Precision Twist Drill 5998330 No. 21 Hss Jobber Drill Bit

Product Description

The PRECISION TWIST DRILL 5998330 is a jobber-length twist drill bit in wire gauge size No. 21 (0.1590 inches decimal), designed for general-purpose drilling in metal and other hard materials. The bit is manufactured from high speed steel with a steam oxide coating that reduces friction and provides light corrosion resistance during storage. It features a 118-degree standard point angle with a web-thinned, tapered web design for improved chip clearance and easier starting. Overall length is 3.25 inches with a 2.125-inch spiral flute length. Right-hand cut, regular spiral, and a straight-cylindrical shank round out the standard jobber configuration. Licensed machinists, maintenance technicians, and metal fabricators use this size regularly.

This bit is suited for drilling steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium in both production and maintenance-repair applications. The No. 21 wire size is commonly used for tapping operations and precision hole work in sheet metal and structural steel. The 13xD flute-to-diameter ratio and 2.125-inch maximum drilling depth make it a practical choice for through-hole and blind-hole work on benchtop drill presses and hand-held drills in shop and field settings. It is part of Precision Twist Drill Series R18 and conforms to ANSI standards.

Key Features

• Wire gauge size No. 21 — 0.1590-inch decimal diameter
• High speed steel construction with steam oxide finish for reduced friction
• 118-degree standard point angle with web-thinned, tapered web for easier entry
• Right-hand cut with regular spiral flute, 2.125-inch flute length
• Straight-cylindrical shank, 0.1590-inch shank diameter, 1.125-inch shank length
• Conforms to ANSI specifications; Series R18 general-purpose rating

Compatibility

Designed as a general-purpose jobber-length replacement drill bit compatible with standard drill chucks and drill presses that accept straight-cylindrical shanks in the 0.1590-inch diameter range. Rated for use in steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium workpiece materials per material codes P, M, K, N, and S.

Installation Notes

Install in a standard keyed or keyless drill chuck and verify the shank is fully seated before drilling. Power down or unplug the drill before changing bits. Use cutting fluid or coolant when drilling stainless steel, superalloys, or titanium to preserve edge life; this bit does not support coolant-through delivery. Follow shop safety practices and applicable ANSI standards for drilling operations.