From FreeCAD Documentation
- Apply the displacement boundary condition to a face first.
- There are several ways to invoke the command:
- Press the Local coordinate system button.
- Select the Model → Geometrical analysis features → Local coordinate system option from the menu.
- Select rectangular or cylindrical transform. The former can be applied to any face, the latter is available only for the cylindrical faces.
- Select a face to which the displacement boundary condition was previously applied. Press the Add button.
- For rectangular transform, specify a rotation about each of the three axes. Arrows displayed on the face represent the new directions (X - red, Y - green and Z - blue).