Hi there

What a great question
The closest I have come to, in trying to achieve this, is.........

- Twistedrod_01.jpg (13.77 KiB) Viewed 1565 times
I did this in the "Conceptual Design Environment". I created a series of profiles, all on different levels- one above the next. And then just chose "Create Form".....

- Twistedrod_02.jpg (7.02 KiB) Viewed 1565 times
This bascially just uses the "Loft" function of Revit. Once you have produced a full "revolution", you could then just copy this as many times as neccessary to create the complete twisted part of the rod.
A tutorial on forming "Lofts" can be found here.....
http://www.revitzone.com/conceptual-des ... -loft-formI'm sure there are other methods of doing this and would love to hear from othere.
Cheers,
Ian