Stick a piece of masking tape over the area where you want the hole, to prevent the drill bit from wandering when you start it. Mark the precise center of the hole on the tape.
Hold the sharp point of a small nail against the mark and tap the nail with a hammer to make a slight dent, to help keep the drill in place.
Insert a 1/8-inch cobalt or titanium drill bit in an electric drill. Put on safety goggles and hearing protection. Drill through the sink at the mark, using the masking tape and dent to keep the drill from wandering.
Replace the 1/8-inch bit with a 1/4-inch bit and drill through the same hole to enlarge it. Repeat with a bit that's 1/8-inch larger than the previous one until you reach the size you need. If you have a step drill, use it instead to drill the series of holes at once. A step drill is a roughly cone-shaped bit that allows you to drill gradually larger holes without needing to change the bit each time.
Insert a small round file into the hole and file the edges larger, if you need a hole slightly larger than the size of the final drill bit.
Vacuum up the remaining particles of metal dust around the hole, or wipe them up with a damp paper towel.
Things You Will Need
- Masking tape
- Titanium or cobalt drill bits
- Electric drill
- Eye and hearing protection
- Vacuum or damp paper towel
- Add a drop of oil to the area you're drilling to reduce friction, and drill at low speed.