Today was another long but highly productive day. First I match-drilled both skins using a #40 reamer and a drill bushing to keep the bit perpendicular to the curved surface of the skins. Then I carefully disassembled the parts. (Both of these tasks took a lot of time with over 500 clecos to relocate during match-drilling and then the same number to remove during disassembly.) Afterwards I countersunk the rear spar deep enough for a 3/32" rivet to sit slightly recessed in the hole and a #40 dimple gauge to sit flush in the hole, but not so deep as to create a knife edge at the bottom of the hole. Once again, this took a lot of time since the holes on both flanges of the entire length of the spar had to be countersunk (i.e., approximate 22 linear feet or almost 200 rivet holes). Finally, I deburred the freshly drilled holes in the inspar ribs and nose ribs and then dimpled the flange holes with the pneumatic squeezer, being careful not to dimple the specific holes called out in the plans for the empennage fairing attachment screws and the horizontal stabilizer fairing tip rivets.
