Techniques for controlling arc length via parameters have been discussed here in the past - if you can't find the solution post back and I'll see if I still have an old file example.
Please mark this response as "Accept as Solution" if it answers your question. ----------------------------------------------------------------------------------------- Autodesk Inventor 2013 Certified Professional Autodesk AutoCAD 2013 Certified Professional Certified SolidWorks Professional Inventor Professional 2013 SP 1.1 Edu 64-bit GeForce GTX 560M i7-2670QM @ 2.2GHz 8GB RAM http://home.pct.edu/~jmather/content/DSG322/inventor_surface_tutorials.htm http://www.autodesk.com/edcommunity Still waiting for -Draft option on any Rib feature.
