I drilled through the rack and the rail it was to sit on. The hole in the rail was large enough for a #2 machine screw to fit through. The hole in the rack was smaller and then threaded for a #2 screw. Then I screwed the rack to the rail from underneath. If the screw was too long, I shortened it so it would not interfere with the spur gear, but was long enough to be held in place. My racks are 12 inches long and are held by four screws each. It works fine.