Precision Twist Drill 5998915 Screw Machine Drill Bit

Product Description

The PRECISION TWIST DRILL 5998915 is a screw machine length drill bit designed for high-performance drilling in tight-clearance and production environments. Sized at 0.257 inches (Letter F) in diameter, this bit is manufactured from high speed steel with a bright, uncoated finish. It features a standard 118-degree point angle, a spiral flute with a regular helix, and a straight-cylindrical shank for use in standard drill chucks and screw machine spindles. The web-thinned, tapered web construction reduces thrust load and improves chip evacuation. This bit is rated for general-purpose use and meets ANSI standards.

This drill bit is suited for screw machine operations, production drilling, and bench drill press work where a shorter flute length improves rigidity and reduces deflection. Its primary listed workpiece material is titanium, though the high speed steel construction also handles ferrous and non-ferrous metals common in trade and machine shop applications. The 2.5xD flute-to-diameter ratio and 1.4375-inch flute length make it appropriate for shallow-to-medium depth holes in controlled setups.

Key Features

• Letter F size: 0.257 inches diameter for precise fit in dimension-critical applications
• High speed steel construction provides toughness and heat resistance during drilling
• 118-degree standard point angle for general-purpose metal drilling
• Web-thinned, tapered web reduces thrust and improves chip flow
• Screw machine length body improves rigidity and reduces runout in short-reach setups
• Bright, uncoated finish — compatible with cutting fluids and standard coolant-free dry drilling
• Meets ANSI standards; Series R42 designation

Compatibility

Designed as a direct-fit screw machine length drill bit for use in standard straight-shank drill chucks, screw machine spindles, and drill press setups where a 0.257-inch (Letter F) diameter bit is specified.

Installation Notes

Installation and use of this bit should be performed by a qualified machinist or tool operator. Secure the straight-cylindrical shank fully in the chuck and verify concentricity before running at speed. Apply appropriate cutting fluid when drilling titanium or hardened ferrous metals to extend tool life and prevent work hardening. Inspect the cutting edges before each use and do not run a chipped or dull bit at full feed rate.