For JR.....how i went about the ticklish process of getting the root ribs in the lower wing halves positioned...A critical step.....I pinned the gage to the rib itself and then dropped ithe assembly into position prepared with t pins set on the plan line. When i got it where it need to be, i welded it to the lower spar. Be sure to double check that you don't shift things when you add the upper spar. Hope this helps.