Designers: What do you charge hourly for web design work after a project has passed the initial scope?

Depends on the size of the project (will I have to hire outside help), how much I'll learn by doing it (I'll charge less if I learn something) and how interesting the project is (I'll do it free if I really want to do it anyway).

But my starting point is around $100/hour. (Having been cutting code for 35 years lets me do it in less time than some other people might.)

charge whatever you want.