Precision Twist Drill 5998164 Cobalt Jobber Drill 25/64 in

Product Description

The PRECISION TWIST DRILL 5998164 is a cobalt jobber-length drill bit designed for heavy-duty drilling in ferrous and non-ferrous metals. Ground to a 135-degree split point, it self-centers on contact and reduces the walking common with standard 118-degree geometry. The straw oxide finish provides lubricity and mild heat resistance during high-speed operation. At 5.125 inches overall length with a 3.75-inch flute, this bit suits standard jobber-depth applications in drill presses, CNC machining centers, and hand-held drill motors. A web-thinned, tapered web design reduces thrust load and chip packing in deeper cuts. Licensed machinists, maintenance technicians, and metalworking pros reach for this geometry when drilling structural steel, alloy steel, and similar materials.

This bit is sized at 25/64 inches (0.3906 inches decimal) with a matching straight cylindrical shank of the same diameter. It is built to ANSI standards and carries a NAS 907 specification designation, making it appropriate for aerospace and precision industrial environments. Primary workpiece material codes P, M, K, N, and S indicate suitability for steel, stainless, cast iron, non-ferrous metals, and high-temperature alloys. Series R10CO-R15CO-R18CO covers 10xD flute-to-diameter ratios in this cobalt line.

Key Features

• Cobalt high-speed steel construction for elevated heat resistance in hard-metal drilling
• 135-degree split point with web thinning for self-centering and reduced thrust
• Straw oxide coating adds lubricity and surface protection
• Regular spiral, 2-flute design promotes efficient chip evacuation
• Straight cylindrical shank fits standard 3-jaw chucks without adapters
• Meets ANSI standards and NAS 907 specification for precision and aerospace applications

Compatibility

Designed for use in standard drill chucks accepting a 25/64-inch straight shank. Rated for drilling steel, stainless steel, cast iron, non-ferrous metals, and high-temperature alloys per primary workpiece material codes P, M, K, N, and S. Part of the PRECISION TWIST DRILL Series R10CO-R15CO-R18CO cobalt jobber line.

Installation Notes

This bit is installed and operated by machinists, maintenance technicians, and metalworking professionals. Secure the shank fully in the chuck and verify concentricity before high-speed operation. Use cutting fluid appropriate for the workpiece material to extend tool life and prevent work-hardening in stainless and alloy steels. Do not exceed the rated maximum drilling depth of 3.75 inches in a single pass without chip-clearing peck cycles.