Can't Join intersection Breps in GH or in Rhino. Whats going on here?

Can’t Join.3dm (198.5 KB)

Can’t Join intersection Breps in GH or in Rhino. Whats going on here? They were created using a special VP component that extends surface edges. I then extruded the resulting surfaces to create these intersecting BREPS but can’t join them. any help?

These shapes are already closed. You cannot join closed breps. Did you mean to BooleanUnion them?

Doing some splitting using edge curves, I removed those parts of the shape that were overlapping and joined the results. It’s a fair amount of manual labour though, wouldn’t want to have to do this five-hundred times as part of a process pipeline…

Can’t Join.3dm (147.3 KB)

Yes a union is what’s I’m after - I’d like it to be one Brep. Union fails in both rhino and grasshopper. Any advice? Am I misunderstanding something about the nature of a Boolean Union?

And doing it manually in rhino not ideal - trying to make a gh definition that will involve performing a union about 100 sets of these…


One question is what is purpose of your design.
Is it going to be 3d-printed or CNC milled or something else?
In most real life application “precision” of CAD-model is far from precision of production processes (it is “better” then precision of tools we use afterward to produce/manufacture an item).
My approach is:(if BooleanUnion fails) to slightly displace solids (one by one) and try to BooleanUnion again. Our 1st process of manufacturing (3d printing) allows us to use this approach because preccision of 3d printing is 10 times less fine then precision of CAD model.
Let me explain it on simple numbers, for example if number 5.772 is output form CAD sw it will be “transformed” to 5.77 by 3D-printer sw, and and the same tie 5.774 will be “transformed” to the same value of 5.77.
And it is just first approximation that happens in first step of manufacturing process…

Conceptually no, but Rhino will get confused if you’re trying to union shapes which are coincident over large portions of their surfaces. Especially if those shapes are curved.

You can post this problem in the main Rhino category, maybe someone there has a better idea on how to make it more reliable.