Before match drilling the skins, the plans call to drill holes for the center ribs. This took some fine tuning and fitting but with lots of clamps. Also drilled the front and rear rib flanges to the front and rear spars. Not a complex task, but takes time to make sure everything is lined up before actually drilling. This row of the skins is match drilled, not the ribs though. After successfully conquering that moved on to match drilling the rest of the skins to the understructure. Worked from the center spar/rib intersection outwards, with clecoes in every hole. Probably not required but want to make sure it's nice and straight.
