Twisted Knot Cup Wire Brush M14x70mm - Angle Grinder Slag and Rust Removal

Twisted Knot Cup Wire Brush M14x70mm - Angle Grinder Slag and Rust Removal

The Twisted Knot Cup Wire Brush is a 70mm M14 wire brush designed for aggressive removal of slag, rust, paint, and surface residues on angle grinders. With 0.5mm twisted knot wire strands retained by a steel band and presented in a cup profile, it delivers concentrated surface contact across a defined working area, making it particularly effective for cleaning weld beads, removing slag from flame-cut and plasma-cut edges, and stripping heavy rust from steel sections where a bevel brush would not provide sufficient surface coverage. The cup profile presents the wire tips perpendicular to the work surface, which maximises the number of wire contacts per revolution and delivers a more aggressive cleaning action per pass than a bevel brush of equivalent diameter. Suitable for both mild steel and stainless steel, it covers the full range of weld cleaning and surface preparation tasks encountered in fabrication and structural steelwork.

Why Choose the Twisted Knot Cup Wire Brush

• 0.5mm twisted knot wire construction: the heavier 0.5mm wire gauge combined with twisted knot construction concentrates significant abrasive force at each wire tip, delivering aggressive slag, rust, and paint removal that lighter crimped wire brushes cannot match on heavily contaminated steel surfaces.

• Cup profile for maximum surface contact: the cup shape presents wire tips perpendicular to the work surface across the full 70mm diameter, maximising wire contacts per revolution and delivering consistent cleaning across weld beads and flat sections without the operator needing to adjust the working angle.

• Steel band wire retention: the retaining band around the wire bundle prevents individual strands from splaying outward at speed, maintaining the cup profile geometry under load and reducing the risk of wire ejection during aggressive grinding operations.

• Suitable for mild steel and stainless steel: the brush is specified for use on both mild and stainless steel surfaces, covering the full range of weld cleaning and surface preparation tasks in fabrication shops and on construction sites where both material types are worked.

• 70mm diameter for concentrated working: at 70mm, the brush is sized for concentrated cleaning on weld beads, flame-cut edges, and localised rust patches where a larger brush would be difficult to control or unable to access the working area cleanly.

• M14 direct thread fitment at 12,500rpm: mounts directly onto standard angle grinder spindles without an adaptor, rated for safe use on standard 115mm and 125mm angle grinders used across UK construction and fabrication sites.

What's Included

• One Twisted Knot Cup Wire Brush, 70mm diameter, M14 thread

 Specifications

 Compatibility

Who Is This For?

The Twisted Knot Cup Wire Brush is aimed at welders, fabricators, structural steelwork contractors, and general construction trades who carry out weld cleaning, slag removal, and surface preparation on mild steel and stainless steel. It suits the welder cleaning weld beads between passes and removing slag from completed welds before inspection, the fabricator stripping heavy rust and mill scale from steel sections before assembly, and the site operative removing paint and surface residues from steel components during refurbishment and maintenance work. This is a professional tool for aggressive surface preparation and weld cleaning, not for light cleaning or finishing work.

Typical Applications

• Removing slag and weld spatter from completed weld beads before inspection or further welding passes

• Cleaning flame-cut and plasma-cut steel edges before welding or mechanical joining

• Stripping heavy rust and mill scale from structural steel sections before painting, coating, or galvanising

• Removing old paint and deteriorated protective coatings from steel plate and structural sections

• Cleaning weld seams on stainless steel fabrications before surface finishing or inspection

• Removing surface residues, scale, and contamination from steel pipe and tube before joining or coating

• Preparing steel surfaces in confined areas where a larger diameter brush cannot access the working zone

How to Use

1. Confirm your angle grinder has an M14 threaded spindle and that the tool's maximum RPM does not exceed 12,500rpm by checking the tool nameplate before fitting.

2. Remove the current disc or attachment from the grinder. Thread the Twisted Knot Cup Wire Brush directly onto the M14 spindle by hand, tightening firmly without using a spanner on the brush body.

3. Ensure the correct guard is fitted to the angle grinder before operating. Do not operate a wire brush without the appropriate guard in place.

4. Run the brush at full operating speed for at least 15 seconds before making contact with the workpiece, observing from the side for any sign of wire breakage or imbalance.

5. Apply the brush to the workpiece with the cup face presented flat and perpendicular to the surface. Allow the twisted wire tips to make contact across the full working diameter without pressing hard into the material.

6. Use consistent, overlapping passes along the weld bead or across the surface for even material removal. For slag removal on weld beads, work along the bead direction to avoid wire snagging on the weld profile.

7. Inspect the brush periodically for broken or missing wire strands. Remove from the tool immediately if wire loss is evident or if the cup profile shows signs of deformation.

8. After use, remove the brush from the tool and store in a dry environment away from moisture to prevent wire corrosion.

