🔌 Keystone

📌 What

Parametric keystone jack socket module for integrating standard keystone connectors into HomeRacker panels. Provides the negative geometry (pocket + socket) that accepts any standard keystone module, plus optional snap-fit label plate slots for port identification.

Based on dimensions from the Parametric Keystone Connector by Paul Hatcher (Public Domain / CC0).

🤔 Why

Keystone jacks are the universal standard for structured cabling (Ethernet, HDMI, USB, coax, fiber). By providing a reusable pocket module, any HomeRacker panel can become a patch panel without reinventing the snap-fit geometry each time.

• Rotation support (0°, 90°, 180°, 270°) — mount jacks vertically or horizontally to trade off panel density vs. cable bend room.
• Snap-fit label system — printed label plates identify ports without adhesive labels that peel off, or labels that are baked into the panel and can’t be changed.
• Label above or below (label_position) — put the label slot on either side of the jack so stacked rows can tuck labels between them without covering the opening of the row above.
• Fit-tunable — additional_tolerance widens the socket cut for printers/filaments that run tighter or looser than the reference.

Where the dimensions come from

The socket profile is measured from Paul Hatcher’s CC0 Parametric Keystone Connector: that STL printed and fit a perfect range of real jacks (e.g. deleyCON CAT.7), so the distances were measured in the slicer and translated into parametric SCAD. The label dimensions instead derive from HomeRacker core constants (KS_LABEL_HEIGHT = BASE_UNIT, KS_LABEL_STRENGTH = BASE_STRENGTH, KS_LABEL_CHAMFER = TOLERANCE * 4) so labels stay on-system.

Out of scope

Only standard keystone jacks (the universal snap profile). No angled/recessed keystones, no blank filler inserts, and no shuttered/dust-cover variants — those exist en masse online. The module is a cutter (negative geometry); you bring your own panel body.

🔧 How

End-to-end workflow

1. Design a panel and cut keystone pockets into it with keystone_full() inside a diff("keystone") context (see Library Usage).
2. Print the panel. The socket is a tunnel through the panel; it may protrude behind a thin wall — that’s expected.
3. Snap the jack in from the back of the panel. The retention hooks grab it and the front face stays clean and flush.
4. Label (optional): print label_plate() parts separately and snap them into the front recess. Labels print face-down for a clean multicolor result (see Label system).

💡 Print a single-jack sample first. parts/keystone_sample.scad exists so you can print one pocket in minutes — verify your jacks seat correctly and tune additional_tolerance — before committing filament and hours to a full panel.

Try it in the Customizer

Open parts/keystone_sample.scad in OpenSCAD and use the Customizer panel.

Display Modes

Parameters

Geometry Backend (native vs BOSL2)

The socket, panel-side label recess, and label plate each ship two interchangeable geometry backends that produce the identical printable shape (verified by zero-volume boolean parity). Pick one via the geometry Customizer dropdown, or globally in code with the $ks_native special variable (true = native, false = BOSL2) — like $fn it propagates to all children, so set it once at the top of your file.

Both backends render the model’s solid identity colors (yellow socket, charcoal label plate). The only coloring difference is debug_colors: native geometry is a single fused mesh, so it cannot tint individual sections — use the bosl2 backend when you need per-section debug colors.

⚠ Disclaimer: the native geometry was fully AI-transpiled from the original BOSL2 code. It was print-tested with no noticeable difference from the BOSL2 version, but the bosl2 backend remains the authored source of truth — prefer it if in doubt. I personally only use the native geometry for really packed panels.

Why the speed gap: native geometry definitions are cached by OpenSCAD across identical copies, but a BOSL2 attachable/diff construction inside the geometry defeats that cache, and diff() re-evaluates its subtree multiple times per copy. On a populated panel this dominated render time, so native is the default.

