About Boundary Blend Reference Entities
When you select curves for a boundary blend surface, you can select curves in the first and second directions. In addition, you can select additional curves that the blended surface will try to approximate.
The rules for selecting reference entities are as follows:
• Curves, part edges, datum points, and ends of curves or edges can be used as reference entities. Datum points or vertices can only appear first or last in the collector.
• In each direction, reference entities must be selected in consecutive order.
• For blended surfaces defined in two directions, the outer boundaries must form a closed loop. This means that the outer boundaries must intersect. If the boundaries do not terminate at the intersection points, the system automatically trims them and uses the relevant portion.
• If you want to use continuous edges or more than one datum curve as one boundary, select curve chains by holding down SHIFT.
• Curves selected for blending need not contain the same number of entities.
• When you specify curves or edges defining the shape of the blended surface, the system remembers the order in which reference entities were selected and assigns an appropriate number to each chain. You can rectify the order by clicking the curve set in the reference table and dragging it wherever required.