Safety and Maintenance

Safety during use:

• Eye protection is mandatory: use a full face shield to EN 166, not safety goggles alone. Twisted knot cup brushes at 12,500rpm generate high-velocity wire fragments when individual strands break, which travel at sufficient speed to penetrate standard safety spectacles.

• Wear cut-resistant gloves to EN 388 for fitting, removal, and all operations where hand proximity to the brush or workpiece is unavoidable.

• Hearing protection to EN 352 is required. Angle grinders operating cup wire brushes consistently exceed 85dB(A).

• Respiratory protection: wire brushing slag, rust, and paint generates metallic fume and dust. Wear a minimum FFP2 mask to EN 149. If removing lead-based paint or other hazardous coatings, a full COSHH assessment is required before work begins.

• Never exceed 12,500rpm. Over-speeding a twisted knot cup brush dramatically increases the risk of wire strand ejection through the retaining band.

• Stand to the side of the brush rotation arc when starting the tool, not directly in line with the cup face.

• Do not use this brush on wood, plastic, or any surface where wire or metal contamination of the workpiece would cause a problem.

After use and storage:

• Inspect the brush after each use for broken wire strands, deformation of the cup profile, loosening of the retaining band, or reduction in wire length as strands wear back. Discard any brush showing significant wire loss, band loosening, or body deformation.

• Store in a dry environment. Moisture causes corrosion of the steel wire strands, weakening them and increasing the risk of strand ejection during subsequent use.

• Do not store wire brushes where they can contact other tools or hard objects that could deform the cup profile or damage the retaining band.

Frequently Asked Questions

Q: What is the difference between a cup wire brush and a bevel wire brush?

 A: A cup brush presents its wire tips perpendicular to the work surface across the full working diameter, maximising wire contacts per revolution for consistent cleaning on flat surfaces and weld beads. A bevel brush angles the wire tips outward for access into corner joints and angled sections. For weld cleaning and slag removal on flat and open surfaces, the cup profile is usually the more effective choice.

Q: What is the difference between a twisted knot cup brush and a crimped cup brush?

 A: Twisted knot brushes concentrate wire tension at the wire tip, delivering aggressive material removal suited to slag, heavy rust, and mill scale. Crimped brushes use corrugated wire strands that flex on contact, giving a more controlled cleaning action suited to loose paint and light rust on thinner materials. For slag removal and heavy rust stripping, twisted knot is the correct choice.

Q: Is this brush safe to use on stainless steel?

 A: Yes, this brush is specified as suitable for both mild steel and stainless steel. However, if the brush has previously been used on mild steel or carbon steel surfaces, ferrous contamination of the wire strands may occur, which can deposit iron particles onto stainless steel and initiate surface corrosion. For stainless steel work where contamination risk must be eliminated, dedicate a separate brush exclusively to stainless steel use.

Q: Will this brush fit my angle grinder?

 A: The Twisted Knot Cup Wire Brush has an M14 thread and fits directly onto any angle grinder with an M14 threaded spindle, the standard fitment on 115mm and 125mm angle grinders sold in the UK. Confirm your tool's maximum RPM does not exceed 12,500rpm before fitting by checking the tool nameplate.

Q: How do I know when the brush needs replacing?

 A: Replace the brush when you notice broken or missing wire strands, visible deformation or loosening of the steel retaining band, significant reduction in wire length as strands wear back, or any reduction in cleaning aggression that slows the work. A brush with a loose or deformed retaining band must be discarded immediately as band failure at speed presents a serious safety risk.

Q: What PPE is essential when using a twisted knot cup wire brush?

 A: A full face shield to EN 166 is the minimum for eye and face protection, not safety goggles alone. Cut-resistant gloves to EN 388, hearing protection to EN 352, and respiratory protection to at least FFP2 to EN 149 are also required for all wire brushing operations involving slag, rust, and paint removal.

Q: Can this brush remove slag from stainless steel welds without contaminating the surface?

A: The brush can remove slag from stainless steel welds effectively, but to avoid ferrous contamination, dedicate this brush exclusively to stainless steel use and do not use it on mild or carbon steel between stainless applications. For high-specification stainless fabrication where cross-contamination must be fully eliminated, use a dedicated stainless steel wire brush with stainless wire strands.

Q: Why should I order from CMT Group?

 A: CMT Group has supplied construction and industrial sites across the UK since 2010, with a fleet of over 100 FORS Silver accredited vehicles covering 90% of the UK mainland. Orders placed online by 7pm qualify for next working day delivery, and a VIP dedicated delivery service dispatched within 30 minutes is available UK-wide for urgent site requirements. CMT's EDGE procurement portal provides agreed contract pricing, spending controls, and live delivery tracking with What3Words integration for construction buyers managing multiple projects.