Precision Twist Drill 5999084 Cobalt Jobber Drill Bit Y

Product Description

The PRECISION TWIST DRILL 5999084 is a Letter Y cobalt jobber-length drill bit engineered for heavy-duty drilling applications in steel and other demanding workpiece materials. Built from cobalt high speed steel with a straw oxide finish, this bit delivers extended tool life and heat resistance compared to standard HSS tooling. The 135-degree split point reduces walking on entry and requires less thrust force, making it well suited for production drilling environments. At 5.25 inches overall length with a 3.875-inch flute, it follows the standard jobber length-to-diameter ratio of 10xD. The straight cylindrical shank is compatible with standard drill chucks and collet holders without modification.

This drill bit is designed for right-hand cutting in a standard drill press, CNC machining center, or hand-held electric drill. Primary workpiece materials include steel, cast iron, nonferrous metals, and high-temperature alloys, consistent with workpiece material codes P, M, K, N, and S. It is built to NAS 907 and ANSI standards, making it appropriate for aerospace, metalworking, and industrial maintenance applications where dimensional and performance tolerances matter. The web-thinned, tapered web construction reduces cutting resistance during entry and chip evacuation through the regular spiral flutes.

Key Features

• Letter Y size (0.4040 inches decimal equivalent) for precise hole sizing
• 135-degree standard split point reduces thrust and minimizes bit walk on entry
• Cobalt HSS construction with straw oxide finish for improved heat and wear resistance
• Web-thinned, tapered web reduces cutting resistance and improves chip flow
• Right-hand, regular spiral flute with 3.875-inch flute length for deep drilling clearance
• Meets NAS 907 and ANSI standards — suitable for aerospace and precision manufacturing

Compatibility

Part of the R10CO-R15CO-R18CO series. Compatible with standard straight-shank drill chucks and collet systems accepting a 0.4040-inch shank diameter. Suitable for use in drill presses, CNC machining centers, and electric hand drills configured for right-hand cutting.

Installation Notes

Installation and use should be performed by machinists, toolroom technicians, or qualified maintenance professionals familiar with metal-cutting operations. Secure the shank fully in the chuck or collet before operation and verify runout is within acceptable limits for the application. This bit does not support coolant-through delivery; apply cutting fluid externally when drilling steel or high-temperature alloys to manage heat buildup. Follow machine manufacturer guidelines and applicable ANSI safety standards for rotating tool operation.