Well, on your jig, the two magnets have allen screws set into them. WIth these, you can loosen the screws, and then turn the dial to get the desired amount of offset. As far as getting an exact 3 degrees, I'm not sure how to measure that exactly. I fletch helical for all my arrows, so I get as much difference in magnet height as I can while still maintaining contact throughout the entire length of the fletch. I fletch a ton of arrows for the shop I go to, and for the offsets, the jigs have always been set, so I never messed with them for the offsets. I would say, if nothing else, you can eyeball it!