Precision Twist Drill 5999557 Reduced Shank Drill Bit

Product Description

The PRECISION TWIST DRILL 5999557 is a reduced shank drill bit designed for drilling large-diameter holes using a standard 1/2 inch chuck. The cutting diameter measures 1.1719 inches (1-11/64 inch) while the Weldon flat shank reduces to 1/2 inch, allowing use in common drill chucks and milling machine spindles without requiring a large-capacity chuck. Manufactured from high-speed steel with a bright uncoated finish, this bit features a 118-degree standard point angle and right-hand spiral fluting. It is part of the Series R57 line and weighs approximately 0.5 pounds. Machinists, tool-and-die technicians, and maintenance professionals rely on this geometry for precise, repeatable hole entry in production and job-shop environments.

This drill bit is suited for drilling into a wide range of workpiece materials including alloy steel, carbon steel, cast iron, aluminum, aluminum alloys, brass, bronze, copper, magnesium, magnesium alloys, austenitic and ferritic grades, hardened steel, high strength bronze, case carburising steel, alloyed titanium, cermet, and lamellar graphite. The reduced shank design makes it practical in machine shops, fabrication facilities, and maintenance operations where large-bore holes are required but large-capacity chucks are not available. The 3-flat Weldon shank prevents slipping under torque load, which is especially important at this cutting diameter.

Key Features

• 1.1719 inch (1-11/64 inch) cutting diameter with a 1/2 inch reduced Weldon flat shank for standard chuck compatibility
• 118-degree standard point angle for clean entry on a broad range of ferrous and non-ferrous materials
• High-speed steel construction provides durability across general-purpose drilling applications
• 3-flat Weldon shank prevents rotational slipping under high torque loads
• Spiral flute length of 3 inches with 6 inch overall length supports drilling depths up to 3 inches
• Bright uncoated finish; ANSI-standard geometry, Series R57

Compatibility

Designed as an OEM-style reduced shank drill bit compatible with 1/2 inch capacity drill chucks and Weldon-style end mill holders in milling machines and drill presses. Suitable for use on the broad range of primary workpiece materials listed in the specifications section.

Installation Notes

Installation and use of this bit should be performed by a qualified machinist or maintenance technician familiar with drilling operations. Secure the Weldon flat shank firmly in a properly sized chuck or end mill holder, ensuring the set screw engages the flat to prevent slipping. Power down and lock out the machine spindle before changing tooling. Operate at the appropriate surface footage and feed rate for the workpiece material; consult published HSS speed-and-feed tables for the specific material being drilled.