Precision Twist Drill 5998217 Cobalt Jobber Drill 5/8 in

Product Description

The PRECISION TWIST DRILL 5998217 is a cobalt jobber-length drill bit designed for demanding metal-cutting applications. Built to ANSI standards and meeting NAS 907 specification, it features a 135-degree split point with web thinning for reduced thrust and faster penetration on entry. The straw oxide finish improves lubricity and heat resistance during extended drilling cycles. At 7.125 inches overall length with a 5.1875-inch flute length, it fits standard drill chucks and magnetic drill press setups. This bit is a heavy-duty general-purpose tool installed by machinists, pipefitters, ironworkers, and mechanical contractors working with steel and ferrous materials.

The 5998217 is suited for production drilling in steel, stainless, cast iron, and other hard ferrous and non-ferrous alloys. Its regular spiral flute geometry handles through-hole and blind-hole work in structural steel, pipe, plate, and fabricated assemblies. The straight cylindrical shank accepts standard drill chucks without adapters, making it a practical fit for both bench drill presses and portable magnetic drills. It covers workpiece material classifications P, M, K, N, and S per standard tooling codes, giving it broad applicability across a range of metals encountered in trade and industrial settings.

Key Features

• Cobalt high-speed steel construction for high-heat, high-hardness drilling applications
• 135-degree split point with web thinning reduces walking and lowers required thrust
• Straw oxide finish improves surface lubricity and extends tool life in steel
• Regular spiral flute with tapered web configuration promotes chip evacuation
• Straight cylindrical shank fits standard drill chucks without modification
• Meets NAS 907 and ANSI standards for dimensional and performance compliance

Compatibility

Part of the R10CO-R15CO-R18CO series. Designed for general-purpose drilling in steel and comparable ferrous and non-ferrous materials classified under P, M, K, N, and S workpiece material codes.

Installation Notes

Installation of this drill bit is performed by machinists, ironworkers, and mechanical tradespeople using standard drill chucks on bench, floor, or magnetic drill presses. Ensure the drill press or driver is powered down and the chuck is fully disengaged before inserting or removing the bit. Use cutting fluid or coolant appropriate for cobalt tooling when drilling hard steel to maintain edge life. Do not exceed the recommended drilling depth of 5.1875 inches in a single pass without clearing chips to prevent flute binding.