# C channel (light, square corners)

A light C (U) channel of constant thickness with square corners, at any width, height, thickness and length.

## Geometry

Web `width` along X at the bottom, flanges `height` along Y (overall), web and flanges `thickness` thick, centred on
the origin and extruded along +Z by `length`; the opening faces +Y. Section area = width × height − (width − 2t) ×
(height − t).

## Parameters

| Parameter | Meaning |
|---|---|
| `width` | overall width (web), mm |
| `height` | overall height (flanges), mm |
| `thickness` | web and flange thickness, mm |
| `length` | mm |
| `material` | `unspecified` (no material assigned), `aluminum`, `steel`, `stainless-304` |

## Sources

No standard covers these light channels (EN 755-9 and DIN 9714 give tolerances only; DIN 1026 channels are tapered)
and they name no maker. **The presets' geometry was measured from the published reference models** below: each
model's mid-length section (overall width and height, web and flange thickness; constant, square corners), and every
preset is checked against its own model: bounding box within 0.05 mm (0.5 % over 100 mm), volume within 2 %, section
area within 2 % and section outline within 0.1 mm.

| Channel | Thickness |
|---|---|
| 20 × 10 | 1.5 |
| 30 × 15 | 1.5 |
| 40 × 20 | 2.0 |

- **step.parts**, `c_channel_size<w>x<h>_l<length>` (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'): square corners inside and out.

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