How to Drill a Hole Into a Cast Iron Sink

For the homeowner who wants a heavy and durable sink, you can't beat a cast iron sink. In addition to its durability, this sink typically comes with a ceramic coating that gives you not only a smooth finish but a colored one that will match your other kitchen appliances. If there is a disadvantage to these sinks it is that adding special fittings like spray hoses can be a major challenge if the fitting requires a hole to be drilled through the sink surface. But if you have the right tools and technique it not not be beyond your capabilities. Here's how to drill your hole:

Things you'll need:

  • Cast iron sink
  • Permanent marker
  • Masking tape
  • Variable speed drill
  • ¼" drill bit
  • Small paintbrush
  • Carbide diamond bit
  • Round metal file
  • Lubricating oil or container of water

Step 1 – Locate the Hole

If you're cutting a hole for a faucet, your hole will probably be located in the center of the sink's rear surface. For faucet knobs, each hole will be positioned on the opposite side from the other knob, each placed about 3 inches out from the faucet. Identify the spot where you want your holes, stick a small piece of masking tape on that spot. It will keep the drill bit from skipping across the sink's surface when you begin to drill. Finally, use your permanent marker to place a dot on the making tape.

Step 2 – Preparing to Drill

Insert your porcelain bit into your drill chuck and tighten the chuck. Be sure it is tight. Place a drop of oil on the tip end of your bit to keep it the friction from burning it when you begin drilling. If you don't have lubricating oil, have a container of cool water handy to dip the bit in when it becomes hot as you drill. Finally, wear goggles or other glasses to protect your eyes from flying bits of metal.

Step 3 – Drilling Your Hole

Begin drilling slowly, the point of your porcelain bit on the dot you marked on the masking tape. Hold the drill so that the bit is as nearly vertical as possible while it is turning. The first bit will drill through the porcelain only. Then, it will stop discontinue making a hole when it comes to the iron. At that point, you'll need to stop the drill, remove the porcelain fiber debris with your paintbrush. Replace the bit with the carbide drill, but in doing so, be sure you cool the porcelain bit before removing it. Then, begin drilling again as you did with the first bit. Continue drilling, stopping every few seconds to cool your bit with lubricating oil, or dip your bit into the water from the water container. Be careful when doing this that you do not touch the hot bit. Continue with this process until you have drilled through the cast iron.

Step 4 – Finishing

When you have drilled your first hole and you need to drill others, use the same process and the same bits. When finished with making your holes, use a round metal file to smooth the edges of the holes you made