Find out how to control rotation parametrically in Revit in this tutorial. Watch more at http://www.lynda.com/Revit-Architecture-tutorials/Revit-Family-Curves-Formulas/148423-2.html?utm_campaign=i97k1zlUq5I&utm_medium=viral&utm_source=youtube.
This tutorial is a single movie from the Revit: Family Curves and Formulas course by lynda.com author Paul F. Aubin. The complete course is 3 hours and 51 minutes and shows how to tame unruly parametric curves with the Revit Family Editor, and start controlling circles, arcs, arches, splines, and even complex curves like cyma moldings.
Introduction
1. Understanding Parametric Curves
2. Controlling Rotation
3. Arches
4. Using Formulas to Control Curvature
5. Compound Curves
6. Scaling and Proportion
7. Combining Strategies
Conclusion
Source