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Diamond Grains do the Cutting

The cutting surfaces of these grinders are diamond grains held by “segments,” the raised metal parts of the wheel. An aggressive wheel, which can take down 1/4 in. of concrete or more, grinds away material faster but leaves a rougher surface. A less aggressive wheel removes smaller amounts of concrete and leaves a smoother surface.

Here’s the rule of thumb for choosing a wheel: The more surface area it has, the less aggressive the wheel. Choose an aggressive one to remove high, long ridges or large, rough areas of concrete, and a less aggressive one for tasks like cleaning up tile thin-set residue from a wall or prepping for an epoxy coating.

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Wear Safety Gear!

Plan to deck yourself out in safety gear: hearing protection, safety glasses and a respirator. The high-speed machines are loud and can send concrete rubble flying from the grinding wheel. Grinding concrete also releases fine silica dust, which can cause health problems. Always wear a NIOSH-certified N95-rated respirator. Check the seal with this easy test: If you can exhale and inhale sharply without air escaping, you’re good to grind. If you have facial hair, even a bit of stubble will ruin the seal. Go ahead and shave—it will grow back!

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Keep the Machine in Motion

While you’re grinding, keep the cutter head moving, especially with a large floor grinder. Pivot the machine on its wheels, moving the cutter head in an arcing motion. If the cutting surface is riding on only one edge, work the machine in small circles to flatten out the surface.

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