Blending between open and closed edge chains


Can anyone explain why is this happening in my model? It looks like bottom edge of the surface at the top is built of 2 edges. Why did this happen? how to avoid these tiny defects in the future?

Thanks in advance

rhino forum.3dm (188.7 KB)

Hi Radovan - that can easily happen - it depends on what it nay have been joined with previously or trimmed by, - use MergeAllEdges, in this case, to merge the fragment.into the larger edge. Note you can chain edges inside the BlendSrf command as well.