How to drill a hole in a glass?

Drilling through glass is only necessary if it’s either required for you to complete a specific project or if certain designs incorporate glass. Sometimes glass needs to be drilled to run ducting through windows. 

Another good example would be glass furniture – modern living room tables made of glass slabs are often drilled at the edges to make room for fasteners that would hold the legs and connect corners.

What to expect when drilling holes in glass?

Drilling glass is not as simple as drilling wood or metal. While glass is technically a hard material, it’s also very brittle, making it prone to breaking/shattering. If you want to drill holes in glass blocks or sheets, you’ll need to prepare the right tools and keep in mind the following:

• Never attempt to drill through Tempered or safety glass (It will just shatter). You can drill through flat and curved glass surfaces, provided you know the right technique. 
• Use either carbide-tipped or diamond drill bits [1]. They have better geometry for drilling through the glass and also reduce friction. 
• Use lower speeds when drilling. You’ll want to keep the drill site cool at all times. Spray water after every successful drill and keep temperatures within 55-69⁰F(21-29⁰C) as much as possible.
• Lowering drill speeds also reduces vibration, thus lowering the chance of shattering the glass. 

What are the types of glass?

• Annealed glass. Also called float glass, annealed glass is hot glass products that are slowly subjected to cooling after they’ve been formed. Annealing is said to greatly reduce the internal stresses in the glass, making it among the most common and affordable glass types. After annealing, glass can easily be cut, polished, and drilled.
• Heat-strengthened glass. Heat-strengthened glass undergoes the same heating process as tempered glass but is subjected to slower cooling, resulting in lower surface compression. It’s not as strong as tempered glass but is more durable than annealed glass. It’s an in-between of annealed and tempered glass. Can be drilled through.
• Tempered glass. Also called safety or reinforced glass, tempered glass is made by heating glass up to 1200⁰F(650⁰C) then immediately cooling it, creating more surface compression, making it harder and more resistant to shock. Once the glass is tempered, unless fabricated beforehand, it can no longer be cut or drilled as doing so will shatter the glass.

• Laminated glass. Laminated or layered glass is a glass product created via the permanent bonding of the internal layers of two plies of glass. This process of “Lamination” supports the entire glass structure, creating a strong, seamless, and uniform layer even when broken. Like annealed glass, laminated glass can easily be fabricated and drilled.
• Coated glass. Industrial glass products are sprayed with metal oxides to form a thin solar resistance layer. Coated glass is utilized in specialized applications because of its quality that modifies their behavior when exposed to solar radiation. These can technically be drilled through, but extra care must be taken so as not to compromise the thin layer of coating (such as drilling from both sides).
• Acid-etched. Annealed glass has been treated with hydrofluoric acid to achieve a frosted look. This type of glass is low-visibility, making it perfect for areas that require privacy, such as bathrooms and “executive offices.” Drills just as easily as annealed glass.
• Low-iron glass. Also known as extra clear glass, these glass products are the choice for when glass needs to appear seamless. Perfect applications would be as markerboards or as glass dividers. This type of glass is clear glass with around 5-6% more light transparency and almost no tint. Since this is a softer kind of glass, drill with a little more speed, but also with more precision.

• Decorative glass. Also called ornamental glass, decorative glass is more aesthetic than it is functional. These are some of the most visually pleasing glass available as they can heavily impact the look and atmosphere of an entire room. Since decorative glass comes in various sizes and thicknesses, it can be drilled but at different speeds.
• Insulated glass (Double glazed). Insulated glass consists of two glass panes separated by a space in between that create a gas-filled vacuum which helps facilitate thermal fluctuation in parts of the building where thermal glass is installed. While thermal glass can be drilled technically, it’s not recommended as the air-tight seal will become broken.  Instead, you should get the holes drilled and sealed at the manufacturer before assembly as the air-tight seal for the gas is required for them to work.

Tools to use for drilling holes in a glass

• Dremel. A famous American brand, the Dremel also happens to be a rotary tool that relies on high speeds. With the right Dremel bit or burr to drill holes in glass, it can drill, grind, sharpen, cut, sand, and more. 
• Drill. Whether by hand or power, you’ll need a drill if you want to bore through the glass. It’s recommended that you go with power brushless drills since it’s easier to control and maintain performance with variable speed.
• Drill bit. You’ll need appropriate drill bits when drilling through glass. Remember that carbide-tipped and diamond bits are designed to go through hard yet brittle material.

Other things you might need when drilling glass

• Lubricant. Lubricants help control temperature and keep the drilling surface smooth, reducing friction and the likelihood of cracking. Water and mineral oil do pretty well.
• Gloves. Drilling through glass is likely to produce some glass dust. Wear gloves to protect your skin from irritation and accidental glass splinters.
• Goggles. The same can be said for your eyes – goggles will protect your eyes from the dangers of small flying glass debris.
• Mask. Inhaling glass dust can be very harmful and dangerous. Besides causing coughing from irritation, microscopic glass bits can become embedded internally, possibly causing chronic ailments.
• Clamp. These are always essential whenever you need to secure and stabilize a workpiece. Always clamp vertically, never horizontally as glass is more likely to break that way.

