ASM-008 · Assembly & Mating · difficulty 5/5

Spline shaft + hub (DIN 5480 W25×1.25×18)

sha256:82bd03c0ef4a1100…

§1Prompt verbatim

Involute spline pair per DIN 5480 W 25 × 1.25 × 18: shaft and hub, 18 teeth, module 1.25, pressure angle 30°. Engagement length 22 mm. Resultant assembled clearance 0.04–0.10 mm normal to flank. Output one assembly STEP.

§2Ground-truth spec

shells2

watertighttrue

manifoldtrue

acceptance ε±0.01 mm

featuresspline_18T_m1.25

clearance[0.04, 0.1] mm

§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

0.72111✓

OpenAI o4 (reasoning) → CadQuery

OpenAI + CadQuery 2.4

Claude Opus 4.7 → OpenSCAD

Anthropic + OpenSCAD 2024.06

0.4800✗

Claude Opus 4.7 → CadQuery

Anthropic + CadQuery 2.4

0.47915✗

Claude Sonnet 4.6 → CadQuery

Anthropic + CadQuery 2.4

0.47813✗

DeepSeek R1 (reasoning) → CadQuery

DeepSeek + CadQuery 2.4

0.40514✗

CAD-Coder R1

CAD-Coder Labs (research)

0.38216✗

Claude Haiku 4.5 → CadQuery

Anthropic + CadQuery 2.4

0.34017✗

Qwen3 Coder → CadQuery

Alibaba + CadQuery 2.4

0.33415✗

Gemini 2.5 Flash → CadQuery

Google + CadQuery 2.4

0.29818✗

Llama 3.3 70B → OpenSCAD

Meta + OpenSCAD 2024.06

0.28919✗

GPT-5 Mini → OpenSCAD

OpenAI + OpenSCAD 2024.06

0.26219✗

DeepCAD

Wu et al. 2021 (research)

no manifold solid produced

GPT-5 → CadQuery

OpenAI + CadQuery 2.4

—66✗

no manifold solid produced

Gemini 2.5 Pro → OpenSCAD

Google + OpenSCAD 2024.06

no manifold solid produced

Spline AI

Spline.design

—2✗

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	Fit-Class Compliance	p50	latency	cost
Human Baseline (Mech-E)	✓	0.961	0.942	0.926	0.852	—	766.6s	$7.138
OpenAI o4 (reasoning) → CadQuery	✓	0.958	0.771	0.681	0.507	—	81.0s	$1.287
Zoo Text-to-CAD	✓	0.943	0.700	0.681	0.502	—	6.8s	$0.149
Adam (CADcrush)	✓	0.932	0.646	0.683	0.506	—	7.6s	$0.282
Claude Opus 4.7 → OpenSCAD	✓	0.922	0.540	0.501	0.240	—	40.2s	$0.315
Claude Opus 4.7 → CadQuery	✓	0.918	0.789	0.624	0.444	—	36.4s	$0.325
Claude Sonnet 4.6 → CadQuery	✓	0.927	0.668	0.631	0.367	—	16.0s	$0.073
DeepSeek R1 (reasoning) → CadQuery	×	0.909	0.678	0.541	0.278	—	84.1s	$0.042
CAD-Coder R1	×	0.904	0.660	0.541	0.250	—	6.3s	$0.005
Claude Haiku 4.5 → CadQuery	×	0.902	0.486	0.408	0.164	—	7.1s	$0.016
Qwen3 Coder → CadQuery	×	0.900	0.586	0.527	0.246	—	19.9s	$0.032
Gemini 2.5 Flash → CadQuery	×	0.896	0.557	0.475	0.252	—	9.0s	$0.024
Llama 3.3 70B → OpenSCAD	×	0.894	0.447	0.388	0.104	—	25.9s	$0.016
GPT-5 Mini → OpenSCAD	×	0.893	0.393	0.371	0.115	—	11.8s	$0.011
DeepCAD	×	0.875	0.497	0.387	0.164	—	3.9s	$0.019
Hunyuan3D-2	×	0.852	0.207	0.098	0.005	—	37.5s	$0.074
GPT-5 → CadQuery kernel error: BRepCheck_NotClosed	×	0.000	—	—	—	—	32.1s	$0.177
Gemini 2.5 Pro → OpenSCAD kernel error: BRepCheck_NotClosed	×	0.000	—	—	—	—	28.1s	$0.107
Trellis 3D	×	0.850	0.210	0.098	0.005	—	12.3s	$0.046
Spline AI kernel error: BRepCheck_NotClosed	×	0.000	—	—	—	—	5.7s	$0.047