Tonight, I began preparing the left wing aft top skins prior to dimpling them. The skins overlap, and while there is not a structural need to thin the material where they overlap, Vans suggests this in order to improve the aesthetics of the joints. I used my drill and some sanding attachments I picked up at Oshkosh this year. They worked well, and I was able to thin the skins with precision. I used my digital calipers to verify thickness. I then cleaned and primed the faying surfaces since they had been sanded and scuffed.
Drill and sanding attachment
Primed faying surfaces.
I also primed the wingwalk back up skins and inboard skin faying surfaces.