Inconsistent results with Solid Union - not always working

Hi , I notice some weird inconsistency when trying to Union a bunch of Closed Breps. For certain values (nb of units in X and Y direction) it works and I get a single Closed brep. While for others starting values it just doesn’t and the Brep union is incomplete. See attached screenshot. I attach a cleanup GH file with these 3 starting conditions. The initial curve geometry is all similar, just a change in orientation in a plane.

While all geometry before Solid Union is a Closed Brep, could it be that the issues is with starting curve none the less? I tested to bake in Rhino and the Union operation failed as well, like in GH. Same for Mesh Union. Any feedback would be much apricated

Solid (119.0 KB)


I got this to work by replacing the Ruled Surface by a straight Loft.

The Loft is however considerably slower than the ruled surface, so I used some C# wizardy to get it to work also in that situation.

Solid (114.2 KB)

Thanks for the fast reply. So should have posted sooner this morning, you could have saved me some hours debugging :wink:

The question is why does this behavior occurred in the first place? Is there a common way to prevent this? I see that you check whether splitting occurred with SplitKinkyFaces , why is this?

Rhino automatically “cleans” Breps when they are added in a viewport, but Grasshopper does not. In many cases when working with boolean operations, this is required (and unfortynately there is no native component that does that)

Ok, First time I encountered it. Still find it weird that it’s not consistent and sometimes it does work. It’s not a bug but a feature right :wink:

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