Hi Burr, oops I forgot about the twisting.

There is a Twist: option in Sweep which allows you to choose between the standard minimal gradual twist, or a twist that only rotates around the world z axis.

Neither one will do a "Twist only around some various different normals of surfaces that the curve happens to come close to" though.

Aside from the twist parameter though you can add in additional profiles to control it.

Like if you repeat the circle positioning at the end so that then you have 2 circles, that would enforce the profile position at that area, possibly doing that at that spot and maybe 1 or 2 others would do the trick.


That would be a benefit of having the rail curve itself offset from the surface though rather than the profiles - it would be basically immune to the twisting, since the twist would be around a circle's center point instead of its side-quadrant point. But probably harder to set up the central rail curve though.

- Michael