Decide to countersink the holes on the rear spar before priming this time. Seemed like an easy morning task, but took longer than it should have.

Had the countersink all setup already from a previous session. Did one hole and checked depth with a rivet, looked good - about 0.007” recess. Proceeded to do all 29 holes but could tell by the end that they were not deep enough. Couldn't figure out why the cage wasn't fully seating. Finally saw I was hitting the stop on the drill press. Fixed that and re-hit every hole to the correct depth.