Precision Twist Drill 5998356 Jobber Drill Bit Letter E

Product Description

The PRECISION TWIST DRILL 5998356 is a jobber-length drill bit sized at Letter E, equivalent to 0.250 inches (1/4 inches), made from high speed steel (HSS) with a bright, uncoated finish. It features a standard 118-degree split point and a two-flute regular spiral configuration with web thinning for reduced thrust during entry. The overall length is 4 inches with a 2.75-inch flute length, making it a general-purpose choice for production and maintenance drilling operations. Machinists, tool-and-die technicians, and general metalworking tradespeople are the primary users of this bit.

This drill bit is suited for right-hand drilling in steel, cast iron, non-ferrous metals, superalloys, and titanium. Its straight cylindrical shank measures 0.250 inches in diameter and 1.25 inches in length, compatible with standard drill chucks across benchtop drill presses, CNC machines, and handheld power tools. The tapered web configuration and web-thinned geometry support clean chip evacuation in deep-hole applications up to the maximum drilling depth of 2.75 inches. It is cataloged under Series R10H-R18H and meets ANSI standards.

Key Features

• Letter E size (0.2500 inches decimal) with straight cylindrical shank at 0.2500 inches diameter
• 118-degree standard point angle for general-purpose entry on steel and cast iron
• Two-flute regular spiral design with web-thinned, tapered web for lower cutting thrust
• Bright uncoated HSS construction suitable for a wide range of workpiece materials
• 4-inch overall length with 2.75-inch flute and 2.75-inch maximum drilling depth
• Conforms to ANSI specifications, Series R10H-R18H

Compatibility

Designed as a general-purpose jobber-length drill bit for use in steel, cast iron, non-ferrous metals, superalloys, and titanium workpieces. Fits any standard drill chuck accepting a 0.250-inch straight cylindrical shank.

Installation Notes

Secure the straight cylindrical shank firmly in a properly sized drill chuck before operation. Ensure the workpiece is clamped or fixtured to prevent movement during drilling. Apply appropriate cutting fluid when drilling steel, cast iron, or titanium to extend tool life and improve hole quality. Inspect the cutting edges for wear before each use and replace the bit if chipping or dulling is observed.