Hold a steel bracket up against the legs and frame of the futon, and mark where the holes of the bracket line up with a pencil or pen.
Place a drop of lubricating oil onto each of the pencil or pen marks. This helps lubricate the drill bit when you drill and prevents overheating.
Drill through each pen or pencil marking using a cobalt bit, which is specifically designed for drilling through metal. Use a slower drill speed for best results.
Realign the brackets and screw them into position on the legs and along the frame. They help prevent the futon from buckling or breaking.