Benchmark

Synthetic panel of 30 jacks (6×5) with label slots, rendered to STL (manifold backend, --render). Median of 3 runs:

≈ 6× faster on this panel, and the gap widens as you add more jacks. ¹Marginal cost is derived from the 1-jack vs 30-jack delta, isolating the per-copy geometry work the native cache eliminates.

_{Hardware: AMD Ryzen 9 7950X (16C/32T), 64 GB RAM, Windows. OpenSCAD 2026.06.12, manifold backend. OpenSCAD’s geometry render is effectively single-threaded, so wall-clock numbers are CPU-clock bound and reproduce closely across runs. Reproduce with _visual_test/ks_bench.scad (throwaway, not tracked) — see the decision record for the method.}

Label system design

The label system is an original HomeRacker design layered on top of the measured socket profile:

• Snap-fit retention with a minimal lip overlap — enough to hold the plate against shaking/vibration, not so much that it fights you.
• Generous top & bottom chamfers give you a fingernail purchase to pop a plate back out.
• Double-slit slot — not for style: it lets the whole part bridge cleanly so it prints support-free, and lets the label print face-down for an easy, clean multicolor result.
• Print-ready layout — label_plate_mode = "plate" lays the plate flat next to the panel so the Parametric Model Maker can drop it onto a MakerWorld build plate.

debug_colors = true on the bosl2 backend — panel body (white), socket sections (yellow), label recess (blue), label hooks (red/green).

Print & fit testing

additional_tolerance is the one knob you may need to touch. It is added only to the socket width and height, defaults to 0.0, and that default fits the reference jacks perfectly on the author’s printer. Because no two printers or filaments shrink alike, the single-jack sample exists to test the fit cheaply before printing a whole panel.

Two printed single-demo panels with CAT.7 jacks snapped in from the back. Left at additional_tolerance = 0.0 (perfect fit), right at 0.2 (a touch of wiggle).

• 0.0 — reference fit; works as-is for the author.
• 0.2 — a hair looser; still seats and holds fine.
• 1.0 — untested; likely too loose to retain a jack. Step up in small increments.

Library Usage

include <homeracker/models/keystone/lib/keystone.scad>

// Use in a diff("keystone") context to cut a keystone slot into a panel:
diff("keystone")
cuboid([50, 2, 50]) {
  align(FRONT, BOTTOM, inside=true)
    keystone_full(yrot=0, panel_depth=15, add_label_slots=true);
}

Key Modules

keystone_full() and keystone_demo_panel() accept label_plate_mode ("assembly" or "plate") and label_plate_gap (mm) to control label plate placement for build-plate layouts. They also accept label_position ("above" or "below") to mirror the label slot to either side of the jack.

Key Functions

📸 Catalog

Part	Preview
Keystone Sample
Label Below
Plate Mode (print-ready)
Debug Colors

To generate or refresh previews:

scadm export-png models/keystone/parts/keystone_sample.scad
scadm export-png models/keystone/parts/keystone_sample.scad -p models/keystone/parts/keystone_sample_below.json -P label_below --output models/keystone/parts/renders/keystone_sample_below.png
scadm export-png models/keystone/parts/keystone_sample.scad -D 'mode="single"' -D 'label_plate_mode="plate"' --output models/keystone/parts/renders/keystone_sample_plate_mode.png
scadm export-png models/keystone/parts/keystone_sample.scad -D 'mode="full"' -D 'debug_colors=true' -D '$ks_native=false' --output models/keystone/parts/renders/keystone_sample_debug.png

📚 References

• HomeRacker core — constants, supports, connectors
• Panel model — plain panels that can host keystone sockets
• Keystone socket & label design — decision record (provenance, label design, backend toggle)
• Parametric Keystone Connector — original dimension reference (CC0)

The HomeRacker-exclusive keystonepanel model is a real consumer: it lays out rows of jacks using get_effective_keystone_width() / get_effective_keystone_height() / get_label_attachable_height() and cuts them with keystone_full().