Drilling a hole through a piece of glass might sound like a recipe for disaster, but it's actually a manageable project to do it yourself. You can use a conventional home drill for this job, but you will need to purchase one or more specialty bits. It is also important to prepare the glass for cutting, run the drill at a low speed, and keep the glass cool with the help of water. With a little planning and patience, you'll get your job done without breaking the glass!
Part 1 of 2: Setting yourself up for success
Step 1. Take safety seriously by putting on the proper protective gear
When done properly, drilling through glass is usually safe, but don't play it! Put on a protective visor to protect your eyes from any glass that could break. Likewise, wear a mask, sturdy work gloves, a heavy fabric long-sleeved shirt, long work pants, and work boots.
If it is a one-time task, you can fix it with a typical mask. However you will be drilling multiple holes, be sure to use a NIOSH approved N95 mask. The dust that comes out of drilling into glass, called silica dust, can cause a type of lung cancer known as silicosis
Step 2. Inspect the glass for damage and confirm that it is not tempered glass
Don't try to make a hole less than 3/4 inch from the edge of the piece of glass, and keep at least the same distance from any cracks, nicks, or nicks. In fact, an even better distance is 2 inches (5 cm). Check the glass carefully to confirm that there is no damage to the area to be drilled.
When you are checking the glass, please confirm that you are not trying to drill tempered glass. This type of glass is designed to break into small pieces (rather than knife-like shards) when impacted, so it's not good for drilling! Tempered glass always has a mark indicating it, usually in the corner or along one of the sides
Step 3. Insert a small drill bit made for glass and earthenware into a variable speed drill
Glass and earthenware bits have a lance-shaped tip made of carbide or diamond and can be found at any retail home improvement store. Insert a 1/8 inch (3 mm) bit into the drill to get started, even if you plan to drill a larger diameter hole. Starting with a small pilot hole decreases the chances of breaking the glass.
Most cordless or corded drills are suitable for this task, as long as they have a variable speed setting that goes below 400 RPM (revolutions per minute). Please refer to the product guide to confirm the low speed RPM setting for your drill
Step 4. Place padding on the table if you are cutting flat glass
The best way to cut through a flat piece of glass is to place it on a flat table. However, be sure to put some padding between the glass and the table! A thick towel or an old sheet are good options, but a small sheet of bubble wrap will also do the trick.
If you are using a surface you want to protect, spread a sheet of chipboard or plywood under the padding. This way, you won't accidentally drill into the tabletop
Step 5. Create a padded "nest" in a bowl if you are cutting curved glass
Drilling a hole in a bottle (or other curved piece of glass) is basically the same as drilling flat glass, with one exception. Instead of spreading it on flat glass, nest it by putting it in a bowl, like a baby in a basket. Surround it with padding so that it is securely in place at an angle of about 45 degrees to the table the bowl is on.
Step 6. Secure masking tape or thin cardboard over the point where you want to drill
For a faster option, create an "X" shape with two strips of masking tape. For more protection against tearing, cut a 2 to 3-inch (5 to 8 cm) square of thin cardboard (such as a tissue box or cereal box) and tape it over the hole where you are going to drill with masking tape..
- In either case, use a mark to create a small "X" where you want to put the tip of the drill bit.
- Using tape or cardboard reduces the chance that the glass surface will break as soon as you start drilling. It also reduces the chances that the bit will “jump” or “walk” on the glass surface when you start the drill.
Step 7. Apply water to the area to keep it cool throughout the process
If you don't keep the glass cool while you pierce it, it will heat up from friction and be more likely to break. Although you can use oil or lubricant as a coolant, water works quite well. Use one of these methods, the first one is probably the simplest:
- Fill a plastic spray bottle with cold tap water. Spray the area you just marked several times well to get it wet. Once you start drilling, re-spray the area frequently, probably every 5 to 10 seconds, so that it remains wet and cool.
- Fill a large plastic soda or milk bottle with water, then poke a hole in the side, near the bottom. Position it so that a thin stream of water falls on the cutting area continuously.
- Form a ring in the shape of a plumbing caulk thread and use it to make a “well” around the cut area. Keep it filled with about 1/2 inch (2.5 cm) of water throughout the process.
