How to make precision cuts with a diamond saw

Hold the tile on both sides of the cut line and as you near the end of the cut, gently push the two pieces of tile together to prevent any breakage before the cut is complete.

To cut very hard materials like marble, granite or porcelain, it takes a diamond saw — an abrasive blade toughened by diamonds and cooled by water. And to get the best results when you make precision cuts with a diamond saw, it takes finesse. Diamond saw blades are abrasive rather than toothed like a wood-cutting blade. However, proper precautions should be taken and personal protective equipment (safety glasses, hearing protection) should be worn at all times.

Set the diamod saw up outside or in a garage if possible. If you need to cut in a finished room, cover the floor under the saw and the wall behind the saw with a tarp or plastic drop cloths to catch overspray and drips.

Basic cuts  with a diamond saw

Mark the tile – grease pencils work best with harder materials – and set in the sliding bed of the saw. Line up the cut mark with the blade without touching it, and turn on the saw. Wait for water to flow over the blade and slowly begin feeding the tile into the blade.

Hold the tile on both sides of the cut line and as you near the end of the cut, gently push the two pieces of tile together to prevent any breakage before the cut is complete. Slide the saw bed back toward you until the blade is clear of the tile.

Sliver cuts with a diamond saw

You sometimes need to remove a small sliver along one side of a tile. This can be tricky if you want to make precision cuts with a diamond saw as the blade wants to wander off the edge of the tile and it’s difficult to get a straight cut. To slice a narrow strip from the side of a tile, some saws come with a rip guide that will keep the sliver from bending or breaking away.

To rip slivers that are 1/8 inch or less (shaving away one edge in a straight line), use a scrap piece of tile as the guide instead of a rip fence. Trap the blade between the scrap and the tile you want to trim to keep the blade from wandering. Slicing that narrow with a rip fence can damage the fence.

To cut any angle through a single tile, you simply need to eyeball it. The trick to make precision cuts with a diamond saw is to sight down the cut line and line it up with the saw blade.

Diagonal cuts with a diamond saw

To cut any angle through a single tile, you simply need to eyeball it. The trick to make precision cuts with a diamond saw is to sight down the cut line and line it up with the saw blade. If your tile is shiny or hard to mark, put a strip of painter’s tape where you want to cut and mark the line on the tape. If your tile is too large to fit between the fence and the blade, tilt the tile up and rest it on top of the fence for the cuts.

Inside curve cuts with a diamond saw

Cut away as much excess material as possible with angle cuts and then make a series of cuts to the curved line, carefully breaking away the pieces with nippers or pliers. For the cleanest breaks, try to keep the pieces less than ½-inch wide and cut at a right angle to the curve, like bicycle spokes.

To clean up the curve, you can grind away any rough edges with the saw blade. Move the tile slowly across the blade, avoiding too much sideways pressure, which would damage the blade. Grip the tile firmly with both hands and nibble the excess tile away until you have a perfectly smooth curve.

–By Rob Fanjoy