Precision Twist Drill 5999040 Cobalt Jobber Drill Bit M

Product Description

The PRECISION TWIST DRILL 5999040 is a cobalt jobber-length drill bit sized to Letter M (0.2950 inches) with a 135-degree split point and a straw oxide finish. Built from cobalt high-speed steel and rated for heavy-duty general-purpose drilling, it handles steel and other demanding materials where standard HSS bits wear prematurely. The 135-degree point reduces walking on entry and requires no center punch on most flat surfaces. A regular spiral flute with web thinning promotes chip evacuation and reduces thrust. This bit is installed and used by machinists, maintenance technicians, and metal fabricators working in production or field environments.

This jobber drill is suited for drilling steel, cast iron, stainless, nonferrous alloys, and similar materials in both production and maintenance applications. The straight cylindrical shank fits standard three-jaw drill chucks on drill presses, lathes, and hand drills. With a flute-to-diameter ratio of 10xD, it is well matched to moderate-depth through-holes and blind holes in typical structural and plate steel work. The Series R10CO-R15CO-R18CO designation places this bit within a heavy-duty cobalt jobber family built to NAS 907 and ANSI standards.

Key Features

• Letter M size — 0.2950 inches diameter with matching straight shank
• 135-degree split point reduces walking and lowers required thrust
• Cobalt HSS construction for heat resistance and extended tool life in steel
• Straw oxide finish provides light lubricity and corrosion resistance
• Web-thinned tapered web for improved chip clearance and reduced feed force
• Meets NAS 907 and ANSI standards — suitable for aerospace and industrial specifications

Compatibility

Designed for use with standard drill chucks accepting a 0.2950-inch straight cylindrical shank. Compatible with primary workpiece materials coded P, M, K, N, and S — covering steel, stainless, cast iron, nonferrous metals, and superalloys per the Series R10CO-R15CO-R18CO specification.

Installation Notes

This bit is installed by machinists and maintenance trades in any chuck-equipped drilling machine — drill press, lathe tailstock, or portable drill. Secure the straight shank fully in the chuck and verify runout before beginning a cut. Use cutting fluid or coolant when drilling steel to extend bit life, noting this bit does not support coolant-through delivery. Inspect the cutting edges and web condition before each use; a worn or chipped point should be reground or the bit replaced before returning to service.