Scarffed cornert of LH top wing skins where they overlap. Overdid filing for scarf joint and the skin got too thin on the edge. Filed a releif notch in the area where it was too thin to prevent a crack from forming. Scuffed and cleaned both LH top wing skins. Dimpled LH top wing skins and wing walk skins. Primed wing walk skin. Fabricated a holding tool from hardwood for aligning the bucking bar when setting the spar to LE rib rivets.
