Split failed object may not intersect

I am having problem with the split. All the other areas I projected line to surface split no problem. But there are two lines one on each side of the ring that is giving me failed message. I can’t see why the line is an issue since the same line projected on the other side of the ring split no problem. Can someone let me know why this is happening? I am working on the Mac latest version.bombe.3dm (5.6 MB)

Hello - can you attach the file directly in your post? Use this button:


Moved to Rhino for Mac

@annachandesign Choose a Category so your post will get indexed and get the ‘best’ answers

if you pull the curves to the surface, the split works ok. in some case maybe you need to ExtendCrvOnSrf after Pull to ensure reaching the edges of the surface and then Split.

Great thanks!