Hi Paul,

Sorry, bad day yesterday.

I have taken your surface (the one you built in "other"),.... created the surface in MoI based on the curves you posted ("please try" curves), and created the surface in Rhino 4(with those curves).
This is the output for surface analyze in Rhino 4. You will note the surface you created in "other" is in error (there is a kink or crease), as the surfaces match to position only (G0), from MoI and Rhino the surface looks much better for curvature and tangency and looks G2







- manz