Precision Twist Drill 5999051 Cobalt Jobber Drill Bit Letter P

Product Description

The PRECISION TWIST DRILL 5999051 is a cobalt jobber-length drill bit sized to Letter P (0.3230 inches) for demanding metal drilling applications. It features a 135-degree split point with web thinning, which reduces walking on entry and lowers thrust requirements compared to a standard 118-degree point. The straw oxide finish provides mild lubricity and heat resistance during high-speed drilling into steel and other ferrous materials. Two regular spiral flutes clear chips efficiently over a flute length of 3.3125 inches. A straight cylindrical shank with zero flats accepts standard three-jaw drill chucks. This bit is sized for professional metalworking, maintenance, and fabrication use and is installed by machinists, millwrights, and skilled tradespeople.

This jobber drill is suited for drilling steel, cast iron, non-ferrous metals, and high-temperature alloys. The cobalt construction handles harder workpiece materials where standard HSS bits lose edge life quickly. Typical applications include structural steel fabrication, equipment repair, and production drilling where a repeatable hole diameter of 0.3230 inches is required. The series R10CO-R15CO-R18CO designation covers the cobalt oxide-coated jobber line from Precision Twist Drill. Overall length is 4.625 inches, making it compatible with standard drill press and handheld power drill setups where reach is not a limiting factor.

Key Features

• Letter P diameter — 0.3230 inches — for precise, repeatable hole sizing
• Cobalt construction for superior heat resistance and edge retention in steel and hard alloys
• 135-degree split point with web thinning reduces walking and lowers feed pressure
• Straw oxide coating adds lubricity and mild corrosion protection during use
• Regular spiral flute geometry promotes efficient chip evacuation at standard feed rates
• Meets ANSI and NAS 907 standards for dimensional accuracy and geometry

Compatibility

Part of the Precision Twist Drill Series R10CO-R15CO-R18CO cobalt oxide jobber line. Fits any standard three-jaw chuck accepting a 0.3230-inch straight cylindrical shank. Rated for primary workpiece material codes P, M, K, N, and S, covering steel, stainless, cast iron, non-ferrous metals, and high-temperature alloys per ISO material classification.

Installation Notes

Installation and use should be performed by qualified machinists or tradespeople familiar with drill press or power drill operation. Secure the shank fully in a properly sized chuck and verify runout before drilling. Apply cutting fluid appropriate to the workpiece material to extend tool life and maintain hole quality. Do not exceed the maximum drilling depth of 3.3125 inches in a single pass without retracting to clear chips.