Precision Twist Drill 5999033 Cobalt Jobber Drill Bit K

Product Description

The PRECISION TWIST DRILL 5999033 is a cobalt high-speed steel jobber-length drill bit sized at Letter K (0.2812 inches, 9/32 inch). It features a 135-degree split point with web thinning for fast, accurate starts without center-punching on most materials. The straw oxide finish reduces friction and provides light corrosion resistance during storage and use. Two regular spiral flutes with a tapered web configuration clear chips efficiently in through-hole drilling applications. This bit is ground to ANSI standards and carries a NAS 907 specification designation, making it suitable for demanding production and maintenance drilling in steel and a range of other workpiece materials.

This jobber drill is designed for general-purpose heavy-duty drilling in steel, stainless, cast iron, nonferrous metals, and high-temp alloys, as classified by primary workpiece material codes P, M, K, N, and S. The 4.25-inch overall length and 2.9375-inch flute length cover standard through-hole and moderate-depth drilling tasks in both shop and field environments. It is sold individually and fits standard drill chucks accepting a 0.2813-inch straight cylindrical shank. Machinists, maintenance technicians, pipefitters, and ironworkers commonly use bits in this size range for structural, mechanical, and fabrication drilling work.

Key Features

• Cobalt high-speed steel construction for increased heat resistance when drilling hard metals
• 135-degree split point with web thinning for reduced thrust and self-starting entry
• Straw oxide finish reduces friction and provides light protection against corrosion
• Regular spiral flutes with tapered web for efficient chip evacuation in through-hole drilling
• Straight cylindrical shank fits standard drill chucks without adapters
• Ground to ANSI standards with NAS 907 specification designation for dimensional consistency

Compatibility

Part of the R10CO-R15CO-R18CO series. Fits any drill chuck or collet accepting a 0.2813-inch straight shank. Suitable for drilling steel, stainless alloys, cast iron, nonferrous metals, and high-temperature alloys per material codes P, M, K, N, and S.

Installation Notes

Install in a keyed or keyless chuck rated for the shank diameter and secure firmly before use. Confirm the workpiece is clamped or fixtured to prevent movement during drilling. Use appropriate cutting fluid or coolant when drilling hard steels or stainless to extend tool life; this bit does not support coolant-through delivery. Inspect the cutting edges and point for chipping or wear before each use and replace if the geometry is compromised.