From FreeCAD Documentation
- Optionally, select the Arch Axis objects you wish to include in this system.
- Press the Arch AxisSystem button.
- Right-click the newly created axes system object in the tree view to add/edit the Arch Axis objects included in this system.
- Select any existing Arch Axis and press Arch Add or Arch Remove buttons to add or remove it to/from this system.
- Set the DataAxis property of any Arch object to point to this system, to have its shape duplicated to the intersection points of this system.