Precision Twist Drill 5997779 Cobalt Jobber Drill Bit

Product Description

The PRECISION TWIST DRILL 5997779 is a cobalt jobber-length drill bit sized to wire gauge 61 (0.0390 inches decimal), designed for general-purpose drilling in steel and other demanding workpiece materials. Built to a 135-degree split point geometry with web thinning, it starts on center without a pilot hole and drives through material with less thrust than a conventional 118-degree point. The straw oxide finish provides light lubricity and corrosion resistance. At 1.625 inches overall length with an 11/16-inch flute, this is a compact, right-hand-cut bit suited for close-quarter work and precision hole placement in production and maintenance applications.

This bit is rated for drilling steel (material codes P, M, K, N, S), making it appropriate for use by machinists, maintenance technicians, and metal fabricators working on ferrous and non-ferrous stock. The regular spiral flute and tapered web configuration promote chip evacuation in through-hole drilling operations. It meets ANSI standards and carries a NAS 907 specification designation, making it suitable for aerospace and heavy-duty industrial applications where dimensional and material compliance are required. Coolant-through capability is not supported on this design.

Key Features

• Cobalt high-speed steel construction for heat and wear resistance in steel drilling
• 135-degree split point with web thinning for self-centering starts and reduced thrust
• Wire size 61 diameter (0.0390 inches) for precision small-diameter hole applications
• Straw oxide finish for light lubricity and surface protection
• Right-hand cut, regular spiral flute for efficient chip removal
• Meets ANSI standards and NAS 907 specification

Compatibility

Part of the R10CO-R15CO-R18CO series. Compatible with standard straight-shank drill chucks accepting a 0.0390-inch shank diameter. Rated for drilling steel and compatible workpiece material codes P, M, K, N, and S per series specification.

Installation Notes

Install in a drill press, CNC machine, or hand drill with a chuck rated for the 0.0390-inch straight shank diameter; verify chuck jaw range before use. Power down all equipment fully before changing bits. For steel applications, use appropriate cutting fluid to extend tool life and maintain hole quality. Secure workpieces with proper fixturing to prevent movement during drilling.