Completed deburring the bottom of the ribs, inside and outside. Used the squeezer and dimpled the ribs top and bottom. After dimpling the rear spar I cleaned up the dimples with a couple of turns of the deburring tool per the plans.
Set up the countersink for flush plus 7 thousandths per the plans. Checked first countersink with a rivet as well as a piece of .025 scrap dimpled to simulate skin. Rivet was slightly deep and "skin dimples" fit well, so I continued to countersink the outboard rivet holes on top and bottom of spar. Occasionally re-checked countersinks with rivet and "skin".