Precision Twist Drill 5998152 Cobalt Jobber Drill 21/32 in

Product Description

The PRECISION TWIST DRILL 5998152 is a cobalt high-speed steel jobber-length drill bit designed for heavy-duty drilling in ferrous and non-ferrous metals. It measures 21/32 inches (0.6563 inches decimal) in diameter with a 7.125-inch overall length and a 5.1875-inch flute length. The 135-degree split point reduces walking and requires less thrust than a standard 118-degree point. A straw oxide finish provides mild lubricity and corrosion resistance during metal-cutting operations. The web-thinned, tapered-web construction improves chip evacuation and cutting efficiency. This bit is installed by machinists, maintenance technicians, and metalworking trades across drilling, fabrication, and production environments.

Intended for drilling steel, cast iron, aluminum, and similar workpiece materials, this jobber drill is suited for both production and maintenance drilling applications. The straight cylindrical shank fits standard drill chucks on drill presses, lathes, and hand-held power tools. With a flute-to-diameter ratio of 8xD, it handles moderate drilling depths up to 5.1875 inches in a single pass where chip clearance permits. It meets NAS 907 and ANSI dimensional standards, making it appropriate for aerospace-adjacent and general industrial environments where specification compliance is required. It is sold as a single unit.

Key Features

• Cobalt high-speed steel construction for elevated heat and wear resistance in ferrous metal drilling
• 135-degree split point reduces drill walking and lowers required feed pressure
• Web-thinned, tapered-web design promotes chip evacuation and reduces thrust load
• Straw oxide coating adds surface lubricity and mild corrosion protection
• Right-hand cutting with regular spiral flute geometry for standard drilling operations
• Meets NAS 907 and ANSI standards for dimensional accuracy and performance

Compatibility

Part of the R10CO-R15CO-R18CO series. Straight cylindrical shank diameter of 0.6563 inches fits any drill chuck rated for 21/32-inch straight-shank tooling. Suitable for use in drill presses, milling machines, lathes, and heavy-duty hand drills.

Installation Notes

Install in a properly rated drill chuck and tighten with a chuck key before operation. Ensure the workpiece is securely fixtured before drilling to prevent movement and bit breakage. Coolant-through is not supported on this bit; apply cutting fluid externally when drilling hard steels to extend tool life and manage heat. Follow applicable ANSI and shop safety standards when operating rotating cutting tools.