Precision Twist Drill 5999327 Jobber Drill Bit No. 21

Product Description

The PRECISION TWIST DRILL 5999327 is a jobber-length twist drill bit in wire gauge size No. 21 (0.1590 inches decimal), ground from high speed steel and finished with a steam oxide coating. It features a standard 118-degree split-point angle, two spiral flutes in a regular helix, and a straight cylindrical shank. Overall length is 3.25 inches with a flute length of 2.125 inches. The web-thinned, tapered web geometry reduces thrust at entry, making this bit well-suited for production drilling and general maintenance work across a wide range of workpiece materials.

This bit is designed for drilling steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium in general-purpose applications. It fits standard drill chucks and is commonly used in machine shops, fabrication environments, and field maintenance where consistent hole quality in wire-gauge diameters is required. Right-hand cutting direction is standard for conventional drill press, hand drill, and CNC spindle operation. The Series R18A designation places it within the R10A-R15A-R18A family of jobber-length bits from Precision Twist Drill.

Key Features

• Wire gauge No. 21 size — 0.1590 inches decimal diameter
• 118-degree standard point angle with web-thinned, tapered web for reduced thrust
• High speed steel construction for durability across ferrous and non-ferrous materials
• Steam oxide coating helps resist heat buildup and corrosion during cutting
• 2-flute regular spiral flute for efficient chip evacuation — maximum drilling depth 2.125 inches
• Straight cylindrical shank fits standard 3-jaw chucks without adapters
• Meets ANSI and NAS 907 standards

Compatibility

Designed as an OEM-style replacement and general-purpose jobber drill bit for use in standard drill chucks accepting a 0.1590-inch straight cylindrical shank, compatible across the R10A, R15A, and R18A series per ANSI and NAS 907 specifications.

Installation Notes

Installation and use should be performed by machinists, maintenance technicians, or qualified tradespeople familiar with rotating cutting tools. Ensure the drill press, hand drill, or CNC spindle is powered down and locked out before inserting or removing the bit from the chuck. Secure the workpiece firmly before drilling, and apply appropriate cutting fluid when working with stainless steel, superalloys, or titanium to extend tool life and maintain hole quality.