How to Drill a Hole in Galvanized Metalby C.L. Rease
Whether you are fastening a screw or running a line through metal, at some point, you will need to drill a hole through a galvanized metal panel. Drilling into galvanized metal is no different than drilling a hole in standard carbon metal, with the exception that the protective zinc coating does not protect the drilled hole. This can cause corrosion (rust) to form in and around the hole. After you drill the hole, it is possible to provide adequate corrosion protection for the drilled hole.
Put on your safety glasses. Place the point of the center punch onto the galvanized metal, where you need to place the hole. Hit the back of the center punch with the hammer to create a depression referred to as a center mark. The center mark keeps the drill bit from wandering away from the location that you need to drill.
Insert the proper size drill bit into the drill motor. Start with a smaller drill bit to create a pilot hole if you are drilling a large diameter hole in the galvanized metal.
Apply cutting fluid to the drill bit to reduce the friction caused during the drilling process. This will keep your drill bit from becoming dull. Align the tip of the drill bit with the center mark that you made on the galvanized metal in step 1. Place the tip of the drill bit into the center mark.
Place pressure on the drill motor. Depress the trigger of the drill motor to start drilling. Pump the drill's trigger to keep the speed of the drill bit down to reduce heat build up at the drill bit. Ease up the pressure that you have on the drill when you reach the exit side of the hole.
Attach the flapper wheel to the grinder. Make sure that your safety glasses are on and remove the bur from both sides of the galvanized metal with the grinder. Wipe the area clean with a rag. Make sure that the area surrounding the hole is free of dirt and metal filings.
Shake the spray can of cold galvanizing for 30 seconds to mix the can's contents thoroughly. Remove the cap of the spray can. Hold the can 8 to 12 inches away from the surface of the metal. Coat the hole and the area around the hole with a thin layer of galvanizing spray. Repeat the procedure for the other side of the hole that you drilled in the galvanized metal.
Allow the galvanizing spray to cure before you use the hole, to provide full protection against rust.