The edge of the selected face is not valid for a fillet face.
Fillet faces are required to have a spring edge. If you think of fillet geometry as being created by an imaginary rolling ball that maintains contact with the surfaces to be filleted, the two edges of contact are called spring edges. Two common causes of missing spring edges are covered by other error messages:
- The fillet face has the same radius as an adjacent face.
- The radius of the curve across the fillet is greater than the radius of the edge along which the fillet is modeled.
This error message appears when other geometries create improper edges and Featureworks cannot determine the cause.