version: "1.0.0" name: cad-original-design description: Use when a CAD, SolidWorks, FreeCAD, STEP, DXF, DWG, STL, part, assembly, mechanism, fixture, bracket, enclosure, tool, or mechanical drawing must be designed from requirements without a reference drawing, screenshot, PDF, scan, or existing CAD file to copy.

CAD Original Design

Core Rule

When there is no reference drawing, do not use reference-matching criteria. Design from function, constraints, interfaces, loads, manufacturability, and acceptance tests.

Design Brief

Before modeling, create a concise design brief:

Use cad-requirements-lock for missing blocking facts. If the user wants assumptions, record them as assumptions.

Concept Pass

Generate at least one coherent concept before CAD:

• name the design type,
• explain the load path,
• explain how it mounts or mates,
• identify critical dimensions and degrees of freedom,
• identify likely failure modes,
• define function zones and standard mechanical features,
• run cad-engineering-sanity for load path, interfaces, wall thickness, hole edge distance, clearances, fits, material, and unverified strength claims,
• define the minimum professional drawing elements,
• choose a manufacturable feature set.

For nontrivial parts, compare two concepts briefly and pick one. Do not over-design beyond the task.

Modeling Rules

• Build parametric geometry from named dimensions when possible.
• Keep interfaces and datums explicit.
• Prefer standard fasteners, hole sizes, clearances, radii, and stock thicknesses.
• Add fillets/chamfers for function or manufacturing, not decoration.
• Preserve design intent in the source script/model so dimensions can change.
• For drawings, dimension functional features and interfaces first.
• Use cad-design-richness to prevent under-designed blocky geometry.
• Use cad-visual-layout to prevent sparse or informal plotted drawings.

Original Design Checks

Before final reporting, check:

• function matches the design brief,
• interfaces are present and dimensioned,
• load path is plausible,
• engineering sanity result is pass, partial, or fail with Verified/Inferred/Unverified claims labeled,
• wall thickness, fillets, hole edge distances, and clearances are reasonable,
• manufacturing method is plausible,
• complexity target is met,
• required professional drawing elements are present,
• visual layout target is met when a drawing/PDF is delivered,
• deliverables are generated from the current source,
• unverified engineering claims are labeled as unverified.

Use cad-design-richness before accepting the mechanical concept. Use cad-visual-layout before accepting a formal drawing sheet. Use cad-final-verification for final file checks. Use cad-toolchain-preflight before relying on CAD automation or external tools. Use cad-engineering-sanity before claiming fit, strength, load capacity, manufacturability, or mechanical plausibility.

When Not To Use

• If a reference drawing/image/PDF/DWG must be copied, use cad-reference-match.
• If the task is only checking final files, use cad-final-verification.
• If the toolchain itself is unknown, use cad-toolchain-preflight.

Reporting

Report:

• design brief,
• chosen concept and reason,
• key assumptions,
• generated files,
• verified design checks,
• engineering sanity result,
• visual layout result,
• design richness result,
• unverified engineering risks.