Cutting and Drilling Ceramic and Stone Tiles
November 13, 2007
Few tile installations can be completed without some cutting or drilling. For an installer working with ceramic and stone tiles, several hand and power tools are needed for the most efficient cutting. I divide cutting chores into two categories: cut edges that show, and cut edges that are obscured or hidden from view. This distinction is an important one since cutting a tile can destroy the smooth lines of the factory edge and makes the cut edge more obvious.
For this reason, I generally use a wet-cutting diamond blade for show cuts, and use other cutting tools and methods for hidden cuts. After cutting on a wet saw, I blunt the sharp-cut edge with a hand rubbing stone. If the glaze contrasts with the body of the tile, I barely round over the cut edge with the stone. If the glaze matches or complements the bisque, or if the tile is a through-color unglazed porcelain tile, I use a rubbing stone or belt sander to match the contour of the factory edge as closely as possible for the cleanest appearance. For the professional installer, a combination of hand and power tools is required for every installation. I try to select the most appropriate tool to suit the volume of cutting and drilling required.
When only a small amount of material has to be removed from around the edge of a tile, biters can be used to nibble away the unwanted portions. Biters leave a ragged cut, but with enough practice, they can be surprisingly versatile. If the edge shows, it can be smoothed with a rubbing stone. An alternative to making irregular cuts with hand-held biters is cutting them with either dry or wet cutting diamond blades. Vacuum hoods are available to help contain the copious amounts of dust generated by the typical 4” angle grinder used by many installers, but I use wet-cutting methods whenever possible, and prefer longer tool life, a finer finish, and dealing with wet cutting sludge that is relatively easy to contain, over a less glossy finish, reduced tool life, and the notorious clouds of ultra-fine particles of dust generated by dry-cutting and polishing equipment.
Wet SawA wet saw is indispensable for L-cuts, show-cuts, and for straight-cutting cast, agglomerated, and stone tiles. A wet saw can be fitted with soft, medium, and hard blades, porcelain blades, profiling wheels (for cutting bullnose edges), and in a pinch, most can even be fitted with dry-cutting diamond blades (and run wet or dry). When buying a saw, I always check the angle between a saw’s blade and its fixed, front fence with a square to ensure the saw will cut at 90-degrees - no more and no less. I also check to see if the blade is perpendicular to the sliding table so the cut shoulder is 90-degrees as well, and examine the machine closely so that all its functions perform as expected. This also applies to the adjustable cutting fence.
Once satisfied with the accuracy of a saw, I cut a shallow locator notch in the sliding table’s blade-relief trench. This notch helps me align tiles for diagonal cutting. To make repeat cuts, since not all tiles in a lot will be exactly the same size, set up the fence so that the desired off-cut sits between the fence and the saw blade. For cutting hard or soft tiles, slowly introduce the tile to the blade, increase the cutting speed when the kerf is about 1” long, and decrease the cutting rate as the blade approaches the last inch of cutting. Slowing the feed rate at the beginning and end of the cutting cycle reduces breaks and waste.
Since most wet saws recycle - without filtering - water used to cool the blade, at some point the coolant water becomes loaded with abrasive cutting sludge that clings to the tiles being cut, and which can form a bond-breaking layer on the backs of cut tiles. Unless clean water, only, is used for cutting, all cut tiles should be rinsed with clean water and dried of all excess moisture before they are installed in a bed of adhesive.
Drilling HolesHole saws, sometimes called core bits, are available in carbide or diamond, and in either wet- or dry-cutting formats. I resist buying carbide core bits because they do not seem to cut with much accuracy, or have a very long life. Instead, I use nothing but wet-cutting diamond bits, and use the catch basin of a typical wet saw as part of my drilling setup. I place a square of 3/4” plywood at the bottom of the basin to protect it from damage, and use a jig also made of scrap plywood, to guide the bits. As you may already have discovered, the carbide pilot bits used in most core bits, are ineffective when used with porcelain tiles.
With the jig positioned with one hand, I use the other to drill through the glaze or the top surface of the tile. After the tile has been grooved, I remove the jig because it can restrict the flow of cooling water to the bit. When finishing the hole, I hold the drill securely and let the core bit feed itself through the rest of the tile. Whenever possible, large holes should be drilled prior to installation. Whether done before or after, large hole or small, water should always be used to cut ceramic or stone.
Dry-CuttingWhen wet-cutting of tile is impractical or not desired, I use one of several dry-cutting saws: a small circular-type saw fitted with a 4”, continuous-rim, dry-cutting diamond blade, a right angle grinder fitted with an identical blade, and a wet saw with its normal blade replaced by a dry-cutting blade sized for the saw. I generally only resort to dry methods when I am working with a permeable stone whose body would be discolored by wet-cutting. In addition to Absolute, dry dust collection is always a problem requiring, at times, very detailed masking-off of on-site and shop peripheral areas, dust-collection and filtration units, and point-of-origin, tool-head collection. Dry-cutting, on-site at an occupied building, must be done very carefully to prevent cutting or polishing dust from getting onto other finished surfaces, and into unwanted areas.
Edge PolishingFor on-site edge profiling, polishing, and production-cutting tasks, I use a through-spindle-coolant angle grinder made specifically for wet cutting; at the shop, I use - always with water - either electric or air-powered grinding and polishing tools. To help with edge polishing and edge softening, I use a bench top sander fitted with 4" x 36" x 120-grit belts, and find it indispensable when softening the edges of porcelain show cuts. For just a few edges, a tile rubbing stone is the most efficient way to do this work, but when hundreds of cut edges need to be smoothed, a bench top belt sander can get the job done fast, with a minimum of repetitious hand labor with a rubbing stone.
TCNA Handbook, ANSI Handbook, www.tileusa.com
Photos courtesy of Michelle Griffoul, www.michellegriffoul.com
Circular saw, dry-cutting blades, core bit, wet angle grinder, and diamond polishing pads manufactured by MK, www.mkdiamond.com
Angle grinder and 1/2" drill manufactured by Makita, www.makita.com