If you own a drill, one day you’ll want to bore a hole in metal: From making L-brackets to mounting gear onto an aluminum boat, drilling metal safely and effectively is a skill every cottager should master.
1. Mark the hole and dent its location with a centre punch and hammer. (No punch handy? A nail works in a pinch.) That little divot keeps the bit from wandering all over your piece.
2. Clamp the piece to a bench. Never try to hand-hold it; the metal will likely “grab” the bit and become a spinning blade of terror. For clean holes in thin material, such as sheet metal, clamp between two plywood scraps and drill this sandwich.
3. Choose a bit rated for the metal you’re drilling, then go slowly. High speeds mean high temperatures, and heat will quickly destroy even a top-quality bit. Add a little lubricant to the hole: Although thread-cutting oil is best, I often use motor oil. Even WD-40 is better than no lube at all.
4. De-burr. This is a fancy term for smoothing the rough edge you get when drilling metal. A metal file works, or you can use, carefully, a very large drill bit to lightly chamfer the holes.