Norton 66252839103 Knotted Cup Brush 4 Inch Carbon Steel

Product Description

The NORTON 66252839103 is a knotted carbon steel cup brush designed for aggressive surface preparation and weld cleaning on metal. The knotted wire configuration delivers concentrated, high-impact scrubbing action that removes mill scale, rust, slag, and coatings faster than crimped-wire alternatives. At 4 inches in diameter with a 0.02-inch wire diameter, this brush mounts via a standard 5/8-11 threaded arbor and is rated to 9,000 RPM. It is sold as a single-piece replacement unit and is typically installed by welders, pipefitters, ironworkers, and maintenance technicians who use angle grinders for prep and finishing work.

This cup brush is suited for use on mild steel, structural steel, and similar ferrous base metals in both shop and field environments. Common applications include weld joint prep, post-weld cleanup, removal of surface rust and oxidation, and paint or coating removal before inspection or recoating. The single-row knotted fill concentrates wire contact at the work surface for aggressive material removal. The 5/8-11 arbor thread is the standard size for most 4-inch to 5-inch angle grinders used in trades.

Key Features

• Knotted carbon steel wire for aggressive surface removal and weld cleanup
• 4-inch brush diameter suits standard trade-grade angle grinders
• 5/8-11 threaded arbor for direct mounting on compatible angle grinder spindles
• 9,000 RPM maximum speed rating for safe operation at grinder operating speeds
• 1.125-inch trim length provides consistent wire contact and extended service life
• Single-row fill design concentrates wire force for deeper surface penetration

Compatibility

Designed for use with angle grinders equipped with a 5/8-11 threaded spindle, which is the standard arbor on most 4-inch and 5-inch grinders used in welding, fabrication, and maintenance trades. Do not exceed the 9,000 RPM maximum speed rating of this brush.

Installation Notes

This brush is installed and removed by a qualified operator following standard angle grinder safety procedures. Always confirm the grinder spindle speed does not exceed 9,000 RPM before mounting. Wear appropriate PPE including face shield, safety glasses, and gloves during installation and operation. Inspect the brush for damaged or broken wires before each use and replace if wire fatigue or deformation is visible.