O.k., here's a few more details for you. I don't have an Edge Pro, but I think I know enough about how it works to help.
To get the same angle, do 2 things. Do the magic marker thing, and eyeball the angle at first. Take a swipe with the stone, and check to see if you got the angle right, as per my magic marker instructions. Then adjust the angle of your rig as needed.
Good luck!
Hmm.. AR and an Edge pro: you have good gear man!