Precision Twist Drill 5999072 Cobalt Jobber Drill Bit U

Product Description

The PRECISION TWIST DRILL 5999072 is a cobalt jobber-length drill bit sized to Letter U (0.3680 inches decimal equivalent) and engineered for heavy-duty drilling in steel and other demanding workpiece materials. The 135-degree split point reduces walking at contact and lowers the thrust needed to start a hole, making it well suited to production and maintenance drilling environments. A straw oxide finish provides mild lubricity and heat resistance during cutting. The straight cylindrical shank and regular spiral fluting are machined to ANSI standards, and the web is thinned and tapered to improve chip evacuation in deep-hole applications. Licensed HVAC technicians, pipefitters, electricians, and general metalworking shops all rely on this bit class for everyday drilling tasks in ferrous materials.

This jobber drill is intended for right-hand drilling in steel, cast iron, aluminum, non-ferrous metals, and similar materials covered by material codes P, M, K, N, and S. The 5-inch overall length and 3.625-inch flute length allow it to reach through typical structural members, pipe flanges, electrical enclosures, and HVAC sheet metal. It is part of the Series R10CO-R15CO-R18CO cobalt line and meets NAS 907 specification, making it appropriate wherever NAS-designated tooling is called out on a job sheet. Each package contains one bit.

Key Features

• Letter U size — 0.3680-inch decimal equivalent for close-tolerance hole sizing
• 135-degree split point reduces thrust and minimizes walking on hard surfaces
• Cobalt high-speed steel construction handles elevated cutting temperatures in steel and tough alloys
• Straw oxide finish provides lubricity and surface hardness without post-treatment costs
• Web-thinned, tapered web improves chip flow and reduces torque in deep cuts up to 3.625 inches
• Meets ANSI standards and NAS 907 specification for controlled tooling environments

Compatibility

Designed as a general-purpose jobber drill for right-hand drilling operations in steel, cast iron, non-ferrous metals, and similar materials (material codes P, M, K, N, S). Part of the PRECISION TWIST DRILL Series R10CO-R15CO-R18CO cobalt line.

Installation Notes

Install in a compatible drill chuck rated for a 0.3680-inch straight shank before use. Secure the workpiece fully before drilling and verify spindle speed against the recommended surface footage for cobalt tooling in the target material. Apply cutting fluid or oil when drilling steel to extend tool life and improve hole finish. Inspect the cutting edges for chipping or wear before each use — a damaged tip increases the risk of bit breakage and out-of-tolerance holes.