Drilling a hole in a pane of glass or a mirror is simple. The key is to use a carbide bit made especially for glass, sea glass, wine bottles, glass block, tile, stone, granite and marble. You’ll find these bits at most home centers alongside other drill bits or ceramic tile tools.
Because glass is extremely smooth and hard, the bit will want to wander as you start drilling. To give the bit a foothold, tape a small scrap of dense cardboard (like cereal box cardboard) to the glass. Use less pressure! Let your drill bit drill at its own pace. Begin at very low rpm to create a dimple in the glass, then remove the cardboard and continue at about 400 rpm. Use enough lubrication/coolant to keep the bit cooling and the hole clean. If you’re drilling on a horizontal surface, you can pour a little oil on the area.
Make sure the glass is firmly supported on the backside and place only very light pressure on the drill; press too hard and you’ll crack the glass. The bit creates a clean hole on the side it enters, but usually chips the edges of the hole on the other side.
Note: You can’t drill tempered glass.
Drilling glass, tile, or stone? All you need is the right diamond drill bit and a few helpful hints to have your project turn out beautifully.