Align your metal bed frame and your iron headboard. Decide on a spot where the pieces will be attached for the most stability. Make a mark with chalk on the iron headboard.
Position the headboard plate adapter so the cast iron headboard, frame and adapter line up properly.
Loosely attach the plate adapter to the metal bed frame with a socket wrench. Leave some slack between the frame and adapter. Repeat on the other side.
Loosely attach the plate adapter to the metal bed frame with a socket wrench. Leave some slack between the frame and adapter. Repeat on the other side.
Put on safety goggles. Fit your drill with a metal cutting drill bit. Drill a hole through the chalk mark in the headboard. Repeat on the other side of the headboard.
Attach the adapter plate to the iron headboard through the drilled holes with thread cutting screws. Tapping screws will keep the screw locked tightly in place in the iron headboard.
Tighten the fit of the adapter plate and the metal frame with the socket wrench.