KIN-002 · Kinematic Mechanisms · difficulty 5/5

Four-bar linkage, Grashof crank-rocker

sha256:611ac9802d310bff…

§1Prompt verbatim

Planar four-bar linkage with link lengths a=20, b=80, c=60, d=70 mm (Grashof crank-rocker). Build the four bodies and the three revolute joints — output one assembly STEP. Acceptance: simulate one full crank revolution; rocker angular sweep must be 70 ± 1° and no body interpenetrates at any point.

§2Ground-truth spec

shells4

watertighttrue

manifoldtrue

acceptance ε±0.05 mm

featuresrevolute_joint_x4

§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

0.67611✗

OpenAI o4 (reasoning) → CadQuery

OpenAI + CadQuery 2.4

Claude Opus 4.7 → CadQuery

Anthropic + CadQuery 2.4

0.53313✗

GPT-5 → CadQuery

OpenAI + CadQuery 2.4

0.42713✗

DeepSeek R1 (reasoning) → CadQuery

DeepSeek + CadQuery 2.4

0.39715✗

Claude Opus 4.7 → OpenSCAD

Anthropic + OpenSCAD 2024.06

0.3890✗

Llama 3.3 70B → OpenSCAD

Meta + OpenSCAD 2024.06

0.36315✗

Gemini 2.5 Flash → CadQuery

Google + CadQuery 2.4

0.33315✗

CAD-Coder R1

CAD-Coder Labs (research)

0.32917✗

Gemini 2.5 Pro → OpenSCAD

Google + OpenSCAD 2024.06

0.2980✗

Qwen3 Coder → CadQuery

Alibaba + CadQuery 2.4

0.27820✗

DeepCAD

Wu et al. 2021 (research)

0.26822✗

Claude Haiku 4.5 → CadQuery

Anthropic + CadQuery 2.4

0.22922✗

GPT-5 Mini → OpenSCAD

OpenAI + OpenSCAD 2024.06

no manifold solid produced

Claude Sonnet 4.6 → CadQuery

Anthropic + CadQuery 2.4

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.	FeatRec	Mating Clearance	ParamEdit	p50	latency	cost
Human Baseline (Mech-E)	✓	0.946	0.950	0.814	0.918	—	567.1s	$6.353
OpenAI o4 (reasoning) → CadQuery	✓	0.949	0.796	0.595	0.814	—	101.5s	$0.994
Adam (CADcrush)	✓	0.940	0.652	0.586	0.771	—	11.5s	$0.248
Zoo Text-to-CAD	✓	0.942	0.770	0.649	0.657	—	6.8s	$0.149
Claude Opus 4.7 → CadQuery	✓	0.925	0.698	0.571	0.738	—	49.4s	$0.278
GPT-5 → CadQuery	✓	0.914	0.675	0.583	0.763	—	30.9s	$0.215
DeepSeek R1 (reasoning) → CadQuery	×	0.908	0.651	0.579	0.721	—	102.3s	$0.034
Claude Opus 4.7 → OpenSCAD	×	0.911	0.580	0.550	0.562	—	38.6s	$0.274
Llama 3.3 70B → OpenSCAD	×	0.905	0.445	0.364	0.420	—	17.8s	$0.021
Gemini 2.5 Flash → CadQuery	×	0.898	0.603	0.511	0.657	—	13.2s	$0.017
CAD-Coder R1	×	0.899	0.612	0.511	0.594	—	5.6s	$0.004
Gemini 2.5 Pro → OpenSCAD	×	0.895	0.480	0.473	0.574	—	34.7s	$0.081
Qwen3 Coder → CadQuery	×	0.892	0.642	0.465	0.682	—	13.9s	$0.035
DeepCAD	×	0.889	0.465	0.387	0.278	—	4.8s	$0.019
Claude Haiku 4.5 → CadQuery	×	0.887	0.503	0.365	0.537	—	7.5s	$0.023
GPT-5 Mini → OpenSCAD	×	0.877	0.387	0.351	0.440	—	15.1s	$0.010
Trellis 3D	×	0.850	0.207	0.095	0.056	—	9.8s	$0.040
Spline AI	×	0.850	0.094	0.050	0.044	—	10.1s	$0.045
Claude Sonnet 4.6 → CadQuery kernel error: BRepCheck_NotClosed	×	0.000	—	—	—	—	21.1s	$0.063
Hunyuan3D-2	×	0.850	0.212	0.087	0.048	—	34.0s	$0.057