Leveled the fuselage to within .1 degrees all around, centered and measured. Placed the appropriate shims in front and back and began drilling. Lots of measurements to make sure the bolts are centered, lots. Started drilling with 40 then 30 then 19 and final drilled to 12.
Made a drill shim of sorts which is the height of the bolt holes above the aft deck. This way I can use a long drill bit and make sure it’s level by holding it back 6 inches from the hole so it’s level in the horizontal.
Drilled the front horizontal spar with an pancake drill. Edge clearance for the outboard bolt holes is not perfect but a thread on vansairforce.net indicated that Vans said the structural integrity comes from the longerons.