Trimmed E-604 rib flange more. Drilled holes in each corner. Clamped E-613 skin to 603 & 604 tip ribs and drilled 604 to 603 using #30 bit. Deburred holes.
Drilled hinge brackets to spar using #30 bit. Deburred holes. Cleaned up edges of skin using small Scotchbrite handheld tool and sandpaper.