You are right, in the picture I posted there are no T-junctions, however once you 'drill' a hole you get them. You can clean them up by joining the vertices, sometimes this function stops working, so open and close the file again.
The CSG is really nice, but I will do the shape now in a two step approach.
First I thought the wall is too thin, just 2,5 LDU but the strange tri-angles do not depend on the size of the inner sphere. When I do the complete sphere with CSG, I also get "shadows" of the intersection of the axle-hole with the inner sphere projected onto the outer sphere.
The CSG is really nice, but I will do the shape now in a two step approach.
First I thought the wall is too thin, just 2,5 LDU but the strange tri-angles do not depend on the size of the inner sphere. When I do the complete sphere with CSG, I also get "shadows" of the intersection of the axle-hole with the inner sphere projected onto the outer sphere.