Selecting Edges
The following rules apply to edge selections for offset or thickened edges:
A circle is made up of two arcs. You must select each segment separately.
You cannot offset or thicken edges with a tangency that meets in a sharpened point.
When you select tangent edges to offset or thicken, select them using the Chain option. Otherwise, the section will fail regeneration because the individual offsets of the tangent entities will not be connected.
To use the entire edge to create an offset or thickened entity, you must create an untrimmed offset edge from a single edge.
When you delete an offset or thickened edge, the corresponding reference entities are retained. If you do not use these references in the section, they are deleted when you exit Sketcher.