My MPG's don't have indents and are setup up ( counts per unit & velocity settings ) to somewhat provide for "turning" feel as if using a manual handwheel.
IE; turn slow and get small movements and turn fast and get faster movement of the axis. I think one turn of the mpg is around 0.008", thus great for positioning. I have used them to do some machining, but it takes a "heightened awareness" of what you are doing, thus it's just not as natural as say a manual handle since control can be lost and also there is no "feel" of the actual machining.
FWIW,
RICH