I can’t boolean union the object. v.3dm (1.0 MB)
It gets like this:
You’ve got a few naked edges on the main ring, and the normals are flipped, causing the ring to be “inside-out”. Repair the naked edges (some long, skinny surfaces in there) to create a closed polysurface - then your boolean will work just fine.
v_JN.3dm (899.8 KB)
Thank you! How can I detect flipped normal and how to flip them well?
When a polysurface is open, Rhino has no way of telling what side you perceive as “the outside”. Use the command Dir to see little arrows indicating what Rhino sees as the outside and then use the Flip command to… well, flip them. As soon as you’ve got a closed polysurface it is no longer an issue, since Rhino can now easily determine which side is in and which is out