Hi Brian, Hi Pilou - definitely a bug in the booleans there, I will put it on my list.

Sometimes saving and reloading can make a difference because when a sphere is first created it has a special mark on it that labels it as a surface of revolution.

Then in the booleans the intersection calculation uses some special case stuff for surfaces of revolution, which in this case seems to have the bug in it.

When it is reloaded, that special "surface of revolution" mark is not there anymore, and it goes through the general purpose intersection processor which actually works better in this case.

- Michael