Precision Twist Drill 5998198 Cobalt Jobber Drill 35/64 in

Product Description

The PRECISION TWIST DRILL 5998198 is a cobalt jobber-length drill bit designed for heavy-duty drilling in ferrous and non-ferrous metals. Built to NAS 907 and ANSI standards, it features a 135-degree split point with web thinning for reduced thrust and faster penetration without a center punch. The straw oxide finish provides lubricity and mild heat resistance. At 6.625 inches overall length with a 4.8125-inch flute and a straight cylindrical shank sized at 0.5469 inches in diameter, this bit fits standard drill chucks and is suited for production and maintenance drilling environments.

This bit is intended for general-purpose drilling in steel and other metallic workpiece materials, covering material codes P, M, K, N, and S — spanning carbon steels, alloy steels, stainless steels, cast irons, non-ferrous metals, and heat-resistant superalloys. It is part of the R10CO-R15CO-R18CO series, which is optimized for shops and field technicians who need consistent performance across a range of metal stock. Typical users include machinists, millwrights, HVAC equipment fabricators, and mechanical contractors drilling structural and sheet metal components.

Key Features

• Cobalt high-speed steel construction for heat resistance and extended tool life in hard metals
• 135-degree standard point angle with web thinning for self-centering entry and reduced cutting force
• Straw oxide finish for added lubricity and corrosion resistance during storage and use
• Regular spiral flute with 9xD flute-to-diameter ratio for efficient chip evacuation in deeper holes
• Straight cylindrical shank at 0.5469 inches fits standard three-jaw drill chucks
• NAS 907 and ANSI specification compliance for dimensional consistency

Compatibility

Designed for use in standard drill chucks accepting a 0.5469-inch straight shank. Part of the PRECISION TWIST DRILL R10CO-R15CO-R18CO cobalt jobber drill series. Suitable for drilling steel and a broad range of metallic workpiece materials per NAS 907 designation.

Installation Notes

Installation is performed by machinists or maintenance technicians using a drill press, magnetic drill, or hand-held electric drill with a compatible chuck rated for the shank diameter. Secure the workpiece before drilling to prevent movement and ensure proper chip clearance during operation. Use cutting fluid or coolant appropriate for the workpiece material to extend tool life, as this bit does not support coolant-through delivery. Inspect the cutting edges before use and replace the bit if chipping or excessive wear is observed.