I’ve been asked to construct a corner fillet in the attached. What makes this one a little different is that the solution has to retain as large a portion of the 38mm radius sphere as possible in the corner fillet surface. Edges marked 1 are arbitrary and can be adjusted as required. The edge of the small fillet surface (2) has to stay where it is. The two 38mm fillets aren’t set, but I’ve aligned them tangential to the sphere. The missing surface has to remain convex throughout and must finish tangent to any retained portion of the sphere and other boundary surfaces.

I’ve tried a few ways of generating a solution, but so far it’s defeated me. Anyone here got an idea?

Corner Fillet.3dm (315.6 KB)