Okay. I thought that maybe it was the fillet I applied to the corners where the pipe goes from horizontal to vertical, and so I built another curve without fillets at that point and when I ran pipe, – it didn’t twist. I wonder if this would give us a clue as to what caused the above file (Why is this pipe twisting.3dm) to twist?
Hi Cosmas- for some reason, orienting the cross section as it twists through World Z has always been problematic- I don’t know the details… the one that works starts and stops (miter) and I guess this is why it is OK. I guess the workaround is to do the porblematic pipe in bits - in this case not too painful, you can explode the curve, keep them all selected and Pipe, Cap=None. Join the result and Cap (if needed).