[family] single_friction_bearing_universal_joint: DIN 808 EG friction-bearing universal joint

[sunzhenchuan007]

Family

• Family: single_friction_bearing_universal_joint
• Standard / type: DIN 808 EG — steel, single-jointed universal joint with friction bearing
• Closes [family-assembly] single_friction_bearing_universal_joint #61
• A three-body static assembly with two congruent yokes, equal B/K/V end treatment, and one orthogonal cross.

Reference (Issue #61 — JW Winco DIN 808 EG)

The official engineering drawing, product photograph, metric catalog table, and source links are recorded in #61. This PR implements only the single-jointed EG form; it does not include the double-jointed DG form.

Generated — benchmark views (what the model sees)

Generated — easy / medium / hard samples

Extremes — smallest & largest sampled instances

Distinct parts and assembly

preview_parts.png gives four views for each distinct part type. The congruent input/output yoke is shown once (quantity 2), the cross once (quantity 1), followed by assembly highlight views.

How it's parameterized

catalog_row selects exactly one of the 19 official JW Winco metric rows. refine() copies the full coupled row — d1, d2, s, l1, l3, and t — without interpolation or cross-row mixing.

Tier	Catalog selection	End treatment	Joint angle
easy	central rows	B	small angles
medium	broader rows	B / K	up to 45°
hard	all 19 rows, including MOQ-marked extremes	B / K / V	up to 45°

Both ends always use the same selected treatment:

• B: equal round bores
• K: equal round bores with DIN 6885-1 JS9 keyways; official b and t2 values are coupled to the bore
• V: equal square bores

The output yoke is a rigidly transformed instance of the same yoke geometry as the input. The static pose preserves centered, perpendicular trunnion axes while joint_angle varies from 0° to 45°.

First-version scope excludes DG, l2, l4, a second cross, unequal/inch bores, needle-bearing and stainless variants, shafts, and protective boots.

Components and assembly

build() returns a cq.Assembly with stable component names:

Assembly name	Part type	Quantity
input_yoke	yoke	1
output_yoke	congruent transformed yoke	1
cross	orthogonal cross	1

family.json declares "solids": 3; components[].quantity sums to 3 and matches the three Assembly entities. Each component is built independently.

No exploded sequence or assembly arrows are claimed because the reviewed public evidence does not dimension the omitted pins, sleeves, caps, or retainers.

Notes for review

NOTES.md records:

• the DIN/JW Winco symbol-to-parameter mapping;
• the 19-row coupling and l1 = 2*l3 relationship;
• the independent builders, stable Assembly names, and static transform convention;
• the distinction between published dimensions and deliberate proportion geometry;
• omitted, unsupported construction details and other simplifications.

Fork-eye, cross-arm, root-overlap, and internal-clearance dimensions not published in the reviewed sources are honestly labeled proportion rather than presented as DIN or manufacturer dimensions.

Verification

Check	Result
uv run bench2 validate single_friction_bearing_universal_joint	PASS
easy / medium / hard	4/4 seeds each sample, check, build, and execute cleanly
parameters	11 complete
geometry novelty	9/12 unique shapes (25% duplicate)
solids	3 non-degenerate solids in every sampled instance
exhaustive envelope audit	19 rows × 3 bore codes × 4 angles = 228 cases
component integrity	each component remains one non-degenerate solid
pairwise intersections	maximum volume = 0 for all three component pairs
minimum component volume	133.759930 mm³
Assembly identity	stable names verified in all 228 cases
Ruff	part.py and spec.py pass

Checklist

• uv run bench2 validate single_friction_bearing_universal_joint passes locally (CI re-runs it).
• All three standard previews were generated, inspected, and committed: preview.png, preview_views.png, and preview_extremes.png; the additional preview_parts.png was also inspected and committed.
• Multi-body metadata is consistent: "solids": 3, three stable Assembly entities, and component quantities summing to 3.
• Every PARAM_SPEC.source and every check() constraint cites the JW Winco tables or honestly says proportion.
• The PR touches only designs/single_friction_bearing_universal_joint/ and contains only allowed family package files.
• The commit is DCO-signed.
• AI-assisted: the human contributor reviewed the implementation, sources, constraints, validation output, and all preview images.

Sources used

• JW Winco DIN 808 product page
• JW Winco DIN 808 official PDF
• JW Winco DIN 6885-1 official keyway PDF
• Issue [family-assembly] single_friction_bearing_universal_joint #61 engineering drawing, product photograph, and metric-table attachments
• proportion for uncited fork-eye, cross-arm, root-overlap, and clearance geometry

Deliberate simplifications

• Static multi-body envelope only; no kinematic mates, RPM, torque, or performance claims.
• The published t +1 tolerance is not sampled; nominal table t defines the shaft-insertion envelope.
• H7/H10/JS9 tolerances are metadata, not tolerance samples.
• Unsupported sleeves, pins, caps, retainers, lubrication passages, blends, and chamfers are omitted rather than guessed.

[github-actions]

Welcome, and thanks for the family PR! Three things that answer most questions:

• No checks running? A maintainer must click Approve workflows once for your first PR — pending, not ignored.
• Red gate? The message tells you the fix: click Details, or read the bench2 validate report comment posted after each run. Reproduce locally with uv sync && uv run bench2 validate <family> (debug help).
• Scope: designs/<family>/ holds only the package files (reference drawings/photos go in the family issue), and the PR checklist must be fully ticked. Not done yet? Mark the PR as a Draft.

中文:红 ✗ 点 Details 或看 validate 报告评论;本地 uv run bench2 validate <family> 复现;参考图放 issue 不放 PR;没做完用 Draft。入门 → GETTING_STARTED.zh

[github-actions]

bench2 validate

single_friction_bearing_universal_joint

  ✓ family.json: keys + base_plane valid
  ✓ pieces: build(11 params) + PARAM_SPEC + check present
  ✓ PARAM_SPEC: 11 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: 9/12 unique shapes (25% duplicate)
  ✓ solids: every instance non-degenerate, 3 solid(s) each (declares solids=3)
PASS — designs/single_friction_bearing_universal_joint

Previews: the previews artifact on this run.