The best drill bit for tempered glass is a diamond-coated drill bit. Because tempered glass is highly stressed and designed to shatter into tiny pieces upon impact, standard carbide bits will not work. Diamond bits provide the necessary hardness and cutting precision to bore through without causing cracks.
Set the drill to a slow speed. Too high a speed can generate excessive heat, increasing the risk of cracking. Start piercing slowly and steadily. Apply light, consistent pressure, allowing the tip of the drill bit to gradually penetrate the glass.
The best drill bit for glass is a diamond-coated hole saw (for larger holes) or a spear-point carbide-tipped bit (for smaller holes). Standard bits will shatter glass, so you need these specialized, ultra-hard abrasives to slowly grind through the material while keeping the bit cool with water.
No, standard drill bits are not suitable for glass drilling. Using the wrong type of drill bit, such as those meant for wood or masonry, will likely crack or shatter the glass. Always use a drill bit designed specifically for glass, like diamond or carbide-tipped bits, for best results.
To drill holes in glass without cracking it, use a diamond-tipped or carbide drill bit at a low speed (approx. 400 RPM) while constantly lubricating the area with water to prevent heat buildup. Apply very light pressure, letting the drill do the work, and avoid drilling near edges.
Yes, there are specific drill bits designed for glass. You cannot use standard wood or metal drill bits. The two main types you should look for are:
It's best to use water when drilling glass. It works as a lubricant and coolant but it's also needed to keep glass dust out of the air. Water can be trickled onto the cutting surface to wash the glass dust away. Some people prefer to surround the spot to be drilled with putty to hold water in place.
Glass can be drilled using a drill with a variable speed drive or a circular glass cutter, depending on the size of the hole and the thickness of the glass. To make the task easier, work slowly, cool the glass with water and use a carbide or diamond-tipped drill bit to prevent breakage. Read on for more top tips!
Carbide is significantly harder than cobalt. In industrial applications, carbide (often tungsten carbide) sits around 82 HRC on the Rockwell hardness scale, whereas cobalt steel reaches roughly 65 to 67 HRC.
Dremel offers specific diamond-impregnated core bits (like the Dremel 662 1/8" Bit and Dremel 663DR 1/4" Bit) to drill clean holes in glass. The 360-degree diamond grit allows you to rasp and widen holes, while the hollow core draws out dust.
One of the most fundamental rules in glass drilling involves the relationship between hole diameter and glass thickness. The hole diameter must be at least equal to the glass thickness, and preferably three times the thickness for optimal results. This rule becomes critical when glass undergoes thermal tempering.
You can drill in almost any glass there is, but some glass is a little more difficult just because it is harder to keep a steady stream of water applied to the surface friction point.
Does tempered glass break into sharp pieces? No, tempered glass breaks into small, relatively blunt fragments rather than long, sharp shards common to annealed glass.
Diamond Drill Bits: These are the best for drilling glass as they provide precision and minimize the risk of cracks.
Using a Dremel tool for drilling is a versatile and efficient way to create holes in various materials, including wood, soft metal, plastic, drywall, soft stones / shells, glass, tiles and masonry.
Yes, cobalt drill bits are absolutely worth the money—but only if you are regularly drilling through hard, abrasive metals like stainless steel, cast iron, or titanium. For drilling wood, plastic, or mild steel, standard high-speed steel (HSS) or titanium-coated bits are cheaper and perform perfectly well.
When it comes to raw strength, hardness, and heat resistance, Tungsten Carbide is the absolute strongest and hardest material used for drill bits. For maximum durability under heavy use and high impact without shattering, Cobalt is the preferred choice.
Carbide’s primary disadvantages include extreme brittleness, high upfront costs, and health hazards associated with certain compounds. Because it is hard but lacks toughness, tools are prone to chipping under shock or vibration.
Yes, there are specific drill bits designed for glass. You cannot use standard wood or metal drill bits. The two main types you should look for are:
Whether you're making home improvements or fitting a shopfront, toughened glass makes for a robust, energy-efficient and versatile option. But because of the way it's manufactured, it shatters when put under too much pressure. This makes it safe – but it also means you shouldn't drill it.
Temperature Difference (Thermal Shock)
Severity: The greater the temperature difference between the hot water and the glass, the greater the risk of the glass breaking. For example, pouring boiling water into a cold glass is riskier than pouring warm water.
Begin very slowly and gradually increase the drill speed up to a recommended speed of 5,000–30,000rpm for small holes. Please Note: The larger your drill bit is, the slower the speed should be as you begin. Increase only up to 700– 800rpm.
Regular glass, also known as annealed glass, is the most common type found in homes. It's relatively easy to drill through and is suitable for most DIY projects.