Drilled and countersunk seven 1/4" holes in the bottom plate for attachment to the work table edge. Looks like I'm going to need larger flat head screws than the #10x1-1/2" originally purchased for this job. Also noticed that the bottom plate has a slight bow along the 90 degree hinge-edge. Therefore I'm not going to match drill the top plate to the bottom plate with 3/8" holes until after the bottom plate and bend plate have been joined via the hinges. This should true up the bottom plate so that it parallels the bending edge of the top plate.