How to drill a hole in a glass without shattering?

1. Mark where you want to drill. You can use felt tip markers or masking tape to create an “x” to indicate the center. Using masking tape also adds traction, making the glass surface less slippery. 
2. Secure the workpiece. You’ll want to cushion flat pieces such as panes, while slightly angling (45⁰) curved ones such as when you’re drilling holes in glass bottles and jars. 
3. Use either a ⅛” or 3/32” diamond drill bit.
4. Put on the necessary protective equipment and hold the drill completely perpendicular to the workpiece.
5. Begin drilling at around 400 RPM. This is great for starter holes. Gradually increase speed if needed/once you get through the initial surface.
6. Remember to properly lube and quench the workpiece as continuous drilling easily heats up the glass, potentially causing it to crack or shatter. 
7. If larger holes are needed, use smaller bits to create starter holes, then swap them out later for larger ones.
8. File the holes to make them smooth and safe. 

Here are more drilling tips to refer to.

How to drill a hole in a glass using a Dremel?

1. Mark or identify where you want to drill. Since a Dremel is a smaller tool compared to a power drill, it’s also easier to work with smaller holes in glass pieces. 
2. Use a diamond drill bit. Use sizes compatible with your Dremel tool.
3. Have something to stabilize and hold the workpiece. Small wooden blocks will do fine here.
4. Submerge the workpiece first in a small container or basin. This acts as a douser that prevents heat build-up. 
5. Select a low-speed setting and begin drilling by coming in slightly at an angle. Once you feel like you’ve breached the surface, slowly bring the drill up to vertical. 
6. Work in a circular motion all throughout. Drilling bigger holes without having to change bits also make use of this technique. Simply select a slightly higher speed and add a little more pressure as you move the tool in a circle. 
7. File (if needed) and wipe dry.

Here’s more to know about the Dremel tool.

How to drill a hole in a glass using a hole saw attachment?

A hole saw attachment or ‘core’ drill bit is basically just an alternative drill bit for larger holes.

The techniques to drill with a hole saw don’t really differ that much from using a power drill or Dremel tool with standard diamond drill bits.

Instead, keep these tips in mind:

• Make sure that your core drill bits are diamond-tipped. 
• Much like using a Dremel tool, cushion the piece with a block of wood.
• Fully/partially submerge the piece in water, depending on your experience and if the workpiece is flat or rounded.
• Come in at an angle and slowly bring it to vertical from all angles in a circular motion to start with. Don’t lose the slow, circular motion. 

Tips in drilling holes in glass fish tanks

• You can drill an empty, assembled aquarium, or individual panes if you know how to drill through the glass. 
• Always measure the diameter of fixtures you want to install (E.G bulkheads, etc/). This helps determine the size of the drill hole. 
• Keep in mind the exact glass material of your aquarium. 
• Create a dam using some putty. This will help guide the bit and keep you on-point when drilling. 
• Drilling near a pane’s base and corners are easier.

Tips for drilling holes in glass beads

• Embed the bead into some putty with the side you intend to drill face up.
• Determine the size of the hole and mark.
• Submerge in water. This will serve as a lubricant and cooling agent.
• Use carbide-tipped or diamond drill bits. Touch the tip against the bead and continue slowly until the desired result. 

Tips for drilling holes in wine glasses and jars

• Better to drill at points nearer the edge and base as they’re often sturdier. 
• Remember to use the appropriate bits.
• Recommended using a starter bit. 
• Secure workpieces on cushioned material.
• Remember to file the edges of the holes to keep them safe. 

Should you drill holes in tempered glass?

Unless it’s an emergency, you should never drill tempered glass. And it requires a carefully executed technique [2].

In fact, unless it’s a life or death situation, you should never tamper with tempered glass because it’s designed to break at the slightest hint of structural damage to prevent further injury.

Things to do after drilling a hole in  a glass

Successfully drilling holes doesn’t simply end there. While drilling makes up the brunt of the work, a couple of things post-drilling is what completes the task. Remember these things to ensure that your project is both successful and clean:

• Especially for larger holes, remember to sand or file them down to remove jags and sharp edges. 
• Always clean up the work area. Dust off both the surface as well as the tools and drill bits. 
• Properly dispose of waste and trash. Recommended to use thick plastic bags

Dos and don’ts when drilling holes in a glass

Dos

• Do only use diamond drill bits.
• Do remember to properly lubricate and cool the workpiece to avoid shattering. 
• Do remember to stick mainly to lower speed settings when using power tools.

Don’ts

• Don’t use regular drill bits as they are not designed for brittle material.
• Don’t just continuously drill as this will generate friction and heat, potentially causing cracking or worse. 
• Don’t just come indirectly at the workpiece. Initially drill at an angle and slowly work your way up to vertical. This reduces stress and tension on the glass, preventing damage.

Conclusion

Though drilling glass may seem challenging, it’s more technical than it is complex – it’s not really hard, but it can be tricky. Though there are few cases where drilling glass is a necessity, knowing how to successfully do so will save you a lot of resources. 

Extra glass fabrication services can be expensive, especially when piled up, so having the knowledge to do it yourself increases both productivity and finances.