Cadquery Part

CadQuery part — functional geometry only

Purpose

Model one manufacturable component's functional solid: primary shape, structural voids (shells, pockets), and mating interface geometry (bores, spigots, slots, snap ledges) — so it assembles correctly. This pass is not cosmetic and not full DFM.

What this pass is NOT

Do not add in this pass (other skills own these):

A functional bracket may have a mounting bore (interface diameter) here; the clearance + counterbore for an M6 cap screw come in DFM.

Authoritative rules

Follow cad-generation.txt — Critical Pitfalls, Boolean Rules, Geometry Constraints, Mechanical Interfaces (model the interface shape, not full fastener spec).

Required file shape

"""<function_name> — <one-line role>. Origin: <part-local origin rule>."""
import cadquery as cq
import math
from common import (
    HOUSING_W, M3_BORE_DIA,  # every shared dim used
)

def build_<function_name>() -> cq.Workplane:
    # ---- functional geometry only ----
    ...
    return <part_name>

result = build_<function_name>()

• Path: parts/<function_name>.py
• Import shared dimensions from common.py — never duplicate HOUSING_W, mate PCDs, or partner bore diameters.
• Part-local origin documented in module docstring (e.g. "center of footprint, Z=0 on bottom face").

Inputs from orchestrator

• Function name, file path, manufacturing process guess
• Envelope + MATE_* constants from common.py
• Per-mate: what this part provides (socket, spigot, clearance bore, weld face, snap ledge)

Build order (mandatory)

1. Parameters — only dims not already in common.py.
2. Primary body — one main extrude, revolve, or .box() / .cylinder().
3. Structural voids — .shell(), pockets that define wall thickness (functional, not cosmetic).
4. Interface features — one single-extrusion tool per cut/union:
   • Bearing bores, shaft journals, keyways, drip-tray pockets, snap ledges
   • Pilot or clearance diameter only if it is the functional interface (e.g. bearing pocket Ø); thread/clearance pairs wait for DFM
5. No edge treatments — no .fillet() / .chamfer() except a functional shaft lead-in under 0.5 mm if required for assembly simulation
6. return the workplane from build_*(); result = build_*() at module level

Design realism (functional tier)

Apply what the function requires — not full cosmetics:

• Housings: hollow via .shell(-WALL_T) on simple faces — not solid blocks
• Shafts: bearing journal steps, keyway slot if driven
• Brackets: outline + mounting bore locations (use MATE_* positions from common.py)
• Plates: hole positions via pushPoints or construction rect + .vertices() — diameters may be finalized in DFM

Skip ribs, gussets, and fillets — detailing adds those.

Vendor / OTS parts

• Model interface envelope (bore, boss, cutout for body) in this pass.
• At most a short # VENDOR — <category>, <key dims> above the cut — no SKU paragraph until DFM.
• If a STEP file is injected, use cq.importers.importStep('file.step') per cad-generation.txt; do not redraw the catalog part.

Anti-patterns — refuse to emit

• rect(..., centered=False) — use .center(dx, dy).rect(w, h)
• cq.selectors.* — string selectors only
• Compound boolean tools (tool = a.union(b); body.cut(tool))
• Nested booleans in arguments
• .translate() on empty Workplane
• Reused rotated Workplane for multiple cuts
• Loft/sweep as boolean tools
• extrude(0) or revolve profile crossing axis
• Fillets/chamfers (detailing pass)
• Counterbores, tap drills, clearance pairs (DFM pass)
• Duplicating constants that exist in common.py

Validation before hand-off

1. python -c "import runpy; ns=runpy.run_path('parts/<name>.py'); bb=ns['result'].val().BoundingBox(); print(bb)" — non-zero spans.
2. Bounding box roughly matches envelope from common.py (± sensible feature tolerance).
3. Hand to orchestrator for cadquery-render and cadquery-interference-check — do not render from this skill.

Output

parts/<function_name>.py with build_<function_name>() and top-level result. No edits to assembly.py from this skill.