Quick Answer

Choose a diamond cup wheel for your angle grinder based on three things: the substrate, the task, and the grinder RPM. For general concrete grinding, a double-row or turbo diamond cup wheel in 115/125 mm is the default. For aggressive coating or laitance removal on a 180 mm grinder, use a segmented arrow or turbo cup wheel. For light bush-hammer texture, use a bush hammer plate. Match the bore to your grinder (M14 in Europe, 5/8-11 in North America), never exceed the max RPM marked on the wheel, and use a vacuum shroud for indoor work.

Segment Styles and What They Cut

Cup wheels come in several segment geometries, each with a job. Double-row wheels cut fast on general concrete and leave a moderate scratch pattern. Turbo (continuous turbo rim) wheels cut smooth and leave a fine finish — used on stone and for thin-coat prep. Arrow or segmented wheels are aggressive — used on laitance and heavy mortar. PCD cup wheels strip coatings. Bush hammer plates texture the surface for anti-slip.

Segment style	Aggressiveness	Finish	Best for
Double-row	Medium-high	Medium	General concrete, laitance, mortar
Turbo / continuous	Medium	Fine	Stone, marble, thin-coat prep
Arrow / segmented	High	Coarse	Heavy concrete, coatings, hard aggregate
PCD	Very high on resin	Variable	Epoxy, glue, mastic stripping
Bush hammer	Texture	Rough	Anti-slip, decorative texture

Diameter, Bore and RPM

Common cup wheel sizes are 100 mm (4"), 115/125 mm (4.5/5"), and 180 mm (7"). Match the wheel to your grinder's rated capacity — a 180 mm wheel on a small 115 mm grinder draws too much current and vibrates. The bore is M14 (most of the world) or 5/8-11 (North America). Check the max RPM on the wheel label: a 125 mm wheel is usually rated 12 200 RPM; a 180 mm wheel around 8 500 RPM. Running over the rated RPM can shatter the wheel.

Bond Selection

The bond is the metal matrix holding the diamonds. For soft concrete (C20-C25), use a hard bond — it holds the diamond longer. For hard, dense concrete (C40+), use a soft bond — it exposes fresh diamond. For very hard concrete or granite, use an extra-soft bond. Tell your supplier the concrete compressive strength and aggregate source when ordering; a wheel that glazes over (stops cutting) is almost always the wrong bond.

Using the Cup Wheel Correctly

Tilt the angle grinder at a 15-30° angle so only a 10-20 mm strip of the segment contacts the surface. Flat contact grabs and stalling the grinder. Move in slow, overlapping passes — do not dwell in one spot, which digs a trench. Let the tool do the work; pressing down only generates heat. For indoor work, mount a vacuum shroud and connect to a HEPA extractor via a dust collector adapter. Wear face shield, hearing protection, and gloves.

• Start the grinder off the floor, lower it gently, lift before stopping.
• Let the wheel run at full speed for 30 seconds before cutting.
• Use 125 mm wheels on 115/125 mm grinders; 180 mm wheels only on 180/230 mm tools.
• Replace the wheel when segments wear below 3 mm or are missing.

When to Use a Bush Hammer Instead

If the job is to create a non-slip texture on a ramp, stairs, or decorative concrete, a cup wheel will not do it — you need a bush hammer. The 5-125 mm bush hammer plate with three tungsten-carbide rollers creates an even, pitted texture at 1-2 mm depth. It is also the right tool for opening smooth trowelled concrete before recoating, where a cup wheel would polish instead of profile.

Frequently Asked Questions

Can I use a concrete cup wheel on granite or marble?

Use a turbo or continuous-rim wheel on stone; a double-row concrete wheel is too aggressive and will chip stone edges. For marble, choose a soft-bond turbo cup wheel designed for stone.

What bore do I need for my angle grinder?

European and Asian grinders are almost always M14. North American grinders are 5/8-11. Check the grinder flange before ordering — many cup wheels ship with a reducer ring, but the wrong bore will not bolt on.

Why is my new cup wheel not cutting?

Usually the bond is too hard for the concrete, or the wheel is glazed. Grind a cinder block or a brick for 30 seconds to expose fresh diamond. If it still does not cut, the bond is wrong for your substrate — order a softer bond.

How long does a 125 mm cup wheel last?

Typically 40-80 hours on medium concrete, depending on bond and aggregate. On hard flint aggregate, expect 20-30 hours. It is still far cheaper than abrasive discs.

Conclusion

Selecting a diamond cup wheel is a three-way match: segment style to the task, bond to the substrate, and diameter/bore/RPM to your grinder. Stock double-row wheels for general work, turbo for stone, PCD for coatings, and bush hammer plates for texture. Done right, one cup wheel lasts a crew for a job; done wrong, it glazes in a week.