# Extrusion corner bracket (simplified)

A simplified corner bracket for 20, 30 and 40 mm aluminium extrusions: two flat legs at a right angle, as tall as the
extrusion, without holes. For assemblies (envelope and position), not for the bracket's hole pattern.

## Geometry

The legs stand on the XY plane and rise along +Z by the height. One leg runs along +X, the other along +Y, each t
thick and centred on its axis, `leg` long from the origin; the small square outside the corner (−t/2..0, −t/2..0) is
open, as in the models.

| Series | Height | t | Leg, single | Leg, double |
|---|---|---|---|---|
| 2020 | 20 | 3 | 30 | 40 |
| 3030 | 30 | 4.5 | 45 | 60 |
| 4040 | 40 | 6 | 60 | 80 |

## Parameters

| Parameter | Meaning |
|---|---|
| `series` | `2020`, `3030`, `4040` |
| `variant` | `single` (shorter legs) or `double` (longer legs) |
| `material` | `unspecified` (no material assigned), `aluminum`, `steel` |

## Sources

These generic brackets name no maker and no standard covers them. **The geometry was measured from the published
reference models** below (each model's outline, a polygon read edge by edge at mid-height, and its height), and
every preset is checked against its own model: bounding box within 0.05 mm and volume within 2 %.

- **step.parts**, `corner_bracket_<series>_<variant>_simple` (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"`.

Simplifications (the models'): no holes, no slot keys, no gusset. The catalogue's gusseted brackets (a bar across one
leg, not joining the legs) and its joining plates and motor plates (all the same plain 50 × 30 × 3 block) are not
presets.

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