The Robert Charles Plain Shank Counterbore is a high-performance cutting tool designed for precision counterboring in metalworking. Built from M35 HSS-E with 5% cobalt, it delivers exceptional heat resistance, wear life, and cutting performance for engineers, machinists, and automotive professionals who demand dependable results.

• Material: M35 HSS‑E with 5% cobalt, delivering enhanced heat resistance and wear resistance for longer tool life in demanding metals.
• Shank Type: Plain shank for straightforward fitment in standard tool holders, ensuring stable, repeatable machining.
• Pilot Size: 0.312 inch pilot to guide the bore with precision and maintain alignment throughout the cut.
• Cap Screw Size: 5/16 cap screw compatibility for secure installation in appropriate tooling setups.
• Counterbore Geometry: Optimized cutting edges and flute geometry for clean, square counterbores and consistent bottom finishes.
• Applications: Suited to precision engineering, automotive manufacturing, and general workshop use where durability and reliability matter.

With its cobalt-enhanced alloy and a plain shank designed for standard holders, this counterbore supports repeatable depth control and smooth chip flow, reducing heat buildup and wear during extended operation. The 0.312 inch pilot fosters accurate bore guidance, while the 5/16 cap screw sizing ensures quick, secure setup. For practitioners performing high-tolerance assemblies or precision pocket counters, this tool delivers dependable performance, helping streamline workflows and reduce rework in metal fabrication and repair environments.