sheet_hem
Fold a 180-degree hem back on itself to stiffen a free edge and bury the sharp cut line, producing safe-to-handle sheet-metal parts with closed or open styles.
Instructions
Fold a hem back on itself — the 180-degree return that stiffens a free edge and buries the sharp cut line so the part is safe to handle.
kind: 'closed' (inside radius t/2, gap t) or 'open' (radius t, gap 2t). radius_mm / gap_mm: override the style directly; the gap between the returned leg and the parent is exactly 2R, so gap wins as radius = gap/2.
length_mm is ALWAYS the return leg measured from the end of the bend: a 180-degree bend has no virtual apex to dimension to — the outside surfaces are parallel and never meet — so an 'outer' dimension would be infinite. For the same reason a hem reports a bend allowance but no bend deduction, and sheet_check screens it as a two-hit hem (bend, then flatten in a hemming die) exempt from the air-bend radius and flange rules. A teardrop hem wraps past 180 degrees and is out of scope.
Returns the same dict sheet_flange does, plus {hem_kind, gap_mm}.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| edge | Yes | ||
| kind | No | closed | |
| name | No | SheetHem | |
| gap_mm | No | ||
| handle | Yes | ||
| width_mm | No | ||
| direction | No | up | |
| length_mm | Yes | ||
| offset_mm | No | ||
| radius_mm | No | ||
| feature_name | No |