Library Conventions | KiCad EDA

Version 3.0.43

Library maintainer rules & guidelines

M2.2 Model alignment and scaling

The 3D models must be aligned and scaled appropriately to match the associated footprint.

Alignment

The 3D model must be aligned such that it does not require an additional alignment offset in the footprint options. When associating a 3D model with a footprint, the offset parameter must read (0, 0, 0)

Scaling

  1. STEP files include absolute dimensional information, and must never have a secondary scaling factor applied. The model scaling parameter in KiCad must read (1, 1, 1)

  2. WRL files do not specify absolute dimensions. The WRL fileformat has no way do specify what its units mean. KiCad considers one WRL unit to be 0.1 inches for historical reasons, so models must be scaled accordingly.

    1. Assuming the model is designed in mm then the required scaling factor for WRL export is 1/2.54 (~0.393700787).

    2. The Freecad extension kicad-stepup exports WRL files already correctly scaled.

Rotation

The model must be rotated such that no additional rotation is required within KiCad to align the 3D model with the footprint.


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