Hertel 74131293 Screw Machine Drill Bit Letter R Cobalt

Product Description

The HERTEL 74131293 is a screw machine length (stub-length) cobalt drill bit sized to Letter R (0.3390 inches) with a 135-degree split point. Cobalt construction provides heat resistance for drilling through harder steels, stainless, and high-alloy materials where standard high-speed steel bits work-harden or wear prematurely. The split point geometry reduces walking on entry, eliminating the need for a center punch on most flat surfaces. At 3.0 inches overall length, this stub-length format offers greater rigidity than jobber-length bits, reducing deflection in tight-clearance or high-feed applications. Intended for use by machinists, tool-and-die tradespeople, and maintenance technicians on manual or CNC drilling operations.

This bit is suited for production drilling in metalworking environments where hole accuracy and tool life are priorities. Screw machine length drill bits are commonly used in drill presses, lathes, and machining centers where stub-length rigidity is required. Typical applications include drilling bolt clearance holes, tapping preparation, and reaming pre-holes in ferrous and non-ferrous metals. The right-hand cutting direction and regular spiral flute are standard for conventional drilling setups.

Key Features

• Letter R size - 0.3390 inches decimal equivalent
• 135-degree split point reduces entry walking and lowers thrust force
• Cobalt (HSCo) construction for heat resistance in hard and abrasive metals
• Screw machine (stub) length at 3.0 inches OAL for increased rigidity and reduced deflection
• Web-thinned parallel web for improved chip clearance and cutting efficiency
• Straight cylindrical shank fits standard drill chucks without adapters
• Right-hand cut, regular spiral flute - compatible with conventional drilling setups

Compatibility

Designed as a standard screw machine length drill bit for use in drill presses, machining centers, lathes, and hand-held power drills equipped with a chuck sized for a straight cylindrical shank. Fits within the 0.3000 to 0.3500 inch drill bit size range category.

Installation Notes

Installation and use should be performed by qualified machinists or maintenance technicians familiar with metal cutting operations. Secure the shank fully in the chuck and verify runout before drilling. Power down the machine and lock out energy sources before changing bits or clearing chips. Do not exceed the recommended feed and speed parameters for the workpiece material and bit diameter.