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Best Angle Grinder Sizes for Bush Hammer Plates
The “right size” for a bush hammer plate on an angle grinder isn’t just a diameter choice. It’s a balance of coverage vs. control, RPM vs. torque, head mass vs. user fatigue, and the surface profile (CSP) you’re aiming to create. This field guide breaks down 115/125/150/180/230 mm setups with realistic speeds, power requirements, and use‑cases—so you can pick a configuration that is fast, safe, and produces a consistent texture. If you’re new to bush hammers, start with What Is a Bush Hammer and What Is It Used For? and How to Use a Bush Hammer on Concrete Floors.
Why size really matters: coverage, torque and CSP control
Plate diameter directly affects three things that you feel in the hands and see on the floor: coverage per pass (bigger plate, fewer lanes), required torque (larger rotating mass, higher load at impact), and texture consistency. Small plates (115–125 mm) are precise around steps and edges but cover slowly. Mid plates (150–180 mm) offer the best productivity‑to‑control ratio for most crews. Extra‑large (230 mm) plates can be fast on open concrete but demand a powerful, low‑speed grinder and excellent dust control to keep texture even. When the target is strict CSP 3–5 for coating adhesion, a stable mid‑size plate usually beats a lightweight small plate and is easier to keep uniform than a 230 mm head.
If your goal is flatness rather than texture (e.g., slab calibration), consider a milling wheel instead: What is a Diamond Milling Wheel and How It Works and our selection guide How do I choose the perfect diamond milling wheel for my project?
Fitment essentials: threads, shrouds, and speed control
Most angle‑grinder bush hammer plates mount on M14 spindles (EU/Asia) or 5/8‑11 (US). Verify the thread and flange height; poor seating causes run‑out and produces “washboard” texture. Use a variable‑speed grinder—typical no‑load speeds of 10,000–11,000 RPM are far too high for impact heads. For bush hammering, crews commonly run in the 1,500–4,000 RPM range depending on plate size, substrate, and head count. Always use a closed or semi‑closed dust shroud with HEPA extraction to control silica (OSHA 1926.1153 compliance) and to stabilize the tool on the surface.
For projects where texture is part of a coating‑removal workflow, map your approach with 5 Advanced Methods for Removing Coatings from Concrete and the long‑form strategy guide The Definitive Guide to Selecting the Best Coating Removal Method.
Size‑by‑size recommendations (power, RPM, use‑cases)
| Plate / Grinder Size | Typical Grinder Power | Recommended RPM Range* | Common Head Count | Best Use‑Cases | Pros / Watch‑outs |
|---|---|---|---|---|---|
| 115 mm (4.5") | 700–1,000 W | 2,000–4,000 | 3 heads (light) | Edges, stair nosings, façade details, small patches where precision is critical. | Ultra‑maneuverable; slow coverage. Easy to “dig in” if pressure is uneven. |
| 125 mm (5") | 900–1,200 W | 2,000–4,000 | 3–4 heads | Most hand work on stone and concrete; controlled CSP 2–4 and edge blending. | Balanced feel; still modest coverage on open floors. |
| 150 mm (6") | 1,400–1,700 W | 1,800–3,200 | 4 heads (30‑tooth typical) | General‑purpose floor work, stair treads, anti‑slip prep; CSP 3–5 consistently. | Great productivity‑to‑control ratio; needs variable speed and good extraction. |
| 180 mm (7") | 1,700–2,000 W | 1,600–2,800 | 4–5 heads | Open concrete, coatings tear‑down before grinding; deeper keying for overlays. | Fast lanes; heavier reaction force—keep passes steady to avoid banding. |
| 230 mm (9") | 2,200–2,600 W | 1,200–2,200 | 5–6 heads (heavy) | Large, open exterior slabs; roughening prior to shot‑blast/overlay on tight schedules. | Max coverage; only for trained users with strong dust control and low‑speed gearboxes. |
*Always check the plate manufacturer’s RPM limits. Excess speed can shatter rollers or glaze carbide pins.
Dialing speed with a simple formula
Peripheral speed is a helpful sense‑check. Use V (m/s) = π × D (m) × RPM / 60. As a rule of thumb for hand‑held bush hammering, most crews keep V in a conservative band to avoid violent impact and thermal spikes. Example: a 150 mm plate at 2,400 RPM → V ≈ 18.8 m/s. If you step up to 180 mm, keep the same V by dropping RPM slightly. A variable‑speed grinder with a steady trigger is worth its weight in gold for achieving uniform texture.
Texture outcomes (CSP) and how size affects uniformity
Angle‑grinder bush hammering typically yields CSP 2–5 depending on head geometry and feed. Smaller plates remove less per strike and can produce a finer “pebbled” look, ideal before thin films. Mid/large plates carry more inertia and bite deeper, making CSP 4–5 easier to achieve quickly. If you need a very uniform CSP for high‑build coatings, blend with a follow‑up grind as described in Advanced Methods for Removing Coatings. For decorative, slip‑resistant stone, see Types of Bush Hammers: Manual vs. Electric for tool choices beyond angle grinders.
Two field workflows (so you can pick with confidence)
Workflow A — Interior stair treads (granite) needing anti‑slip
Choose a 125–150 mm plate on a 1,400 W variable‑speed grinder with a compact shroud. Run 2,200–2,800 RPM, minimal pressure, overlapping passes. Aim for CSP 3–4, then lightly blend edges with diamonds. This keeps the nose crisp and the texture even without over‑eating corners.
Workflow B — Exterior concrete walkway with topcoat failure
Pick a 180 mm plate on a 1,800–2,000 W grinder. Set 1,600–2,200 RPM with a robust shroud and HEPA vac. Use steady lanes to remove the failing film and create CSP 4–5. Follow with dust verification and, if needed, a quick grind to standardize peaks. For full remediation logic, reference the coating removal guide.
Common mistakes and how to avoid them
The most expensive failures come from over‑speeding small plates, pressing too hard (“leaning in”), and running without a proper shroud. Excess RPM or pressure shocks the rollers and snaps carbide pins; lack of dust extraction loads the surface and forces you to push harder, compounding wear. Keep the tool flat, let the head roll, and make multiple light passes. For broader surface prep where uniformity matters more than raw bite, consider a diamond grinder sequence after bush hammering—or, if your true goal is thickness control, switch to a milling workflow: How to Maintain and Extend the Life of Your Diamond Milling Wheel.
Decision snapshot
- Mostly edges / small details: 115–125 mm for precision.
- General‑purpose, controlled CSP 3–5: 150 mm (sweet spot for most crews).
- Open floors / faster tear‑down: 180 mm (or 230 mm for trained teams with low‑speed gearboxes).
- Need flatness, not texture? Use milling wheels instead of bush hammers—see our articles linked above.