Part 2 of 2: Drilling the hole
Step 1. Make the tip of the bit touch the drill point at a 90 degree angle
For a flat piece of glass on a flat table, the bit should be completely vertical. Place your free (gloved) hand outstretched on the glass, using light, even pressure to hold the glass in place. Make sure your free hand is 4 to 6 inches (10 to 15 cm) from the piercing point.
For a glass bottle that is nested at a 45-degree angle, make sure the drill is positioned perpendicular (90 degrees) to the surface of the bottle, not the tabletop. Use your free hand for support and keep it 4 to 6 inches (10 to 15 cm) away from the piercing point
Step 2. Run the drill at less than 400 RPM and press it in slowly
It starts drilling at the lowest possible speed in 2-3 strokes, just until it passes through the cardboard or tape and makes contact with the glass. Make 2 to 3 more pulses on the lowest speed until you start etching the glass. Then run the drill at a slightly higher speed for about 5 seconds.
- Don't forget to keep the area cool - at this point and throughout the process! If you're using a water spray bottle, spray the area every 5 to 10 seconds.
- The drill probably doesn't have a reading that tells you it's running at 400 RPM (or any different speed). In that case, use your ear! If, for example, the drill runs up to 1000 RPM, press the trigger until the drill sounds like it's running at almost half its maximum speed to estimate 400 RPM.
Step 3. Remove the tape or cardboard after making a “hole” in the glass
Once you've gone through the tape or cardboard and started cutting the glass, stop for a moment and remove the covering material. Quickly check the glass and confirm that you have made a small "hole" in it.
- If you are using a water spray bottle, thoroughly spray the area again before continuing.
- If you see any breakage in the glass around the hole, stop the drilling process. If you continue, the glass will almost certainly break.
Step 4. Start the drill at 400 RPM until you have made a hole through the glass
Place the drill in the hole and start it at the lowest speed and slowly increase it until you reach 400 RPM. Maintain this speed until you feel that the bit has completely pierced the glass. Once that's done, lift the drill up and out of the way.
If you're using a stream or water “well,” keep drilling continuously at 400 RPM until you've pierced the glass. If you have to spray more water, every 5 to 10 seconds, stop the drill, lift and remove it, spray the water, turn the drill back, and turn it back up to 400 RPM
Step 5. Switch to a larger drill and use it to enlarge the hole as desired
If you started with a 1/8-inch diameter drill bit and don't need a larger hole, skip this part! Otherwise, switch to a larger glass and earthenware bit that does not exceed a diameter of more than 1/4 inch (6 mm). For example, go from a 1/8 inch (3 mm) bit to a 3/8 inch (9 mm) bit.
- Once you've switched to the larger bit, follow the same process as before to enlarge the hole. Make sure to keep adding water!
- If the hole is still not large enough, switch to an even larger bit, again, without increasing the diameter by more than 1/4-inch (3mm).
Step 6. Smooth the hole with a diamond file and rinse off any glass powder
Once the hole is complete and the size to your liking, check the glass again to see if there are any cracks. If there aren't, take a diamond file and carefully scrape the ragged edges around the perimeter of the hole. If you are working on a flat sheet of glass, carefully lift it up and file the back as well. Use a stream of water to rinse off any remaining glass dust.
If you plan to thread a thread through the hole, to hang a small mirror, for example, buy a rubber grommet at the hardware store and press it into the hole. The flexible rubber grommet in the form of a thread, which can be matched to the size of the drilled hole, will reduce wear on the thread
- In addition to increasing the likelihood of breaking glass, running the drill at high speed dulls the bit and could ruin it much more quickly.
- Use a sequence of bits, starting with smaller ones and gradually increasing the size, to minimize pressure on the glass.
- The bit will probably generate small chips around the hole in the back, but it will create a cleaner hole in the front. So, drill into the displayed side of the glass - the side you want people to see!
- Instead of a drill, you can use a drill press if you have one available. It can help regulate bit pressure.
- Glass is brittle and sharp. Handle it carefully, with gloves, and wear a respirator and protective goggles when drilling.
- Glass splinters can be very dangerous to the eyes, wear suitable ANSI protective goggles.