Precision Twist Drill 5998995 Cobalt Jobber Drill Bit Letter B

Product Description

The PRECISION TWIST DRILL 5998995 is a cobalt jobber-length drill bit sized to Letter B (0.2380 inches) with a 135-degree split-point geometry and web-thinned tip. Built from cobalt high-speed steel and finished with an oxide/bronze straw coating, it is engineered for heavy-duty drilling in ferrous metals, stainless, and high-strength alloys. The two-flute right-hand spiral design promotes chip evacuation during through-hole and blind-hole operations. At 4.0 inches overall length with a 2.75-inch flute, this bit fits standard drill chucks and magnetic-base drill units without modification. It meets ANSI and NAS 907 specifications, making it suitable for aerospace and precision fabrication environments.

This bit is used in metalworking applications involving steel, cast iron, aluminum, non-ferrous metals, and specialty alloys as indicated by the primary workpiece material codes P, M, K, N, and S. It is a general-purpose heavy-duty tool suited for maintenance technicians, millwrights, pipefitters, and fabrication shops that drill pilot holes, clearance holes, and production runs in structural and sheet metal. The 12xD flute-to-diameter ratio supports moderate drilling depth without step-drilling on most production gauges.

Key Features

• Cobalt HSS construction for improved heat and wear resistance in hard metals
• 135-degree split point with web thinning reduces walking and lowers thrust on entry
• Oxide/bronze straw coating extends tool life in abrasive and high-temperature cuts
• Right-hand spiral, regular flute for reliable chip clearance in through and blind holes
• Straight cylindrical shank (0.2380 inches diameter) fits standard 3-jaw drill chucks
• Meets ANSI and NAS 907 standards for dimensional and performance consistency

Compatibility

Designed as an OEM-style replacement and general-purpose jobber drill for use in any standard drill press, hand drill, or magnetic-base drill accepting a straight-shank bit in the Letter B size range.

Installation Notes

Installation and use of this bit is performed by machinists, maintenance technicians, pipefitters, and fabricators using drill presses, magnetic-base drills, or hand-held power drills. Secure the straight shank fully in a properly sized chuck and tighten all jaws evenly before operation. Always use cutting fluid or coolant when drilling steel and hard alloys to protect both the bit and the workpiece. Inspect the cutting edges for wear before each use and replace the bit if chipping or rounding is observed at the tip.