Step 1: Counterskin skin holes of Longerons. Set up the machine countersink to a +.006 to .007" beyond that for flush 3/32 rivet to accommodate dimpled skin. But half way through the countersink of first Longeron I managed to get the C-skin pilot stuck slightly and broke it off when extracting it. No damage but slowed me down for the night. Ordered more. I did not realize how little material there was that holds on to the pilot shaft of the Single Flute Countersink Cutter until I broke it off and had a look. The machine steel is already hard (read fragile) and I got too agressive with it when it stuck slightly. I suspect a little lube would help next time.
