Mounted the aileron and set it in the neutral position. Temporarily riveted the skin and flap brace together with 4 rivets equally spaced to keep everything in place and allow the hinge to sit relatively flush. Drew a line 1/4 inch from the edge as a reference line on the hinge. Made sure I had 1/4 inch gap between aileron and flap with a piece of UHMW. Leveled the flap with the aileron. Everything was perfect. Began to drill.