I recently needed to remove some ceramic tile that had been placed on concrete in a living room and adhered with thinset. After using my small electric demolition hammer drill to chip away the tile, there was still plenty of thinset residue firmly attached to the slab.

My 4-in. angle grinder with a cup-grinder attachment would make short work of the thinset, but the dust would be overwhelming to the operator (not to mention to the homeowners, who would rue the day they let me in the door).

After looking closely at the grinder, I discovered that if I removed the guard/handle, I could replace it with a piece of 1/4-in.-thick Plexiglas with three well-placed holes—a large one for the shaft and two small ones to affix the plastic to the body of the grinder. I made the Plexiglas a generous 2 in. larger than the diameter of the cup grinder. Next, I made an oak frame of 1x stock so that the business surface of the cup grinder extended past the frame. To the outside of the frame, I attached nylon-bristle-type weatherstripping, as shown in the drawing (left). The bristles are positioned so that they have to be compressed a bit before the grinder engages the worksurface. To keep the bristles in position, I cut a shallow rabbet around the perimeter of the oak frame for the aluminum edge of the weatherstripping to bear against, and I attached it to the frame with screws.

Finally, I drilled a 13/8-in. hole in the oak frame for a vacuum nozzle. With the hose attached, I taped it to the grinder’s body to keep it in place. This contraption worked like a champ. Prepping the floor for new tile, I was able to grind down to a smooth concrete surface with little dust escaping. I also used this tool to remove paint from a patio slab before tile was set. The dust that escapes is minimal provided the grinder is kept level, but the operator should still use a dust mask. The vacuum I used is designed to pick up drywall dust. It has a paper-bag liner that collects fine dust.

—David Guth, Oak Park, CA

Edited and Illustrated by Charles Miller

From Fine Homebuilding #206