The Robert Charles Plain Shank Counterbore is built for professionals who demand durable, precise counterboring in metalworking. Crafted from M35-HSS-E with 5% cobalt, it delivers reliable performance in precision engineering, automotive, and general workshop settings.

• Material and grade: M35-HSS-E with 5% cobalt for excellent heat resistance, wear life, and sustained cutting performance.
• Shank type: Plain shank design for easy fitment in standard tool holders, enabling stable, reliable machining.
• Size and geometry: 5/8 cap screw size with a 0.641 pilot size for accurate alignment and clean, consistent counterbores.
• Counterbore precision: Optimized flute geometry and sharp cutting edges to produce clean, flat-bottom counterbores with minimal burrs.
• Durability and reliability: Designed for repeated use in demanding shops, maintaining accuracy and cutting performance over long runs.
• Ideal applications: Perfect for precision engineering, automotive assembly, and general workshop tasks requiring durable, repeatable counterboring results.

This counterbore delivers precise depth control and stable operation, helping you reduce rework and improve overall machining efficiency. The cobalt-enhanced HSS edge stays sharp longer under demanding conditions, while the plain shank ensures quick tool changes and seamless compatibility with standard tool holders. Whether you’re prepping fastener holes in steel components or preparing fixtures for tight tolerances, this counterbore provides consistent, reliable results match after match.