Hertel 79892774 Solid Carbide Jobber Drill Bit Letter X

Product Description

The HERTEL 79892774 is a jobber-length drill bit ground from solid carbide and sized to Letter X, equal to 0.3970 inches in diameter. It features a 118-degree standard point with web thinning on a tapered web, a regular spiral flute configuration, and a bright (uncoated) finish. The straight-cylindrical shank measures 0.3970 inches in diameter for direct chuck compatibility. At 4.5 inches overall length with a 2.875-inch flute length, this bit suits precision drilling operations where carbide hardness and dimensional accuracy are critical. It is rated Material Grade C2 and carries a High Performance grade designation. Diameter tolerance is held to -0.0005 to 0.0000 inches for consistent, on-size holes.

This bit is suited for production and maintenance drilling in ferrous and non-ferrous metals, plastics, and composite materials where solid carbide is specified over high-speed steel. Typical applications include precision hole-making in machining centers, drill presses, and CNC setups. The right-hand cut and two-flute spiral geometry support efficient chip evacuation in through-hole and blind-hole drilling. The Letter X size fits applications requiring a 0.3970-inch bore, which is common as a pre-tap or reaming undersize in several thread series.

Key Features

• Solid carbide construction for superior hardness and wear resistance versus high-speed steel bits
• 118-degree standard point with web thinning for reduced thrust and cleaner entry
• Tapered web configuration contributes to bit rigidity over the full flute length
• Bright finish retained for applications where coating is not required or desired
• Diameter tolerance of -0.0005 to 0.0000 inches ensures on-size holes without secondary reaming in many applications
• Straight-cylindrical shank fits standard Jacobs-style and collet chucks without adapters

Compatibility

Designed as a jobber-length solid carbide drill bit for use in any machine tool spindle or hand-held drill accepting a straight-cylindrical shank at 0.3970 inches in diameter, including drill presses, milling machines, and CNC machining centers.

Installation Notes

Installation and use should be performed by a qualified machinist or tool-and-die professional familiar with carbide tooling. Solid carbide bits are brittle compared to high-speed steel and can fracture if subjected to side loads, interrupted cuts without proper support, or excessive runout in the chuck or collet. Always confirm spindle runout is within acceptable limits before seating the bit, and secure the shank fully in the chuck or collet before starting the spindle. Do not use carbide drills in hand-held portable drills where lateral deflection cannot be controlled.