Product Specification
4" X 5/8"-11 KNOTTED CUP BRUSH - CARBON STEEL
When you need to strip a larger steel surface fast, the 4" x 5/8"-11 Knotted Cup Brush - Carbon Steel gives you a wider, more aggressive cleaning footprint for heavy rust, mill scale, weld residue, paint, coatings, oxidation, and stubborn buildup. Built with 0.020" carbon steel wire, this is the step up for jobs where smaller cup brushes simply do not cover enough ground.
The knotted wire construction bundles the wire into stiff, tightly twisted sections that stay firm under load and deliver concentrated cleaning force at the wire tips. Combined with the larger 4" cup profile, that creates a broad, stable working area for cleaning steel plate, structural components, weldments, fabricated assemblies, and other demanding metal surfaces.
A 4" diameter, 5/8"-11 threaded arbor, and 9,000 RPM maximum rating make this brush a serious choice for compatible professional angle grinders used in fabrication, welding, structural work, maintenance, and repair. When the goal is aggressive surface cleaning with more coverage per pass, this larger knotted cup is built to get the job done.
Product Specifications
| Specification |
Details |
| Diameter |
4" |
| Wire Material |
Carbon Steel |
| Wire Diameter |
0.020" |
| Wire Style |
Knotted |
| Brush Type |
Cup Brush |
| Arbor |
5/8"-11 Threaded |
| Maximum RPM |
9,000 |
Features
-
Aggressive knotted-wire construction for medium- to heavy-duty surface cleaning
-
0.020" carbon steel wire attacks rust, scale, weld residue, paint, and stubborn buildup
- Large 4" cup profile provides increased surface coverage
- Broad, stable contact area for efficient cleaning of plate, structural steel, and fabricated components
- Stiffer and more aggressive than flexible crimped-wire cup brushes
-
5/8"-11 threaded arbor for quick spin-on installation
- 9,000 RPM maximum rating
- Excellent for welding, fabrication, structural work, maintenance, repair, and general steel preparation
- Strong choice when productivity across larger surfaces matters
Applications & Performance
The 4" knotted cup brush is built for aggressive broad-surface cleaning. Its larger cup profile places more wire against the workpiece than smaller cup brushes, helping crews cover bigger surfaces with fewer passes.
Common applications include:
- Heavy rust and corrosion removal
- Mill scale removal
- Weld cleanup
- Removing weld residue and spatter
- Paint and coating removal
- Oxidation removal
- Cleaning steel plate
- Structural-steel preparation
- Cleaning fabricated assemblies
- Surface preparation before welding
- Preparing metal before coating or repair
- General industrial maintenance
The larger 4" working footprint is especially useful on plate, structural components, tanks, frames, weldments, and other jobs where faster broad-area cleaning is more important than tight-access maneuverability.
Use controlled pressure and let the wire tips do the work rather than forcing the brush into the surface.
Materials
Recommended for cleaning and surface preparation on compatible ferrous materials, including:
- Carbon steel
- Mild steel
- Structural steel
- Cast iron
- Wrought iron
- Other compatible ferrous metal surfaces
Keep carbon steel brushes dedicated to ferrous work when cross-contamination matters. For stainless-steel applications where iron contamination must be minimized, use a dedicated stainless steel wire brush.
Machine Compatibility
Use this 4" cup brush on a compatible angle grinder with a 5/8"-11 spindle, adequate brush capacity and a maximum speed no greater than 9,000 RPM. Match the actual hub seating and allow room for wire flare.
Compatible examples include:
-
Makita® GA7011C — 7" angle grinder; 6,000 RPM.
-
Makita® GA7021 — 7" angle grinder; 6,600 RPM.
Other machines may be compatible. Use the manufacturer-specified wire-brushing setup and guard, with secure hub engagement and adequate operating clearance. Other grinders meeting these requirements may also be suitable.
Safety Tips
- Never exceed the brush's 9,000 RPM maximum speed.
- The brush's rated RPM must meet or exceed the maximum operating speed of the power tool.
- Confirm the grinder is designed to safely accommodate a 4" cup brush and its operating wire flare.
- Inspect the brush before every use and replace it if damaged, excessively worn, loose, or distorted.
- Confirm the 5/8"-11 threaded arbor is fully seated and secure before operation.
- Use the appropriate grinder guard and maintain adequate clearance around the rotating brush.
- Wear proper PPE, including eye and face protection, hearing protection, gloves, appropriate clothing, and respiratory protection when required.
- Keep bystanders away from the work area and direction of rotation.
- Use controlled pressure. Excessive force bends the wire and can accelerate wire fatigue.
- Allow the grinder to reach operating speed before contacting the workpiece.
- Follow all operating and safety instructions for both the power tool and wire brush.
