Unwanted lines appear when I intersect a group that has curves in it



I have attached what I am talking about - the hole with a lip that you can see going through the main object is a group that I have intersected with model. Around the lip it has decided to add in many lines that correspond to each point in the circle. It is flat so I can delete them without breaking the surface.

Can you say why it creates these unnecessary lines?


Not without the file. What size are the circle segments?
Being able to delete the added edges doesn’t necessarily mean for 100% that all geometry is coplanar. There is a tolerance involved.


Here it is

rim1.skp (2.8 MB)


Hello, I’ve had many problems like this with the intersect tool that I talked about in another topic. Many coplanar unwanted lines are created. I was waiting for it to happen again to make a post about it. I can’t check out your file now as I don’t have 2018 at home, I’ll check tomorrow at work. But i’m glad (in a way) someone else noticed that !


I isolated one face with circular intersection and although I could also delete the unwanted edges like you said, the remaining “face” with circular hole appeared to be not coplanar at all. All differences in coplanarity seemed to be within tolerance. This incoplanarity could be due to placing the “ring” group on a face without 100% accuracy. Intersecting would probably drag intersection endpoints out of plane.
Maybe you will get better results if the group with circular ring would be a ‘Glue to’ component instead. To ensure gluing correctly to the face.


I’ve observed that when SketchUp decides two edges were meant to intersect or coincide it will “pull” one over to match the other so they can share a vertex. Depending on which edge dominated, the vertex may be pulled out of plane, causing SketchUp to triangulate even when it could have decided the point was in plane. I don’t know a reliable workaround.


I think here we need the file before the intersection is made. To see how the group is positioned on the face.


I positioned the group through one plane of the target surface using snaps.

Put one end of the ring onto one side, then rotated to the plane with snap.


I’m wondering if you could use two different segment components for this rim. One with the eyelet in the center of the flat area and the other a “plain” segment. This way you will avoid having the eyelet in the joint of two segments.



This topic was automatically closed 91 days after the last reply. New replies are no longer allowed.