Fit together the notches on the A and B legs for one side of the cart. Drill a centered ¼-inch hole through both legs at the notched intersection. Slip the post end of a 5⁄8-inch screw post through the notch hole in the B leg. Lay the legs on a work surface, A leg facing up, and slip the screw end of the screw post into the notch hole in the A leg. Begin screwing it into the post by hand, then tighten with a screwdriver. Repeat for the second side of the cart.