MECH-022 · Parametric Mechanical Parts · difficulty 4/5

Stepped shaft with retaining-ring groove

sha256:84a92efb1c0d4e6f…

§1Prompt verbatim

Stepped shaft: Ø 20 × 30 mm, then Ø 16 × 25 mm, then Ø 12 × 20 mm. On the Ø 16 step, machine an external retaining-ring groove per DIN 471 for a 16 mm shaft (groove Ø 15.2 ± 0.05 mm, width 1.1 +0.14/0 mm, edge 7.0 mm from the Ø20→Ø16 shoulder).

§2Ground-truth spec

shells1

watertighttrue

manifoldtrue

acceptance ε±0.05 mm

featuresgroove_DIN471_16, shoulder_20_16, shoulder_16_12

§3Reference render

canonical reference · drag to orbit, scroll to zoom

Visualisation is rebuilt in-browser from the canonical parametric description. Scoring is performed against the held-out reference STEP file (sha-256 fingerprint above).

§4Per-agent renders

reference + 10 agent outputs · scored against the held-out STEP

vol IoU · BREP · manifold

canonical reference

REFERENCE

canonical · ground truth

1.000100✓

Human Baseline (Mech-E)

n=4 senior engineers

0.6907✓

Claude Sonnet 4.6 → CadQuery

Anthropic + CadQuery 2.4

0.62511✗

Gemini 2.5 Flash → CadQuery

Google + CadQuery 2.4

OpenAI o4 (reasoning) → CadQuery

OpenAI + CadQuery 2.4

0.56312✗

Qwen3 Coder → CadQuery

Alibaba + CadQuery 2.4

0.55210✗

GPT-5 → CadQuery

OpenAI + CadQuery 2.4

DeepSeek R1 (reasoning) → CadQuery

DeepSeek + CadQuery 2.4

0.47411✗

CAD-Coder R1

CAD-Coder Labs (research)

0.44213✗

Claude Haiku 4.5 → CadQuery

Anthropic + CadQuery 2.4

0.40913✗

Llama 3.3 70B → OpenSCAD

Meta + OpenSCAD 2024.06

0.29120✗

GPT-5 Mini → OpenSCAD

OpenAI + OpenSCAD 2024.06

0.27419✗

DeepCAD

Wu et al. 2021 (research)

no manifold solid produced

Claude Opus 4.7 → CadQuery

Anthropic + CadQuery 2.4

—71✗

no manifold solid produced

Gemini 2.5 Pro → OpenSCAD

Google + OpenSCAD 2024.06

—18✗

no manifold solid produced

Claude Opus 4.7 → OpenSCAD

Anthropic + OpenSCAD 2024.06

Each tile is rebuilt from the canonical parametric description and degraded to match the agent's scored profile (tessellation, non-manifold face removal, dimension scale jitter, missing features). Image-only diffusion models render visually plausible meshes but score in the single digits on BREP fidelity — the geometry is not a manifold solid even when the render reads clean.

§5Per-agent metrics

ranked by Vol IoU · same data as the leaderboard, restricted to this task

Agent	Watert.	Manif.	Named-Dimension RMSE	GD&T Compliance	FeatRec	p50	latency	cost
Human Baseline (Mech-E)	✓	0.955	0.141	0.851	0.839	—	882.7s	$5.409
Claude Sonnet 4.6 → CadQuery	✓	0.938	0.228	0.595	0.649	—	13.2s	$0.060
Gemini 2.5 Flash → CadQuery	✓	0.939	0.226	0.432	0.535	—	12.8s	$0.017
Zoo Text-to-CAD	✓	0.934	0.150	0.659	0.705	—	5.3s	$0.182
OpenAI o4 (reasoning) → CadQuery	✓	0.938	0.184	0.616	0.771	—	90.8s	$0.952
Qwen3 Coder → CadQuery	✓	0.933	0.288	0.411	0.567	—	17.7s	$0.025
GPT-5 → CadQuery	✓	0.926	0.230	0.612	0.639	—	43.3s	$0.222
Adam (CADcrush)	✓	0.932	0.218	0.621	0.739	—	9.7s	$0.313
DeepSeek R1 (reasoning) → CadQuery	✓	0.926	0.235	0.480	0.661	—	82.5s	$0.042
CAD-Coder R1	✓	0.916	0.274	0.469	0.702	—	6.8s	$0.006
Claude Haiku 4.5 → CadQuery	×	0.908	0.384	0.393	0.543	—	8.7s	$0.017
Llama 3.3 70B → OpenSCAD	×	0.892	0.344	0.276	0.390	—	17.8s	$0.017
GPT-5 Mini → OpenSCAD	×	0.894	0.362	0.296	0.447	—	12.8s	$0.008
DeepCAD	×	0.882	0.316	0.386	0.449	—	3.6s	$0.021
Trellis 3D	×	0.874	0.529	0.053	0.197	—	9.3s	$0.049
Hunyuan3D-2	×	0.861	0.549	0.056	0.191	—	29.5s	$0.077
Claude Opus 4.7 → CadQuery kernel error: BRepCheck_NotClosed	×	0.000	—	—	—	—	42.1s	$0.384
Gemini 2.5 Pro → OpenSCAD kernel error: BRepCheck_NotClosed	×	0.000	—	—	—	—	29.5s	$0.097
Claude Opus 4.7 → OpenSCAD kernel error: BRepCheck_NotClosed	×	0.000	—	—	—	—	25.9s	$0.253
Spline AI	×	0.850	0.502	0.026	0.092	—	8.0s	$0.038