The following diagram explains the difference between the ‘Envelope Normal’ and the ‘Wheighted Facet Average’ option; obviously things have been exaggerated here to show what’s going on. Within the envelope are two imaginary struts, which meet at the zenith. The cyan line shows the envelope normal **Ne**. The yellow line shows the weighted facet average normal **Nw** of the faces surounding the hub. Only the weighted facet average normal passes though the axial centre of the struts; and this yellow line marks the mitre for cutting so that both surfaces meet. The intention here, is that **Nw** passes through the axial center of all forces meeting at the hub.

Note: The envelope normals for concave superellipsoids are not always not well defined at the edges; so if using concave shapes please leave the hub normal option to ‘Auto’ as this will give the best results. I have deliberately avoided limiting the minimum exponent values to 2, which means concave shapes *are* allowed.