To fit the ribs I have to first attach spacers at various rib positions so that every rib is mounted the same distance fore and aft from a common reference point. Adding the thick and thin spacers as needed makes the local spar mounting point for the ribs the same thickness as the thickest part of the spar. Two locations only need the thick spacer because they already have fore and aft spar web material at that location – just no center web.
After the spacers have been pilot drilled and mounted, I attached the forward ribs. I checked each rib, top and bottom, with two pieces of .025” sheet stock to simulate how the skins will lay on the spar and rib. I had to move five ribs up just a hair to get them all to fit like the one in the second picture below.
