Precision Twist Drill 5998257 Jobber Drill Bit No. 28

Product Description

The PRECISION TWIST DRILL 5998257 is a jobber-length drill bit designed for general-purpose drilling in a wide range of materials. It carries a No. 28 wire gauge designation, equivalent to a 9/64 inch (0.1405 inch decimal) diameter, and features a 118-degree standard point angle ground to a bright, uncoated finish. The two-flute spiral design with a tapered web and web-thinned point reduces thrust and improves chip evacuation. Made from high speed steel, this bit is suited for production or maintenance drilling performed by machinists, tool-room technicians, and general trade professionals.

This drill bit is intended for use on steel, cast iron, non-ferrous metals, superalloys, and titanium in standard drilling applications. With a 2.875-inch overall length and a 1.75-inch flute length, it fits standard drill chucks and handheld power tools used in maintenance, fabrication, and light manufacturing environments. The straight cylindrical shank diameter matches the drill diameter at 0.1405 inches, allowing secure chuck engagement without adapters. It is packaged and sold individually and is part of the R10H-R18H series.

Key Features

• No. 28 wire gauge size — 9/64 inch (0.1405 inch) diameter for precise hole sizing
• 118-degree standard point angle for general-purpose entry in ferrous and non-ferrous stock
• High speed steel construction for durability across a broad range of workpiece materials
• Web-thinned, tapered web design reduces drilling thrust and extends bit life
• Bright uncoated finish — compatible with cutting fluids without coating interference
• Right-hand spiral flute with regular helix promotes consistent chip removal
• ANSI standard compliance for dimensional consistency

Compatibility

Designed as a general-purpose jobber-length drill bit compatible with standard three-jaw drill chucks accepting a straight cylindrical shank. Rated for drilling steel, cast iron, non-ferrous metals, superalloys, and titanium per workpiece material codes P, K, N, and S. Part of the R10H-R18H series.

Installation Notes

Install in a standard drill chuck, ensuring the shank is fully seated and the chuck is tightened securely before operation. Power down or de-energize any machine tool before changing bits. Apply appropriate cutting fluid for ferrous workpieces to manage heat and extend bit life. Drilling depth should not exceed the rated maximum flute depth of 1.75 inches in a single pass without chip-clearing cycles.