automech

name	automech
description	AI-driven mechanical engineering pipeline for autonomous CAD generation. Use when designing FDM-printable parts (brackets, mounts, enclosures), mechanical assemblies, or running structural/acoustic simulations. Handles LLM-driven procedural CAD generation via @jscad/modeling with automated manufacturing validation.

Automech — AI-Driven Mechanical Engineering Pipeline

What This Pipeline Does

Automech is a deterministic multi-agent pipeline that converts natural language descriptions into validated 3D-printable STL files. It uses DeepSeek for the LLM layer and @jscad/modeling for procedural CAD geometry.

Architecture: Architect (constraint parsing) → Draftsman (code generation) → Sandbox (execution) → Physicist (simulation) → Machinist (printability validation). The pipeline iterates up to 5 times, feeding validation flags from later nodes back to the Draftsman for correction.

How to Invoke

All commands run from the project root.

npm run dev -- design "<prompt>"

Full pipeline: parses the prompt into constraints, generates JSCAD code, executes it in a sandbox, validates physics and manufacturability, outputs STL.

npm run dev -- design "Build a mounting bracket for a 5mm rod with two M3 bolt holes, use PA-CF, 50x40x30mm"

Other commands (stubs)

• npm run dev -- simulate <stl> — Not yet implemented
• npm run dev -- validate <stl> — Not yet implemented
• npm run dev -- iterate <design-id> — Not yet implemented

Key Environment

• DEEPSEEK_API_KEY must be set in .env
• The pipeline runs locally (no Docker required; Docker sandbox is optional, auto-fallback)

When to Use This Skill

Load this skill when the user:

• Asks to design a 3D-printable mechanical part
• Requests a CAD model from a text description
• Wants to iterate on a part using physical test data
• Needs manufacturing validation (overhangs, wall thickness, build volume)
• Asks about mechanical snap-fits, bolt patterns, or thermal insert geometries

Supported Materials

ID	Material	Tensile Strength	Max Strain	Max Overhang	Min Wall	Nozzle	Bed	Build Plate
PLA	Standard PLA	50 MPa	3%	55°	0.8mm	210°C	60°C	textured_pei
PETG	PETG (default)	48 MPa	5%	50°	1.0mm	245°C	80°C	textured_pei
PA-CF	Carbon-fiber nylon	110 MPa	1.5%	40°	1.2mm	290°C	90°C	engineering
TPU	Flexible TPU	35 MPa	60%	35°	1.2mm	235°C	40°C	smooth_pei

Material Shrinkage Compensation

Each material has shrinkage factors (shrinkageXY, shrinkageZ) and a holeOffset applied at CAD generation time — not at slicer time. This ensures internal tolerances remain accurate.

Material	Shrinkage XY	Shrinkage Z	Hole Offset
PLA	0.3%	0.5%	0.10mm
PETG	0.4%	0.6%	0.15mm
PA-CF	0.2%	0.3%	0.05mm
TPU	0.6%	0.8%	0.20mm

Clearance Profiles

Clearances (in mm) for press-fit, sliding-fit, loose-fit, and bearing-fit per material:

Profile	pressFit	slidingFit	looseFit	bearingFit
pla	0.04	0.15	0.30	0.06
petg	0.08	0.25	0.50	0.12
pa-cf	0.03	0.12	0.25	0.05
tpu	0.15	0.35	0.60	0.20
standard (fallback)	0.05	0.20	0.40	0.08

Hardware Registry (Available Fasteners)

Key	Type	Thread	Clearance Radius	Head/Insert Details
M3_SOCKET_CAP	bolt	M3	1.65mm	head radius 2.85mm, depth 3.0mm
M3_HEAT_SET_SHORT	heat_set_insert	M3	2.0mm	depth 4.0mm, taper 4.0°
M3_HEAT_SET_LONG	heat_set_insert	M3	2.0mm	depth 6.0mm, taper 4.0°
M3_NUT	nut	M3	3.3mm	—
M4_SOCKET_CAP	bolt	M4	2.2mm	head radius 3.65mm, depth 4.0mm
M4_HEAT_SET_SHORT	heat_set_insert	M4	2.7mm	depth 5.0mm, taper 4.0°
M5_SOCKET_CAP	bolt	M5	2.7mm	head radius 4.35mm, depth 5.0mm
M5_HEAT_SET_SHORT	heat_set_insert	M5	3.3mm	depth 5.5mm, taper 4.0°

Snap-Fit Mechanics

Snap-fits use the cantilever beam deflection formula to compute safe beam length:

ε = (3 · y · t) / (2 · L²)
→ L = √((3 · y · t) / (2 · ε_max))

Where y = deflection depth (hook undercut), t = beam thickness, L = beam length, ε_max = material max strain. A 10% safety factor is automatically added for FDM layer-line weaknesses. The generateCantileverClip() function in src/geometry/snapfit.ts produces the full JSCAD geometry.

Pipeline Nodes

Node	File	Role
Architect	src/nodes/architect.ts	Parses natural language into typed constraints (material, bounding box, fasteners, assembly type). Returns clarificationNeeded[] if dimensions are missing instead of hallucinating.
Draftsman	src/nodes/draftsman.ts	Generates procedural CAD code using @jscad/modeling. Must export a design() function returning a Geom3 object. No file I/O or network — pure geometry only. Receives failure flags from prior iterations as feedback.
Physicist	src/nodes/physicist.ts	Runs deterministic simulation (stub: currently always passes). Translates simulation failures into specific geometric directives (e.g., "Increase wall thickness at [X,Y,Z]").
Machinist	src/nodes/machinist.ts	Validates overhangs (via STL face normal analysis), wall thickness, build volume (256×256×256mm Bambu P2S limit), and runs headless slicer checks if available.
Technician	src/nodes/technician.ts	Accepts physical bench-test data (EmpiricalTestEvent) and back-propagates calibration deltas (shrinkage, hole offset) into the material profile registry. Computes constraint updates for acoustic, impedance, and kinetic test failures.
Sandbox Executor	src/sandbox/executor.ts	Runs Draftsman code in a Docker container (no network, 512MB RAM, 1 CPU, 15s timeout) with automatic local Node.js fallback if Docker is unavailable.

Interpretation of Results

• completed: STL outputted to /tmp/automech_runs/<runId>/output.stl
• blocked: Architect needs clarification — show the user the clarificationNeeded questions
• max_iterations (5 iterations exhausted): Show the errors — the first few flags are the most actionable for re-prompting

Constraints the Agent Should Enforce

1. Always specify dimensions in the prompt (bounding box [x, y, z] in mm)
2. Always specify the material (defaults to PETG if omitted by the user)
3. For bolted assemblies, specify which fasteners from the Hardware Registry to use
4. For snap-fit designs, material maxStrain governs beam length — PA-CF needs much longer beams than TPU
5. The Bambu Lab P2S build volume is 256×256×256mm — warn if user exceeds this
6. If a design requires wall thickness below the material's minWallThickness, flag it
7. If overhangs exceed the material's maxOverhangDeg, flag it
8. Never hallucinate fastener dimensions — always reference the Hardware Registry above