Granite is an igneous rock (solidified from a fluid state) with a crystalline textured. It is usually comprised of quartz and microcline. Because of its hard surface, special tools are required for cutting into, drilling through or shaping granite. To cut granite in any way, you will need a masonry diamond blade. Masonry diamond blades range from 4 inches to 24 inches. Diamond blades are used for wet and dry cuts.
As long as a diamond blade is used, you can use a table, tile or handheld saw to cut granite. Depending on the job, use these saws wet or dry. Use a table or tile saw to cut through small, flat pieces of granite such as granite tiles. Use a handheld saw for larger pieces such as counter slabs and sculptures.
You can rent both the saw and the blade from hardware stores that have a tool rental service.
Bit vs. Blade
To slice through granite you will use a diamond blade. To drill through granite you will need a diamond bit. Use a diamond bit to drive holes through granite countertops for installation applications for faucets.
Wet cutting vs. Dry Cutting
Using a wet saw with a wet diamond blade reduces the risk of chipping or breaking the granite. Wet cutting also reduces heat and makes cutting through granite easier. You typically use wet cutting blades for walk behind saws such as a tile saw. These saws have a tub under the blade where water is stored so it can be continuously sprade onto the blade. When using this saw, water will seep out onto the ground and spray a mist around the saw, so it should be used outside. Use a wet blade for deep cuts that go through granite.
Dry cutting reduces the mess of wet saws but produces more dust. If you are cutting granite indoors, a dry cut is your best option because a wet saw produces large amounts of water. Dry cutting blades have segmented welds which resist heat and do not require water for cooling. Use a dry cutting blade when using a handheld saw with low horsepower to contour or shape granite.
Types of Blades
Standard Masonry Blades – For cutting straight though granite slabs and tiles. Laser Welded Segmented Blades – For general purpose cutting.
Contour Blades – For curved cutting applications.
Rod Blades – For cutting grooves into granite. Used for sink applications.
Diamond Drill Bits – For milling through granite.
Profile wheels – For shaping and polishing the edges of granite.
Grinding Cup Wheels – For smooth shaping and finishing granite.
Most diamond blades and diamond bits are manufactured for wet or dry applications or both.
Saw Manufaturers Institute (SMI) has developed a common blade application code for use on diamond blades of 12" diameter or larger. Use of the code by blade manufacturers and distributors is strictly voluntary.
According to the Association of Equipment Manufacturers, you may use many dry blades as wet blades. However, never use a wet blade as a dry blade.
You may download a free version of the Diamond Blades Safety Manual from the Association of Equipment Manufacturers. This pamphlet covers general safety information such as blade wear and condition analysis, mounting, and machine safety.