My brother Bernie helped me with the wing aft spar preparation. We identified the spars and doubler plates and marked all the component orientations. We edge finished the components then attached the components to the spars and match drilled everything followed by deburring. Also the spar upper flange next to the inboard doubler was drilled to final dimension, deburred and dimpled as this will not be possible once the doubler is riveted in. See image 1.