Can You Drill a Hole in Glass or Ceramic? Yes, With the Right Bit and Speed

The short version by material

Each of these materials is hard or brittle in its own way, so each wants a slightly different approach. Glass and glazed ceramic are hard and crack under heat and pressure. Terracotta is softer but chips around the hole. Plexiglass, which is acrylic, is not hard at all, but it cracks when the bit grabs or the plastic gets hot.

The table below sums up what to reach for. Details for each follow in the sections after it.

Drilling glass

Plain annealed glass, like a bottle, jar, picture frame glass or an old window pane, can be drilled at home. Use a bit made for glass: a spear-point carbide bit for small holes, or a diamond-coated bit or hole saw for larger ones. A standard metal or wood bit will skid, overheat and often crack the glass.

Do not try to drill tempered glass. You can usually spot it by a small etched stamp in one corner. Tempered glass is under internal stress, and drilling it makes the whole pane break into small pieces. Laminated windshield-type glass is also a poor candidate. If you need a hole in tempered glass, a glass shop has to make it before the glass is tempered.

Drilling ceramic, tile and terracotta pots

Glazed ceramic has a very hard outer skin. Start with a diamond or carbide tile bit and a slow speed. Let the bit wear through the glaze before you add any pressure. Once the glaze is cut, the clay beneath is much easier.

A terracotta pot is the friendliest of the group. It is porous and softer than glazed ceramic, so a masonry bit or tile bit works well. Drill from the outside, keep the pot supported on a towel or scrap board, and ease off as the bit breaks through the inside wall. That last moment is when chips and cracks happen.

Thin or old pots, and pots with cracks, are riskier. If you can see hairline cracks, expect the pot to split. Practice on a spare pot or a broken piece first if you can.

Drilling plexiglass

Acrylic sheet is easy to drill but easy to ruin. A bit with an aggressive wood-style tip can grab and crack the sheet. A sharp twist bit, ideally one ground for plastics, or a step bit, gives a cleaner hole. Run the drill at a moderate speed with light pressure and back the bit out now and then to clear the shavings.

Leave the protective film on while you drill if the sheet has it, and clamp the sheet over a scrap of wood. If the plastic starts to melt or gum up on the bit, you are going too fast or pressing too long. Stop, let it cool and continue.

Step by step: a safe way to drill any of these

This routine works for glass, ceramic and terracotta, with small changes for acrylic.

• Put on safety glasses. Fragments and glass dust can fly. Add gloves and a dust mask for ceramic and terracotta dust.
• Mark the spot with a marker, then put a piece of masking tape over it. The tape gives the bit something to bite into and helps stop skidding.
• Lay the piece flat on a soft, stable surface such as a folded towel over plywood. Clamp it if you can.
• Build a small dam of plumber's putty or modeling clay around the mark and add a little water. Keep water away from the drill body and the battery.
• Set the drill to its lowest speed and turn hammer mode off. Start at a slight angle, then straighten up once the bit has made a small groove.
• Use light, steady pressure and let the bit do the work. Lift the bit every few seconds to let water reach the cut.
• Ease off when you feel the bit about to break through. Finish gently, and sand or file any sharp glass or ceramic edges.

What to look for in a drill

Almost any cordless drill can do this job, because the material matters more than the power. What helps is slow, controllable speed. Look at the low-speed range on the spec sheet. For example, the DEKOPRO lists a low range of 0 to 350 rpm, the PULITUO lists 0 to 400 rpm, and the DEWALT DCD771C2 lists 0 to 450 rpm. The AVID POWER tops out at 550 rpm, so it stays gentle across its whole range.

Fine clutch control and variable-speed triggers also help you start slowly. A drill with a 3/8 in chuck, like the AVID POWER, is plenty for small glass and tile bits. If you want to use larger diamond hole saws, a 1/2 in chuck gives you more bit choices. Our best drill comparison lays out chuck size, speed, torque settings and weight side by side.

Be careful with hammer drills. The DEWALT DCD806B, for instance, is a hammer drill with a high-speed gear that reaches 2000 rpm. That is a great tool for other jobs, but on glass or ceramic you need hammer mode off and the low-speed gear selected. Hammering action breaks glass and cracks pots.

Common mistakes and how to avoid them

Most cracked pieces come from heat, pressure or speed. Keep these in mind before you start, and check the best drill page if you are shopping for a more controllable tool.

• Using a regular twist bit on glass or glazed ceramic.
• Running the drill at full speed.
• Pushing hard instead of letting the bit cut.
• Drilling too close to an edge. Stay well back from edges and corners.
• Letting the bit run dry, so the glass overheats.
• Forgetting to turn hammer mode off.

Safety notes

Always wear eye protection, since glass and ceramic can throw sharp chips. Wear gloves when handling broken or freshly cut edges, and a dust mask when drilling ceramic or terracotta. Fine dust from drilling is not something to breathe in.

Water and electricity do not mix. A cordless drill removes the cord hazard, but you should still keep water away from the battery and the tool body. Use only small amounts of water and wipe up spills quickly. If you are working at a window, a mirror or a shelf at height, secure the piece and the ladder first, because a dropped sheet of glass is dangerous.

Frequently asked questions

Do I need a special bit to drill glass?

Yes. A spear-point carbide bit or a diamond-coated bit is made for glass. Regular bits for wood or metal tend to skid and can crack the glass.

Can I drill a hole in a flowerpot for drainage?

Yes. Terracotta and most ceramic pots can be drilled with a masonry or tile bit at low speed. Drill from the outside and ease off as the bit breaks through.

Why did my plexiglass crack?

It was most likely too much speed, pressure or heat, or the bit caught as it broke through. Use a sharp bit, clamp the sheet over scrap wood and go slowly.

How do I keep the bit from sliding at the start?

Put masking tape over the mark and start at a slight angle at a very low speed. Once a small groove forms, bring the drill upright.

Is it safe to drill tempered glass?

No. Tempered glass breaks into many small pieces when drilled. Holes must be made before the glass is tempered.