On a similar note, when you are defining a revolved feature in the sketcher, draw your axis of revolution first and then you can dimension a diameter by clicking a sketched entity, axis of revolution and the same sketched entity again. This way when you use "Show and Erase" in a drawing and pick your revolved feature, you get diameter dimensions automatically, and you can then (assuming your sketcher dimensioning scheme is adequate) drive your revolve features from the drawing.