Hi JTB, yup it looks like a bug, but it is not too surprising to me that very slight angular changes makes it difficult for the booleans to figure stuff out.

That causes very tiny spaces between the edges of the different pieces, because your movement downwards was in a different direction, basically those 2 boxes are not aligned with one another.

The booleans generally work better when objects like that are aligned precisely, like in that case it would mean moving the copy along the same angle downwards (instead of straight down in z) so that it was aligned with the other box instead of shifted by a tiny distance away from the other box.


Can you please post a .3dm example file as well, I will gather it up with some other bugs that I will send to the people who make my geometry library to see if they can improve this, it may take a while before that happens though.


But do you actually want to create a model with mis-aligned pieces and tiny slivered surfaces in the result? That would be basically what would happen there.

Generally it is good to avoid situations that create teeny-tiny slivered bits, they tend to make things difficult for intersection calculations.

- Michael