In this session, I used a new step drill to enlarge the various holes in the left wing ribs. I found writing the desired hole diameters next to their holes on each of the ribs made the step drilling process much quicker, since each rib has different numbers and sizes of holes. After drilling the holes, I deburred them all, then scuffed the surfaces of the ribs, wiped them down with mineral spirits, and sprayed a layer of primer. After both sides had dried for a few minutes, I moved them all inside to finish curing over night.
What's next? I'll need to re-identify which ribs go in which positions, install all of the snap bushings, and start assembling the ribs with clecos.