In this session, I clecoed the spar doubler plate to the spar and final drilled all of the matching holes. A couple of the larger 1/4" holes were called out to be final drilled using a drill press, so I did that too. Next, a dozen holes on the spar doubler and a bunch more on the spar flange had to be machine countersunk to allow flush rivets to be later installed.

Then I unclecoed all of the parts and begun a final deburring of all of the new holes, and then a quick scuff of all of the surfaces with a scotchbrite pad and a wipedown with acetone to prepare for priming.

What's next? Time to prime these parts and then begin riveting these spar parts together.