Pat, you are correct but it lets me move fast and keep the same angle. trying to go fast and resetting the stroke everytime takes longer. When im doing a dozen new broadheads at a time and they all need thier angles changed the scrubbing goes much faster. Thats why i showed that you can do both normal strokes or scrubbing strokes whatever you want to the choice is yours. I have never noticed any dulling to the file. Broadheads are really soft so i dont think they would dull a file.