Steel doors are known for their strength and durability, but one wrong move with a drill can leave an ugly hole in your door. Fortunately these holes are fairly easy to patch and repair using epoxy resin fillers designed for automotive bodies. The resin fills the hole, and the surface can be refinished to blend in with the rest of the door. This simple repair process can restore your door and save you the expense of buying and installing a brand new door and frame.
Remove the door from the frame by unscrewing the hinges. You can also use a hammer and nail to pop the pin out from the hinges, but not all hinges have this feature. Place the door on a pair of sawhorses so that you can access the holes.
Insert a wire wheel bit into your drill and use it to remove the paint and primer from around the hole. Make sure to remove all paint from cracks or dents around the holes as well. Clean the door well with a damp cloth before proceeding.
Mix the Bondo or filler. Place a small amount of resin onto a piece of scrap wood then add the hardener. Blend them according to the instructions on the package, making sure to mix them thoroughly. Work quickly as Bondo tends to harden within minutes.
Spread the Bondo over the hole in your door using a putty knife. If the hole is very large, add some duct tape inside the opening to hold the Bondo in place as it dries. The Bondo should be spread past the edges of the hole so that you can sand and blend the patched area to match the rest of the door.
Wait until the patch is completely dry, then sand it by hand until it is smooth and even with the surrounding door surface. Clean away sanding dust and add a coat of rust-inhibiting primer to the patched area.
Paint over the dried Bondo to match the rest of the door. This works best on relatively new doors that have not faded over time. On older doors, you'll usually get the best results by repainting the entire door.
Reattach the hinges and rehang the door to complete the project.