# Parametric Involute Spur Gear .DXF & 3D .STL Generator

Generate true parametric involute spur gear pairs with 0.005mm AutoCAD R12 .DXF and watertight 3D-printable binary .STL including hub boss, keyway, and contact ratio check.

## Engineering Geometry & Export Specification
- Computes exact parametric involute flanks x = rb*(cos t + t*sin t), y = rb*(sin t - t*cos t) with ISO 53 root clearance and transverse contact ratio verification.
- CAD Outputs: 0.005mm AutoCAD R12 `.DXF`, `.SVG`, Watertight 3D Binary `.STL` (4–40mm face + hub boss + bore), and `1:1` Printable `.PDF`.
- Pricing: Free Spec Proof PDF ($0) · Single CAD Pack ($11.90) · Mechanical Engineer Pro ($19.00/mo).
- Live Interactive Workbench: https://gearcadpro.com/templates/involute-spur-gear-dxf-stl-generator.html