Hi Kevin, yeah that sort of thing means the scaling rail is not being hit and so it's not extending quite far enough. When the sweep is not able to hit the scaling rail at a particular point, it reverts to the original unscaled sweep at that spot and that kind of sudden jump in shaping makes that kind of result that you saw.

The way the scaling rail works is the thing that needs to hit it is the plane of the "sweep frame" at each spot along the rails which is not necessarily the same thing as where profile itself actually is at, especially if the profiles are at some angle to the rails.

In the future maybe it would be good for me to internally extend the scaling rail if the sweep runs into this type of thing where it isn't able to find an intersection...

- Michael