Hi Forum. The goal is to produce a taper in a series of cylindrical surfaces like that shown in the center of the attached. Easy enough using different ways the simplest I've found being isocurve trim at taper location->scale/resize smaller section->delete surface intended for taper->loft between larger and smaller closed edges of adjacent surfaces. Other ways welcome. I'm curious why I can't get control points for the three distinct surfaces after I add isocurve trims from above sequence. Instead the control points still appear for the bounding box of all three surfaces. It would seem that a closed curve, not a closed edge is necessary for control points. Where can I read more and is there a way to do isocurves that provides control points such that I can better manipulate the tapered section ?

Thank you, Sven

After that on any surface you can use any point(s) for any transformation!
But i am not sure to understand the question! :)

Hi Sven, when you trim a surface including with an isocurve, it modifies the trim boundaries but the underlying surface remains the same.

There is some description of this here:
https://moi3d.com/faq#Q:_Why_does_show_points_work_for_some_objects_but_not_others.3F

If you want the surface control points to end right on your isocurve trim, you can use the ShrinkTrimmedSrf command to shrink down the underlying surface so that any surface that is outside of the active trim boundary will be discarded.

- Michael

Thanks Michael, just what I need.

Sven