I use my Dremel for a lot of different things. Never for cleaning up fret work though. I would also think at high speeds the bit would want to burn the wood. I have used thin pieces of wood with sandpaper glued to them for cleaning up interior cuts that weren't just right or even just a piece of sandpaper cut into small strips. Not sure if this is what your looking for in an answer. A lot would depend on the thickness of the cutting, type of wood, etc.... Maybe a picture of what you are trying to accomplish would help more.