[family] quarter_turn_cam_latch: Southco E5-class quarter-turn cam latch

[BenchCAD]

Family

• Family: quarter_turn_cam_latch — cat:furniture-hardware
• Closes [family] quarter_turn_cam_latch #32

Reference (issue #32 — Southco E5)

Datasheet drawing	Part photo

Generated — benchmark views (what the model sees)

Extremes — smallest & largest sampled instances

How it's parameterized

Head (slotted tool-recess or plain knob) + double-D body (circle Ø + across-flats,
the E5 anti-rotation cutout) + flat cam arm clamping at the grip depth. 10 params;
grip is coupled to the housing length in refine() (cam clamps within the
housing); one feature (slotted).

Verification (every sampled instance — one non-degenerate solid)

difficulty	head_d	head_h	body_d	afl	body_l	grip	solids	valid	bbox (mm)
easy s0	27.27	5.27	22.02	19.51	29.07	14.87	1	yes	98×27×34
medium s0	25.82	6.58	16.55	14.2	41.15	35.17	1	yes	95×26×48
hard s0	26.37	6.43	15.35	13.13	59.48	52.02	1	yes	102×26×66
hard s1	28.61	11.89	19.01	15.19	18.36	6.13	1	yes	91×29×30
hard s2	28.62	7.94	22.58	17.91	60.3	15.55	1	yes	85×29×68

bench2 validate quarter_turn_cam_latch --seeds 5 → PASS.

Checklist

• bench2 validate passes locally (CI re-runs it)
• renders committed; matches the E5 drawing (head/double-D/cam) incl. extremes
• one family, only designs/quarter_turn_cam_latch/ (package files only)
• body has Closes #32; DCO-signed; sources cited, nothing fabricated

Sources used

• Southco E5 literature: head Ø28x5 / mini Ø22x12.2; double-D cutout 20.1 A/F / Ø22.5 (mini 14.1/16.3); housing 27.2 & long 45.5/58.2/68.2; cam 45/33; grip 4-42 (2 mm steps), long-housing table to 82.
• Cam width/thickness — proportion (stamped zinc cam).

Note: drawn latched as one solid; the M6 cam screw, spring washer stack, and
the DIN-key recess variants are not modelled (slot stands in for tool recess).

Codex review (gpt-5.6-sol): cam corrected to overall catalog length (axis-centred slot, dead intersect removed), afl/body pairing per the real cutouts, binding cam-reach check, grip in 2 mm steps.

[github-actions]

bench2 validate

quarter_turn_cam_latch

  ✓ family.json: keys + base_plane valid
  ✓ pieces: build(10 params) + PARAM_SPEC + check present
  ✓ PARAM_SPEC: 10 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, 1 solid(s) each
PASS — designs/quarter_turn_cam_latch

Previews: the previews artifact on this run.