Quick Answer: A 7-inch angle grinder with a diamond cup wheel is the best tool for fast concrete grinding on floors, walls, and edges. Keep the wheel flat against the surface, work in overlapping passes, and use a dust shroud with a vacuum so the work stays clean and the segments cut at full power.

Why 7 Inches Is the Sweet Spot

A 7-inch grinder balances speed and control: it removes material much faster than a 4.5-inch machine, yet stays light enough for walls and edges where a floor grinder cannot go. It is the standard tool for smoothing slabs, leveling patches, removing coatings, and prepping concrete for polishing.

For deep grinding or large open floors, a walk-behind machine is faster; for everything else, the 7-inch grinder wins on versatility.

Choosing the Cup Wheel

Match the wheel to the job:

• Coarse single-row or double-row cup wheel: fast stock removal and coating stripping.
• Flat-segmented trapezoid disc: smooth, even surface work with less vibration.
• PCD tooling: coatings and glue removal without loading.

For general surface prep, a 180mm cup wheel with arrow segments removes material quickly and runs cooler than aggressive designs.

Grinding Technique

1. Run the grinder at full speed before touching the surface.
2. Lower the wheel flat, then sweep in overlapping passes of about half the wheel width.
3. Let the wheel's weight do the cutting; press only lightly with your arms.
4. Work in a pattern, not random spots, so the surface stays even.
5. Stop and check the surface with a straightedge on high spots.

Do not tilt the grinder: a tipped cup wheel digs a groove and makes the job worse. Flat, even, overlapping passes are the whole secret.

Dust and Safety

Concrete dust is silica dust, so run a shroud and HEPA vacuum with every pass, wear a respirator and goggles, and take breaks on long jobs. The grinder throws sparks when it hits metal, so clear the area of flammables before you start.

FAQ

Can a 7-inch angle grinder grind a whole floor?

Yes, on small floors and patches. For large areas, a walk-behind grinder is faster, but the 7-inch tool handles edges, corners, and tight spaces.

What cup wheel is best for leveling concrete?

A flat cup wheel or trapezoid disc with a medium grit. Flat designs remove high spots without gouging.

Do I need a dust shroud when dry grinding?

Yes. A shroud with a vacuum keeps silica out of the air and the segments clear of slurry, so the wheel cuts faster and lasts longer.

Conclusion

Flat wheel, overlapping passes, and serious dust control: that is the 7-inch grinder routine. With the right trapezoid grinding disc and cup wheel, it handles everything from slab prep to coating removal in one tool.