Precision Twist Drill 5998168 Cobalt Jobber Drill 27/64 in

Product Description

The PRECISION TWIST DRILL 5998168 is a cobalt high-speed steel jobber-length drill bit designed for drilling into steel and other demanding workpiece materials. It features a 135-degree split point and a web-thinned, tapered web configuration that reduces walking and lowers thrust requirements at the start of the cut. The straw oxide finish provides mild lubricity and corrosion resistance during storage and use. At 5.375 inches overall length with a 3.9375-inch flute, this bit fits standard drill chucks via its straight cylindrical shank. It is intended for general-purpose heavy-duty production and maintenance drilling.

This drill bit is suited for metal fabrication shops, maintenance and repair operations, and field work where steel, cast iron, non-ferrous metals, and high-temperature alloys are encountered. Its 9xD flute-to-diameter ratio makes it appropriate for through-holes and deeper passes in a standard drill press, magnetic drill, or handheld drill motor. The right-hand cutting direction is standard for conventional drilling operations. The series R10CO-R15CO-R18CO designation covers this cobalt jobber line across multiple diameter ranges. Primary workpiece material codes P, M, K, N, and S indicate suitability for steel, stainless, cast iron, non-ferrous, and heat-resistant alloys.

Key Features

• Cobalt high-speed steel construction for increased heat and wear resistance in hard materials
• 135-degree split point with web thinning reduces thrust and minimizes bit walking on entry
• Straw oxide finish provides surface lubricity and corrosion protection
• Straight cylindrical shank at 0.4219 inches diameter fits standard drill chucks without adapters
• Regular spiral, 2-flute design promotes chip evacuation in steel and similar materials
• Meets ANSI and NAS 907 standards for jobber-length drill geometry

Compatibility

Part of the PRECISION TWIST DRILL Series R10CO-R15CO-R18CO cobalt jobber line. Compatible with any standard drill press, magnetic base drill, or handheld drill motor that accepts a straight-shank bit in the 27/64-inch diameter range. Suitable for use on steel, stainless steel, cast iron, non-ferrous metals, and heat-resistant alloys as indicated by workpiece material codes P, M, K, N, and S.

Installation Notes

This bit is installed and operated by machinists, tool-and-die technicians, HVAC and plumbing tradespeople, and general maintenance mechanics. Secure the shank fully in the drill chuck before operation and confirm the chuck key is removed before starting the machine. Use cutting fluid or oil when drilling steel to extend tool life and maintain hole quality. Inspect the cutting edges for wear or chipping before each use and replace the bit when point geometry is degraded to avoid workpiece damage or bit breakage.