Boolean union failed

I have two breps created with grasshopper. One of them is an extruded brep, the other one is a revolved surface. I trying to unify them the be able create an object to be 3d printed. Unfortunatylelly the boolean union is failed. Maybe another approach is needed during the process of generating the items to be able to unify them successfully. Can anyone tell me how?boolean union problem.3dm (426.3 KB)

Hello - that will be tricky - the small cylinder just touches the walls of the notch, (Use Intersect on the two objects to see the problem, in a Wireframe view) which makes for a non-manifold edge there even if it did work - make the cylinder either slightly larger to get e full intersection or slightly smaller to miss the walls of the notch completely.

I see thee is a problem with the bottom face of the smaller object as well - you’ll want to fix that.


I dont really understand what you mean. Are you saying that the revolved object is corrupt in a way? Or they just dont fit to each other?

Hello - I think there are two problems-

  1. The bottom cap on the little cylinder is ‘funky’. ExtractSrf and turn on points for this surface to see… it is easy enough to fix in Rhino, but if you are making this in GH, you should check that part of the process.

  2. The walls of the cylinder just touch the walls of the notch - the intersection there is a line, not a good situation. If you make the cylinder slightly wider, it will intersect the notch fully, and not just barely touch, or if you make it slightly smaller, it will not hit the walls and cause that line intersection. My guess is either would work but probably the make-it-larger version is more like what you probably want.

Bottom surface replaced and the thing made slightly larger- boolean union problem_PG.3dm (380.3 KB)


I am trying to go back to the root of the problem so I made a much simpler situtation. I made a tringle and revolved it. I made sure that the bottom is wider than the notch of the larger part. Still no success. I don really understand.
boolean union problem simple.3dm (244.9 KB)