This was a brief session to un-cleco the inboard upper skin and the wing-walk doublers, and then begin dimpling them.

Although the instructions recommend countersinking rather than dimpling the skins in the wing-walk area, I've decided to deviate and do dimpling instead. This choice has been made by a number of other builders on VAF for a variety of reasons, but should result in slightly stronger though slightly heavier build (due to no removal of material and needing slightly longer rivets).

I then used my combo belt/disc sander to remove some of the material thickness in the leading edge corner where the two skin pieces overlap. I was initially attempting to use just sandpaper and scotch-brite wheel in my power drill, but those were both taking too long so I switched to the circular part of my combo belt/disc sander and that took care of it in a few seconds.

I also used a scotch-brite pad to scuff up the wing-walk doublers, and the contact areas of the underside of the inboard upper skin, to prepare them for eventual priming.