How to build a happy surface from two curves?

I’m trying to build a happy surface from two intersecting curves. I can create a surface easily enough, but when I go to offset an edge curve on the surface, the command fails. I think this is due to the u and v directions becoming parallel at the ends.
How do I avoid this problem? I’m guessing the solution involves building a larger surface and trimming it with the origonal curves. If I’m right, what’s the smart way to go about this?
Thanks- Patrick
pointedbananna.3dm (812.9 KB)

That surface seem pretty happy to me, I think the problem with offset curve is that it sort of runs out of surface to offset the curve on. Does ExtractIsoCurve maybe produce something you’re after?

Hi Patrick - I’d say OffsetCrvOnSrf is failing due to the pointy ends (singularities) If you clip the ends of the surface off (Split >Isocurve) even quite close to the ends, OffsetCrvOnSrf does work. I don’t know if that is just a ‘thing’ with singular surfaces, I’ll have to test…


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That sounds much easier than my work around.
I extended my surface on both sides, used the surface normal at the points to build two line in parallel to the surface at the ends, re-lofted using extracted iso-curves, and then trimmed it back with the initial curves.