Hertel 74131376 Cobalt Screw Machine Drill Bit Letter Z

Product Description

The HERTEL 74131376 is a cobalt screw machine length drill bit sized to letter Z (0.4130 inches decimal equivalent) with a 135-degree split point and web-thinned tip geometry. Screw machine length bits are shorter than jobber-length bits, which reduces deflection and improves rigidity in tight drilling applications. The split point starts on contact without a center punch and reduces thrust. Two regular spiral flutes evacuate chips efficiently. The straw finish is standard for high-speed cobalt steel and indicates the heat treatment applied during manufacturing. This bit is suited for machinists, maintenance mechanics, and metalworking tradespeople drilling steel, stainless, cast iron, and other ferrous and hard materials.

Screw machine length cobalt drill bits are commonly used in CNC machining centers, drill presses, and hand-held drilling operations where short tool overhang and high rigidity are required. The letter Z size at 0.4130 inches is frequently used for tapping preparation, close-tolerance hole drilling, and production metalworking where consistent hole diameter is critical. The straight cylindrical shank fits standard drill chucks without modification.

Key Features

• Letter Z size at 0.4130 inches decimal equivalent for close-tolerance drilling
• 135-degree split point with web thinning for self-centering starts and reduced thrust
• Cobalt high-speed steel (HSCO) construction for heat and wear resistance in hard materials
• Screw machine length overall at 3.375 inches for improved rigidity and reduced deflection
• 2-inch flute length with regular spiral and parallel web configuration for consistent chip evacuation
• Right-hand cutting, straight shank - fits standard drill chucks

Compatibility

Designed as a screw machine length drill bit for use in standard drill chucks accepting straight cylindrical shanks, compatible with drill presses, CNC machining centers, and hand-held drills within the 0.4000 to 0.4500 inch drill bit size range.

Installation Notes

Installation and use of this drill bit should be performed by qualified machinists or metalworking tradespeople familiar with proper cutting speeds and feeds for cobalt tooling. Secure the straight shank firmly in a calibrated drill chuck before operation and verify runout is within acceptable limits. Use appropriate cutting fluid for the workpiece material to extend tool life and maintain hole quality. Inspect the cutting edges before each use and replace the bit if chipping or excessive wear is observed.