[family-assembly] truss_half_coupler_hook: rigging half coupler / hook clamp

[BenchCAD]

Family

• Family: truss_half_coupler_hook — cat:av-rigging — assembly (solids=6)
• Closes [family-assembly] truss_half_coupler_hook #29

Reference (re-embedded from issue #29 — Doughty T57000/T57200)

Dimensioned drawing	Product photo

Renders (regenerated at this PR's head)

How it's parameterized — assembly

Per review: the coupler is modelled as the six parts it is assembled from —
hinged lower/upper shell around the Ø48-51 barrel, hinge pin, swivel closing
bolt (pivot eye + shank + ring thread), its pivot pin, and a DIN 315-style wing
nut whose internal thread rings sit on the same z-grid as the bolt rings,
offset half a pitch — engaged and measurably non-intersecting. Every mate is
contact-or-clearance (pins 0.15 radial, bolt-slot 0.6 a side, split plane 0.6 a
side, nut 0.3 over the lug). Same 8 sampled params as before (width 30-50 and
base drop 40-55 remain the per-model axes; stud still toggles the hook-clamp
variant); the bolt/nut/pin hardware derives from hang_d (M12/M10) as catalog
constants — see NOTES.md.

Verification (every sampled instance — six separate solids, zero pairwise intersection)

difficulty	bore_d	wall_t	body_w	base_drop	hang_d	solids	max pair overlap (mm³)	bbox (mm)
easy s0	48.37	6.34	48.24	53.08	13.0	6	0.00	126×48×115
easy s1	49.54	6.9	45.72	54.74	12.71	6	0.00	127×46×115
medium s0	49.91	5.08	30.82	40.25	12.78	6	0.00	124×31×136
medium s1	49.54	7.8	32.88	54.23	11.56	6	0.00	123×33×114
hard s0	49.91	5.35	30.86	40.25	13.24	6	0.00	127×31×138
hard s1	49.54	8.75	33.03	54.23	11.77	6	0.00	126×33×116

bench2 validate truss_half_coupler_hook → PASS, including
solids: every instance non-degenerate, 6 solid(s) each (declares solids=6).
Pairwise intersection measured directly (OCC common op) on both variants — all
0.00 mm³, including the interleaved bolt/nut thread rings.

Checklist

• uv run bench2 validate truss_half_coupler_hook passes locally (CI re-runs it)
• I ran uv run bench2 preview, looked at every image, and committed all four renders; the part matches the issue's reference drawing across all tiers, and both extremes are sane
• Multi-body part: family.json declares "solids": 6; per-part render committed and embedded above
• Every PARAM_SPEC.source and every check() constraint cites a real rule/table, or honestly says "proportion" — nothing fabricated
• PR touches only designs/truss_half_coupler_hook/, and only the package files
• Commits are DCO-signed
• (AI-assisted) I reviewed every line and stand behind the constraints

Sources used

• Doughty T57000/T57010/T58080/T58100/T57200 datasheets: Ø48-51 bore, widths 30-51, tube-centre→base 40-55, eye Ø12.7 (M12) / M10 option, hook-clamp M12x50 stud 34 proud; drawing dims 107 across / 116 tall / pins at 55.
• DIN 315 (wing nut proportions, shape anchor) and ISO 261 coarse pitch for the closing bolt — hardware constants derived from hang_d, documented in NOTES.md.

[github-actions]

bench2 validate

truss_half_coupler_hook

  ✓ family.json: keys + base_plane valid
  ✓ pieces: build(8 params) + PARAM_SPEC + check present
  ✓ PARAM_SPEC: 8 params, all entries complete
  ✓ easy: 4/4 seeds sample+check+build+execute clean
  ✓ medium: 4/4 seeds sample+check+build+execute clean
  ✓ hard: 4/4 seeds sample+check+build+execute clean
  ✓ difficulty separation: difficulties produce distinct programs
  ✓ geometry novelty: 12/12 unique shapes (0% duplicate)
  ✓ solids: every instance non-degenerate, 6 solid(s) each (declares solids=6)
PASS — designs/truss_half_coupler_hook

Previews: the previews artifact on this run.