You know it is funny. When I got one of these things I figured all my chores of getting edges flat and 90 degrees were over. Then I discovered a thing called the Carolus effect or so some smart person told me it was called. The Carolus effect is that a spinning wheel spins at different velocities depending on how close you get to the center. In other words, the velocity of the sanding decreases the closer you get to the center or increases the further you get from center. It also has something to do with angular momentum or such things that put me to sleep in school. Anyway, I've learned to compensate. Nothing is ever easy. Another thing I have learned is that these things will take off wood real, real fast. Almost too fast. Sometimes I wonder if a smaller set-up would be better for lutherie. Something like a small scroll saw versus a big honking band saw.