# T-slot extrusion accessories (simplified)

Simplified accessories for 20, 30 and 40 mm T-slot extrusions, for assemblies: end cap, slot cover strip, anchor
fastener and inside corner connector.

## Geometry

| `kind` | Shape |
|---|---|
| `end-cap` | a square plate the size of the profile, 3 mm thick (z = −1.5 to 1.5, centred), with one round plug peg 4 mm high standing on it at (+p, +p) |
| `cover-strip` | a flat strip along X, centred, `length` long |
| `anchor` | a block along X with a round pin through it along Z, both centred |
| `inside-corner` | an L of square bar in the XY plane, arms along +X and +Y from the origin, centred on z = 0, its outer corner square-cut |

| Series | Cap side / peg Ø / peg at p | Strip w × t | Anchor block (X × Y × Z) / pin Ø × l | Corner bar / arm |
|---|---|---|---|---|
| 20 | 20 / 3.6 / 5 | 5.6 × 2 | 14 × 7 × 7 / 5 × 16 | 7 / 20 |
| 30 | 30 / 5.4 / 7.5 | 8.4 × 2 | 21 × 10.5 × 10.5 / 7.5 × 24 | 10.5 / 30 |
| 40 | 40 / 7.2 / 10 | 11.2 × 2 | 28 × 14 × 14 / 10 × 32 | 14 / 40 |

## Parameters

| Parameter | Meaning |
|---|---|
| `kind` | `end-cap`, `cover-strip`, `anchor`, `inside-corner` |
| `series` | `20` (2020, 2040, ...), `30` (3030, 3060), `40` (4040, 4080) |
| `length` | cover strip length, mm |
| `material` | `unspecified` (no material assigned), `nylon` (PA6), `aluminum`, `steel` |

## Sources

No standard covers these generic accessories and they name no maker. **The geometry was measured from the published
reference models** below (every face read: plate, block and bar faces, the peg's and pin's cylinders), and every
preset is checked against its own models: bounding box within 0.05 mm and volume within 2 %.

- **step.parts**, `extrusion_<profile>_plastic_end_cap_simple`, `…_profile_cover_strip_simple`,
  `…_anchor_fastener_simple`, `…_inside_corner_connector_simple` for profiles 2020 to 4080
  (https://www.step.parts, repository https://github.com/earthtojake/step.parts, commit c6113328, `catalog/step/`):
  step.parts' own "analytic simplified" models, original project material under the repository's **MIT** licence
  (© 2026 earthtojake). They name no material, so the presets have `material = "unspecified"`.

The models of the 2040, 2060 and 2080 cover strips, anchors and corner connectors are the 2020 ones (3060: 3030;
4080: 4040), as the slot is the same: those entries share the series' preset. Their end caps are the square 20, 30
and 40 caps, not caps of those sections, and are not presets.

Simplifications (the models'): envelopes only. The cap has one off-centre peg instead of the slot clips, the anchor is
a block with a straight pin, the corner connector a plain L with no screws or teeth, the strip a flat bar.

Preset list: from the step.parts catalogue (MIT), see `library/NOTICE.md`.