Reviewed plans and re-assembled the brackets to mark locations of countersunk rivets. I also did double countersinks for the aft rivets on the inboard bracket to allow for double flush rivets. On the flat plates I could use the micro-stop countersink cage to get the countersinks flush. For the angle brackets I set up the countersink bit in the drill press and used a gradual approach to cut and check the countersink depth.