For the Robin Hood (or Geena Davis) in your household. Simple fixture uses four bearings with shoulder bolts mounted in an offset fashion on an aluminum frame built from 1/4 X 2 aluminum stock. Position indicator at midpoint and turn. "Tweak" arrow until indicator shows no run out. I know nothing about archery, but several of my students built these......and seemed very satisfied with them. Left picture is overall shot with indicator. Right picture is close up of offset bearing setup.