Was a beautiful warm, still day in Roxby today, so I set up a trestle outside and spray painted the front and rear spars and spar doublers. I had four spray cans of two-pack epoxy primer and ended up using all four. Didn't help that one can didn't seem to have very much paint in it. I didn't get one side of one spar piece painted and it ran out. Will take that up with my paint supplier during the week (Update: they gave me another can for free.....no hassles.....impressed).
While laying out the spar pieces on my workbench I noticed that I made an error when countersinking the holes that require flush rivets. The bottom image below (caption: "Oops") shows what I did wrong, but basically, I now have one hole with a countersink on both sides. I've sent a message to Vans Support asking for their advice.
UPDATE: Received advice from Vans Support that it is acceptable to form a "double-flush" style rivet in this location.
