MECH-014 · Parametric Mechanical Parts · difficulty 3/5

L-bracket with M6 + slotted hole

sha256:1f3a5e90c44b2210…

§1Prompt verbatim

Right-angle L-bracket, leg lengths 60 mm and 40 mm, thickness 5 mm. Through-hole Ø 6.6 mm with 1.5 × 45° chamfer on the long leg, centred 30 mm from the bend. Slotted hole 8 × 16 mm on the short leg, centred 20 mm from the bend, slot major axis parallel to the bend. Position tolerance ±0.1 mm. Output STEP AP242.

§2Ground-truth spec

shells1

genus2

watertighttrue

manifoldtrue

acceptance ε±0.1 mm

featuresbend_R5, thru_hole_M6_clearance, chamfer_1.5x45, slot_8x16

§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

0.7637✓

OpenAI o4 (reasoning) → CadQuery

OpenAI + CadQuery 2.4

0.68111✓

GPT-5 → CadQuery

OpenAI + CadQuery 2.4

Gemini 2.5 Flash → CadQuery

Google + CadQuery 2.4

Claude Opus 4.7 → OpenSCAD

Anthropic + OpenSCAD 2024.06

0.5600✗

Claude Haiku 4.5 → CadQuery

Anthropic + CadQuery 2.4

0.51310✗

CAD-Coder R1

CAD-Coder Labs (research)

0.50111✗

Claude Opus 4.7 → CadQuery

Anthropic + CadQuery 2.4

0.50014✗

Gemini 2.5 Pro → OpenSCAD

Google + OpenSCAD 2024.06

0.4550✗

DeepSeek R1 (reasoning) → CadQuery

DeepSeek + CadQuery 2.4

0.44410✗

Qwen3 Coder → CadQuery

Alibaba + CadQuery 2.4

0.42711✗

Llama 3.3 70B → OpenSCAD

Meta + OpenSCAD 2024.06

0.39713✗

GPT-5 Mini → OpenSCAD

OpenAI + OpenSCAD 2024.06

0.39115✗

DeepCAD

Wu et al. 2021 (research)

no manifold solid produced

Claude Sonnet 4.6 → CadQuery

Anthropic + CadQuery 2.4

—66✗

no manifold solid produced

Hunyuan3D-2

Tencent

—5✗

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	P@1	p50	latency	cost
Human Baseline (Mech-E)	✓	0.960	0.129	0.829	0.943	1.000	—	769.7s	$5.218
OpenAI o4 (reasoning) → CadQuery	✓	0.954	0.248	0.693	0.785	0.000	—	86.5s	$1.319
GPT-5 → CadQuery	✓	0.949	0.205	0.589	0.630	0.000	—	51.2s	$0.179
Zoo Text-to-CAD	✓	0.939	0.140	0.637	0.709	0.000	—	4.9s	$0.170
Gemini 2.5 Flash → CadQuery	✓	0.944	0.290	0.440	0.535	0.000	—	12.2s	$0.023
Adam (CADcrush)	✓	0.941	0.186	0.610	0.703	0.000	—	9.8s	$0.323
Claude Opus 4.7 → OpenSCAD	✓	0.938	0.269	0.461	0.583	0.000	—	23.3s	$0.319
Claude Haiku 4.5 → CadQuery	✓	0.929	0.362	0.369	0.483	0.000	—	9.7s	$0.017
CAD-Coder R1	✓	0.928	0.316	0.424	0.636	0.000	—	7.0s	$0.005
Claude Opus 4.7 → CadQuery	✓	0.927	0.243	0.622	0.770	0.000	—	29.4s	$0.366
Gemini 2.5 Pro → OpenSCAD	✓	0.920	0.320	0.403	0.531	0.000	—	26.0s	$0.095
DeepSeek R1 (reasoning) → CadQuery	✓	0.919	0.284	0.506	0.632	0.000	—	89.9s	$0.043
Qwen3 Coder → CadQuery	✓	0.914	0.254	0.407	0.628	0.000	—	14.2s	$0.029
Llama 3.3 70B → OpenSCAD	×	0.907	0.374	0.281	0.444	0.000	—	18.0s	$0.018
GPT-5 Mini → OpenSCAD	×	0.913	0.316	0.287	0.408	0.000	—	17.1s	$0.011
DeepCAD	×	0.892	0.303	0.345	0.487	0.000	—	3.4s	$0.018
Trellis 3D	×	0.881	0.558	0.054	0.213	0.000	—	13.3s	$0.047
Spline AI	×	0.850	0.579	0.027	0.085	0.000	—	8.8s	$0.044
Claude Sonnet 4.6 → CadQuery kernel error: BRepCheck_NotClosed	×	0.000	—	—	—	0.000	—	15.5s	$0.062
Hunyuan3D-2 kernel error: BRepCheck_NotClosed	×	0.000	—	—	—	0.000	—	40.4s	$0.078