprints, a nice!nano controller, a JST-PH battery connector, and a power switch. The controller area also fits the HolyKeebs TPS43 touchpad module.

The first wireless PCB was ordered from JLCPCB on 2026-10-18. The exact files are archived in manufacturing/.

ergogen/config.yaml also still defines the original wired knuckles board (TRRS, small display). It's no longer supported. knuckles_wireless is the board to build.

A separate integrated nRF52840 revision adds on-board USB, charging and radio circuitry in dedicated left/right layouts. Its retained routed layouts and experimental firmware are engineering prototypes; module sourcing, manufacturing review and bench validation remain release gates. The normal build continues to use the nice!nano design.

Build it

You'll need Node.js 18+ (CI uses Node 20) and Git. Footprints live in a submodule, so clone recursively:

git clone --recursive https://github.com/fcoury/knuckles.git
cd knuckles
npm install
npm run build

npm run build runs Ergogen on ergogen/config.yaml and writes the PCBs, plates, outlines, and bottom tray STL. npm run debug does the same with Ergogen's debug output. npm run watch:build and npm run watch:debug rebuild whenever the YAML or scripts change.

Key spacing

The default is 18.5 mm center to center. That's the compact layout and the one that was ordered. 19.5 mm is also available:

npm run build -- --spacing 19.5

# Keep both layouts side by side
npm run debug -- --spacing 18.5 --output build/18.5
npm run debug -- --spacing 19.5 --output build/19.5

Plates, holes, the silkscreen artwork, and the bottom tray all follow the selected spacing. Run npm run build -- --help for all options. The gotchas cover how spacing interacts with the other scripts.

Full pipeline

The full pipeline also needs Docker. It runs KiCad 8, KiBot, and Freerouting in containers, pulling the images on first run.

./build.sh:

1. Cleans previous outputs.
2. Runs Ergogen to generate the unrouted board and plates.
3. Exports renders and Gerbers for the plates and unrouted board with KiBot.
4. Exports a DSN, autoroutes it with Freerouting, and imports the SES back into KiCad.
5. Runs KiBot again on the autorouted board.

Other entry points:

• ./rebuild.sh re-exports and autoroutes the boards already in pcbs/ without running Ergogen.
• npm run route autoroutes only knuckles_wireless. It prunes dead-end traces and tries up to three times. A route is accepted only if KiCad reports no unconnected items, no dangling tracks, and no DRC errors.
• ./watch.sh (macOS, needs fswatch) regenerates the PCB when the config changes and opens the result.

Manufacturing

Upload the KiBot ZIP from ergogen/output/gerbers/knuckles_wireless/ to JLCPCB. Manufacturing output comes only from pcbs/knuckles_wireless_autorouted.kicad_pcb. The KiBot configs (kibot/default.kibot.yaml, kibot/boards.kibot.yaml) are tuned for JLCPCB. The board uses a 0.25 mm copper-to-edge clearance for routed outlines.

Local builds and CI both route through scripts/autoroute.sh, with the same KiCad image, Freerouting 2.1.0 JAR, rules, and optimizer settings. Freerouting can still produce different trace geometry from run to run. That's why the pipeline checks connectivity and DRC instead of comparing files byte for byte.

Each board that gets ordered goes in its own dated folder under manufacturing/. Don't modify those files once they're archived.

CI

.github/workflows/build.yaml runs the full pipeline for both spacings. Each run uploads a knuckles-18.5mm and a knuckles-19.5mm artifact containing cases, Gerbers, images, outlines, and PCBs. npm test runs real builds of both layouts and checks spacing selection, the generated outputs, and rejection of invalid values.

Customizing

Everything starts in ergogen/config.yaml:

• Layout: the key matrix and thumb fan are under points.zones.* (spacing, splay, stagger).
• Switches: set meta.footprint and pick a preset (mx, choc_v1, choc_v2, or the low-profile reversible footprints).
• Wiring: column and row nets are assigned per zone. MCU pins are mapped in the mcu footprint section.
• Touchpad: the TPS43 adapter sits on top of the nice!nano and uses its VCC, GND, SDA, and SCL pins, so the PCB doesn't need its own touchpad footprint.
• Case: edit cases/knuckles_bottom_tray.jscad and the outlines/_bottom_case* outlines to change walls and cutouts.

KiCad project settings in pcbs/ are generated, so edit kicad/projects/knuckles_wireless.kicad_pro instead. The build copies it next to the board.

The silkscreen badge and wordmark are documented in artwork/knuckles/.

Repository layout

Gotchas

• --spacing overrides KNUCKLES_SPACING, which overrides the config default. The YAML is never rewritten. pcbs/build-info.json records which spacing was used.
• Changing spacing means you need matching plates and a matching case. Don't mix routed boards or Gerbers from different spacing builds.
• ./build.sh (KNUCKLES_SPACING=19.5 ./build.sh) always writes to the root output folders. Use npm run build -- --output if you want them kept apart.
• ./rebuild.sh routes whatever board is already in pcbs/ and keeps its spacing.
• ergogen/output/pcbs/ contains old snapshots that builds don't update.

License

MIT. See LICENSE.

Credits

• Ergogen and its community.
• Footprints from ceoloide (ergogen/footprints/ceoloide) and related authors.
• Freerouting for autorouting, KiBot and PCBDraw for renders and exports.