Drilling a hole in glass is tricky business. Not only do you risk breaking the glass, but you also risk personal injury. But certain DIY projects and crafts call for this skill, and whether you’re hanging a frameless mirror or creating a custom light shade, you’ll be glad you’ve mastered it.
Follow these step-by-step instructions to get a hole where you want it, without breaking the glass.
What to Know Before You Begin Drilling Through Glass
Read these tips before picking up that drill.
Drilling into glass too quickly can generate heat that will damage the bit. Check the settings on your variable speed drill for its range. The label should say something like “0-1500 rpm.” If you fully depress the trigger, it will turn 1,500 rotations per minute.
Squeezing the trigger only halfway causes it to turn at 750 rpm. Release it a bit more and you have 375 rpm. Experiment with this and you’ll be able to guess the speed of the drill by the sound of the motor and how it feels in your hand.
Drill bits suitable for glass, tile, and other hard surfaces have spear-shaped carbide or diamond tips. They come in a variety of sizes. Purchase a small one, about ⅛-3/32-inch, for starting the holes and others the sizes of holes you wish to create.
To lessen the build-up of heat and dust while drilling, experts recommend applying a drop or two of lubricating oil to the glass. Any type of oil will work. If you’re working on a vertical surface, use a bit of plumber’s putty or modeling clay to keep the oil from running.
Secure the glass so it doesn’t slide around. Lay a pane on a flat, cushioned surface or rubber pad. Use a clamp to secure a bottle or other round object to the workbench or use a vise. Also, always wear your personal protective equipment when drilling.
Since practice makes perfect, try drilling a few practice holes in glass similar to the project you’re working on. And never try to drill through tempered or safety glass. It’s designed to shatter on impact.
TIP: You can tell the difference between tempered glass and annealed, or regular plate, glass with the following tests:
- Tempered glass has smooth, even edges. The edges of other glass are rough to the touch.
- You can see dark streaks in tempered glass when viewed in the sunlight through polarized glasses.
- When you look closely, you can see small imperfections in tempered glass.
- Scoring produces a clean line on annealed glass. On tempered, scoring leaves flakes and bumps.
- If you have a full sheet, check the corners for a small stamp that indicates that the glass is tempered.
How to Drill Through Glass
- Secure the glass object you plan to drill.
- Tape an X over the area you want to drill using masking or painter’s tape. The tape will keep the drill bit from drifting on the smooth surface.
- Measure and mark the spot for the hole on the tape using a permanent marker. To prevent the glass from cracking, stay at least ¾-inch from the edge of a pane.
- Add a drop of the lubricating oil.
- Using a ⅛- to 3/32-inch bit, drill a pilot hole into the glass, applying only the slightest pressure with the drill. Too much pressure will crack the glass.
- Once the pilot hole is started, remove the tape and switch the drill bit for one the size of the hole you wish to create.
- Continue to drill at a low speed, about 400 rpm, maintaining a light pressure. Periodically stop to clean away the dust and add oil as needed.
- The bit will create a smooth, clean hole where it enters and a sharp hole with little chipped places where it exits the glass. For this reason, once you’re ¾ of the way through, turn the glass over. Repeat the process from the opposite side.
- Use the sandpaper or file to smooth any rough edges.