Tenting Legs & LED Diffuser

Two parts that are not needed for a working keyboard, but that most builders choose to add. Both are in the PolyKybd hardware repo under parts/.

Tenting legs

The legs attach under each half and tilt it towards you. Worth printing if you chose the stepped keycap stem profile, which is designed around the keyboard sitting at 5 degrees or more.

Part	File
Legs, 8 per plate	parts/export/legs/legs_r2_8p.stl

One plate is the whole set: eight legs in four mirrored pairs, 119 × 39 × 3.8 mm, so a single print does both halves.

The source is parts/legs/legs.scad; re-export it with parts/build_parts.sh legs.

LED diffuser frame

Each key has an LED behind it, shining through a half-round hole in the plate. Left bare, the light looks like a bright point rather than an even glow. The diffuser is a small light pipe that clips into that hole and spreads it.

The current generation is a one-piece frame: all 36 diffusers per half, held at their exact plate positions and rotations by a web that runs underneath the plate, through the solid material between the switch openings. So you fit one part per half instead of placing 36 loose pieces.

Part	File
Frame, left half	parts/export/diffuser/diffuser_frame_left.stl
Frame, right half	parts/export/diffuser/diffuser_frame_right.stl
Four copies stacked on a sprue	..._left_4x.stl / ..._right_4x.stl

Caution

Fitting the frame means using a different spacer: parts/export/case/spacer_diffuser_frame.stl instead of the plain spacer.stl, because the plain one has nowhere for the frame’s web to go. It is notched on both faces, so the one part serves either half — see Case & Spacer.

Print it in resin (SLA). It is a thin, delicate part, and the web is deliberately close to the minimum wall a print service will accept.

The _4x files stack four copies on top of each other, joined by a sprue so that a print service counts one part. The slicer still needs supports between the copies. Cut the pins off before fitting.

Fitting the frame

Fit the frame into the plate before anything else is done with the plate, and before the plate goes onto the spacer. The slide needs the space under the plate.

1. Hold the frame under the plate so that each diffuser goes up through its own switch opening.
2. Slide the frame about 5.5mm, so that each diffuser moves out of the switch opening and into the half-round LED hole next to it, until every diffuser sits in its half-round.

The caps on the top and bottom hold the plate between them, and the switches stop the frame from sliding back once they are in, so no glue is needed.

Changing the plate

The frame is generated from the plate PCB (poly_kybd/poly_kybd_split72_plate_<side>.kicad_pcb) by parts/diffuser/gen_diffuser_frame.py.

So if you change the plate, regenerate it rather than edit the model by hand:

parts/diffuser/build_frame.sh          # regenerate from the PCB, export, verify
parts/diffuser/build_frame.sh --check  # verify the committed meshes only

The verify step runs parts/diffuser/check_frame.py, which checks watertightness, minimum wall thickness, left/right symmetry, the fit in the plate and clearance against the spacer.

The older diffuser

Earlier builds used 76 loose light pipes (parts/export/diffuser/diff_v2.stl), clipped in one at a time. They still print, but the frame is much easier to fit.