Hi Stefan, sorry I misunderstood I was thinking that it was booleans failing with the 2 vs 3 thing.

Doing the fillet on the 2 cylinder case is indeed a much more difficult fillet because it's a "disappearing fillet" type arrangement where the fillet shrinks down and down to a single point. The fillet engine that MoI uses tends to have problems with that type of fillet. In the "3 cylinder" case there aren't any fillets that have to behave like that.

For the "2 cylinder" one, it's possible to finish it by some manual work if just one of the fillets can be created. You can mirror the one fillet over and then use trimming to cut the cylinder pieces with the fillet edges. That's how I finished the attached version here.



- Michael