cad

## What I do - Create 2D drawings and 3D models of mechanical parts - Generate technical documentation and manufacturing files - Perform geometric constraint solving and parametric modeling - Support assembly design and component routing - Export designs for manufacturing or simulation ## When to use me - When creating mechanical designs for manufacturing - When generating detailed engineering drawings - When building 3D models for visualization or simulation - When designing assemblies with multiple components - When preparing files for CNC machining or 3D printing ## Key Concepts ### CAD File Formats | Format | Type | Applications | |--------|------|--------------| | STEP | 3D neutral | Exchange, CAD interoperability | | IGES | 3D neutral | Legacy CAD exchange | | STL | 3D mesh | 3D printing, rapid prototyping | | DXF | 2D | Drawing exchange | | DWG | 2D | AutoCAD native format | | OBJ | 3D mesh | Visualization, 3D graphics | | Parasolid | 3D | Siemens NX, SolidWorks | ### Parametric Modeling ```python # Example: Creating a parameterized part class ParametricPart: def __init__(self, **dimensions): self.dimensions = dimensions def create_sketch(self, points): """Create 2D profile from points""" return { "type": "sketch", "entities": points, "constraints": [] } def extrude(self, sketch, depth): """Extrude sketch to create 3D feature""" return { "type": "extrude", "profile": sketch, "depth": depth, "direction": "positive" } def create_hole(self, location, diameter, depth): """Create a hole feature""" return { "type": "hole", "center": location, "diameter": diameter, "depth": depth } ``` ### Geometric Constraints - **Coincident**: Two points occupy same location - **Collinear**: Points lie on same line - **Parallel**: Lines have same direction - **Perpendicular**: Lines intersect at 90° - **Concentric**: Centers coincide - **Equal**: Dimensions or radii match - **Tangent**: Curves touch without crossing ### Assembly Design ```python # Assembly constraint types ASSEMBLY_CONSTRAINTS = { "mate": { "description": "Two faces in contact, opposite directions", "degrees_removed": 3 }, "flush": { "description": "Two faces coplanar", "degrees_removed": 2 }, "angle": { "description": "Constrained angular relationship", "degrees_removed": 2 }, "insert": { "description": "Axial insertion (e.g., pin in hole)", "degrees_removed": 2 } } ``` ### Common CAD Software | Software | Vendor | Strengths | |----------|--------|-----------| | SolidWorks | Dassault Systèmes | Mechanical, assemblies | | CATIA | Dassault Systèmes | Complex surfaces, aerospace | | NX | Siemens | Advanced manufacturing | | Inventor | Autodesk | Mechanical, simulation | | Fusion 360 | Autodesk | Cloud, accessible | | Onshape | PTC | Web-based, collaboration | | FreeCAD | Open source | Free, parametric |