I noticed that a few rivet mandrels had pulled through. I e-mailed Kerry at Sonex and he said this is common with flush rivets. I researched & experimented a bit. It's caused by updrilling to #30 before dimpling.
The procedure that works for me is 1) Drill (pr updrill) pilot hole with 7/64" (will still cleco fine), 2) Deburr & Dimple, 3) Ream with #30. The dimpling stretches the hole so that it's almost a #30 without reaming. Do this on both skins and ribs. Countersink the angle.
I sort of followed the instructions in the book. Clamp one side...
Line it up carefully...
Mark what parts go where...
Flip it over and press the skin down. Here you see a couple of match holes drilled and cleco'd.
Clamped & cleco'd
The leading edge bows without being cleco'd.
Catching the light off the ceiling!
