Hi Pilou,

> After a sweep some open profil were rotated for any
> reason so some twists are created

Do you have an example of this?

Sweep does not actually use only the natural direction of the profile curves - it analyzes the curves and automatically flips them as necessary to reduce twist.

I've attached a sample file here to demonstrate - note that the profile curves in this case have their natural starting point on opposite sides from each other like this:



However, when you sweep these, there is no twist, and there is no need to flip any profiles manually:



This is one of those things that makes MoI friendly to use - it automatically changes the orientation of profiles as needed to eliminate twisted surfaces so that you do not have to worry about which side is the natural start and end and manually orient them like you have to do in some programs.

- Michael