A walk-behind concrete grinder hires for roughly $100 to $180 a day and a larger propane or three-phase machine for $200 to $350, but the number that decides whether the job works is the vacuum. Grinding cured concrete dry without extraction fills the room with respirable silica and leaves a haze on every surface you were not working on.
Which grinder the job needs
A hand-held 5 or 7 inch angle grinder with a cup wheel suits edges, glue spots and a few square feet. A single-disc walk-behind of 10 to 12 inches covers a garage floor in an afternoon. Twin and triple-head planetary machines of 20 inches and up are for whole slabs, and they need the power supply and the doorway width to match.
The dust extractor is the job
OSHA pairs a hand-held grinder with a shroud and a dust collector rated at least 25 cubic feet per minute for each inch of wheel diameter, fitted with a filter of 99 percent efficiency or better. Walk-behind machines take a larger extractor still. Hire the vacuum with the grinder from the same counter so the hose, shroud and cyclone actually fit together.
Segments and pads are consumables
Diamond tooling is billed separately from the machine and is matched to the concrete, not to the grinder. Soft-bond segments cut hard cured slabs and hard bonds cut green or abrasive ones, which is the opposite of what most people guess. Tell the counter the age of the slab and what is on it, because paint, epoxy and mastic each want different tooling.
Rates and how long a floor takes
Day rates run near $100 to $180 for a single-disc walk-behind, $200 to $350 for a large planetary, plus the extractor at $60 to $120 and the tooling. A single pass on a 400 square foot garage is an afternoon. Coating removal is two or three passes, so book two days rather than discovering it at four in the afternoon.
Questions people ask about concrete grinder rental
Do I need water with a concrete grinder?
Not usually. Most rental grinders are run dry with a vacuum, because wet grinding makes a slurry that has to be squeegeed and disposed of. Wet cutting is more common on saws than on floor grinders.
Will a rented grinder remove epoxy or tile glue?
With the right tooling, yes. Sticky coatings load a standard diamond segment quickly, so ask for a PCD or a coating-removal head instead. It costs more per day and saves several hours of passing over the same floor.
How flat can a rented grinder get a slab?
A walk-behind will take off high spots and open the surface, which is what most flooring underlayment needs. Genuine flatness tolerances for polished concrete come from a heavy planetary machine and several tooling steps, which is a multi-day hire.