Quick Answer

Big grinders miss 5-10 cm along walls and columns. You finish those edges with a hand-held angle grinder fitted with a diamond cup wheel (4-5 inch), a dust shroud, and a P3 respirator. For tight corners, use a 3-inch cup wheel or a die grinder with a diamond burr.

The Edge Problem

A 700 mm push grinder reaches to within ~8 cm of a wall. That strip never gets ground, and if you polish the open floor without finishing the edges, the contrast is obvious.

Tools You Need

Area	Tool	Use
Wall edge	5-inch diamond cup wheel + shroud	Coarse to fine
Columns	4-inch cup wheel	Smaller reach
Tight corners	3-inch cup wheel or diamond burr	Reach into angles
Expansion joints	Hand grinder with flap disc	Clean out joint filler

Match the grit to the main grinding pass. If the big grinder is on 120 grit, the edge tool should also be 120.

Technique

• Keep the cup wheel flat. Tilting it creates a gouge.
• Overlap the big grinder's last pass by 2-3 cm so the transition is invisible.
• Use a vacuum shroud. Edge work without extraction is the dustiest part of the job.
• For corners, finish by hand with a resin hand pad.

See the full tooling range in our concrete grinding discs category.

Frequently Asked Questions

Q: Can I use a PCD cup wheel on edges?

Yes, for coating removal. Switch to metal bond once the wall edge is bare concrete.

Q: How do I avoid swirl marks on edges?

Keep the wheel flat and move smoothly. Small circular motions leave swirls.

Q: Do I need a special grinder?

A standard 5-inch angle grinder with a vacuum shroud works. A variable-speed model is easier to control.

Conclusion

Edges make the floor. Carry a cup wheel set in every grit and a 3-inch corner wheel. contact JOY TECH for edge tooling compatible with your holder system. diamond cup wheels and core drills