[family] metric plastic cable gland

[songmingqing36-lang]

Reference (re-embedded from issue #31)

Datasheet drawing	Product photo

Datasheet drawing	Product photo

Family

• Family: metric_plastic_cable_gland — cat:enclosure-hardware
• Closes [family] metric_plastic_cable_gland #31
• An assembled metric polyamide cable gland with a male connection thread, hexagonal body, fluted domed cap, cable passage, and an M40+ shoulder seal.

Reference (issue #31 — LAPP SKINTOP ST-M)

Datasheet drawing	Part photo

Generated — benchmark views (what the model sees)

Generated — easy / medium / hard samples

Extremes — smallest & largest sampled instances

How it's parameterized

size_index selects one complete LAPP SKINTOP ST-M catalog row from M12 through M63. refine() then copies that row's nominal thread diameter, wrench size, cap diameter A, thread length D, clamping range F, and O-ring state into the model without mixing dimensions between sizes.

tightened selects the published C minimum or C maximum for the same row, representing the fully compressed or relaxed cap position. The external geometry includes an Mx1.5 connection thread, six-flat wrench body, round domed cap with 12 longitudinal grip ribs, functional cable passage, and the M40/M50/M63 shoulder-seal band.

Ten parameters describe the family:

• size_index: coupled M12–M63 catalog row.
• thread_d: nominal EN 60423 metric connection diameter; pitch fixed at 1.5 mm.
• sw: body wrench size across flats.
• outer_dia_a: cap outside diameter A.
• overall_len: catalog C minimum or maximum selected by tightened.
• thread_len: male connection length D.
• clamp_min, clamp_max: catalog cable clamping range F.
• o_ring: M40+ NBR shoulder-seal feature.
• tightened: relaxed versus fully tightened cap position.

The molded thread crest, internal trapezoidal cap thread, elastomer insert, and grip-rib detail are simplified with explicit proportion rules where the manufacturer does not publish their internal geometry.

Verification (sampled instances — one non-degenerate solid)

difficulty	row	state	thread	SW	A	C	clamp F	O-ring	solids	valid	bbox (mm)
easy s0	M16	relaxed	16	19	21.1	34	4–10	0	1	yes	21.9×21.2×34
medium s0	M32	tightened	32	36	40.3	39	9–21	0	1	yes	41.6×40.3×39
hard s0	M63	tightened	63	66	73.9	59	34–45	1	1	yes	76.2×73.9×59
hard s1	M50	tightened	50	55	61.6	54	27–34	1	1	yes	63.5×61.6×54
hard s2	M63	relaxed	63	66	73.9	71	34–45	1	1	yes	76.2×73.9×71

uv run bench2 validate metric_plastic_cable_gland --seeds 4 → PASS (10 parameters complete; all eight catalog rows covered; difficulties distinct; every instance one non-degenerate solid).

Checklist

• uv run bench2 validate metric_plastic_cable_gland passes locally
• preview.png, preview_views.png, and preview_extremes.png generated and inspected
• all M12–M63 dimensions remain coupled to one DB53111000EN v17 catalog row
• single-solid family; family.json correctly omits a multi-body solids declaration
• every PARAM_SPEC.source and check() constraint cites a catalog/rule or honest proportion
• PR touches only designs/metric_plastic_cable_gland/
• commits are DCO-signed
• AI-assisted; human contributor reviewed every line and stands behind the constraints

Sources used

• LAPP SKINTOP ST-M official data sheet DB53111000EN v17 (20 June 2023), dimension table for M12x1.5 through M63x1.5.
• EN 60423 metric cable-gland connection sizes; pitch fixed at 1.5 mm for the selected range.
• Issue [family] metric_plastic_cable_gland #31 reference drawing and product photograph for the assembled hex-body / round-fluted-cap form.
• Internal trapezoidal thread, elastomer insert, crest shape, and grip-rib details: proportion, because separate molded dimensions are not published.

Data note: the M20 row has Cmin 34 mm and Cmax 37 mm, so its published compression travel is 3 mm. The implementation follows the v17 table directly where the issue's prose summary says 3.5 mm minimum.

---

Maintainer commits 5d8001f + 44e4efa: hex washer-face chamfers, thread-end + bore-mouth entry chamfers, full-height deeper grip strips; renders re-pinned to that head.

[github-actions]

bench2 validate

metric_plastic_cable_gland

  ✓ 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
  ✓ coverage: size_index reaches all 8 declared values (standard table fully covered)
  ✓ difficulty separation: difficulties produce distinct programs
  ✓ geometry novelty: 8/12 unique shapes (33% duplicate)
  ✓ solids: every instance non-degenerate, 1 solid(s) each
PASS — designs/metric_plastic_cable_gland

Previews: the previews artifact on this run.

[BenchCAD]

Maintainer note: I edited only the image urls in your description — they were pinned to your branch name, which gets deleted when this PR merges (taking every preview with it), so they now point at the same files pinned to 43c195c; no code changed and the images show exactly what they did before. / 【维护者说明】只改了描述里的图片链接:原先钉在分支名上,本 PR 合并后该分支会被删除、预览图会随之永久失效,现已改钉到 43c195c,指向的仍是同样的文件;代码没有任何改动,图片内容也完全一致。

[HaozheZhang6]

In top view the circle is internally tangent; not externally tangent

---

Thread-construction check (added 07-31): _ring_thread (part.py:14-24) builds the thread as concentric rectangular rings — consistent with the framework's ring-thread baseline (no helix on the pinned cadquery), so the construction itself is fine. Two details: the crest width is a fixed 0.45 mm instead of scaling with pitch (at P=1.5 that's a thin rib; use ~0.4·P), and int(height/pitch) plus the early break can leave the top of the band bare — derive the count from the covered span. The tangency finding above still stands.

[HaozheZhang6]

Maintainer pass, pushed as 5d8001f + 44e4efa on top of the review — five geometry updates, renders regenerated:

1. Top-view tangency (the review finding) — the dome base is now the hexagon's inscribed circle (sw/2, tangent to the flats from inside; it was outer_dia_a/2 and stood proud of the flats).
2. Stepped top entry — the cable entry is a counterbore stepping down to the clamp bore: two concentric circles in top view, as on the real gland.
3. Hex washer-face chamfers — both hex bands carry the z-direction chamfer on their top and bottom rims (previously only the vertical corner edges).
4. Entry chamfers on the bottom plane — 45° lead-in on the thread-end OD plus a cone at the bore mouth.
5. Grip strips full height, deeper — they stopped 11 % short at both ends; now aligned with the nut band and cut deeper (0.08→0.10·A).

Before (top row) vs after (bottom row) — iso · top view (tangency + step bore) · low-angle:

All four renders at 44e4efa:

Also in the PR body: render links re-pinned to this head, a ## Reference section re-embedding issue #31's drawing + photo, and preview_hard_zoom.png. bench2 validate passes. Still open from the review: the two thread-ring details (crest width vs pitch; top-of-band coverage).