Norton 66252839090 Knotted Cup Brush 4 in Carbon Steel

Product Description

The NORTON 66252839090 is a knotted carbon steel cup brush designed for aggressive weld cleaning, rust removal, and surface preparation on metal. The 4-inch diameter brush features a single-row knotted wire configuration using 0.23-inch diameter carbon steel fill, delivering the bite and durability needed for heavy mill scale, spatter, and corrosion removal. It mounts via a standard 5/8-11 threaded arbor, making it compatible with most right-angle grinders used in fabrication and maintenance environments. Rated at 9,000 maximum RPM, the brush is suited for sustained grinding work on structural steel and weldments. Licensed trade professionals and industrial maintenance crews are the primary users.

This cup brush is used in welding shops, structural steel fabrication, pipeline maintenance, and general metalworking applications. It is appropriate for both shop and field use wherever a right-angle grinder is the primary tool. The single-row knotted design concentrates wire contact for fast, consistent material removal on flat and slightly contoured steel surfaces. A 1.25-inch trim length supports stable wire presentation during use.

Key Features

• 4-inch brush diameter for broad surface coverage on cup brush applications
• Knotted carbon steel wire at 0.23 inches diameter for aggressive cutting action
• 5/8-11 threaded arbor hole fits standard right-angle grinder spindles
• 9,000 maximum RPM rating for compatibility with common grinder speeds
• Single-row configuration for concentrated wire contact and fast material removal
• 1.25-inch trim length for consistent brush geometry over the working life

Compatibility

Designed for use with right-angle grinders equipped with a 5/8-11 threaded spindle, which is the standard arbor size for 4-inch and 4.5-inch angle grinders in industrial and trade settings.

Installation Notes

Installation is performed by qualified personnel familiar with abrasive tool safety. Always power down and disconnect the grinder from its power source before mounting or removing the brush. Thread the brush fully onto the 5/8-11 spindle and verify it is seated securely before operation. Always confirm the grinder free-speed RPM does not exceed the 9,000 RPM rating of the brush, and use appropriate PPE including eye and face protection per ANSI B11 and OSHA abrasive wheel standards.