Precision Twist Drill 5999931 Reduced Shank Drill Bit

Product Description

The PRECISION TWIST DRILL 5999931 is a reduced shank cobalt drill bit designed for drilling into ferrous metals and a wide range of secondary materials including aluminum, copper, nickel, titanium, and synthetic materials. The bit measures 59/64 inches (0.921 inches) in diameter with a 1/2-inch straight-cylindrical shank, allowing it to be chucked in standard 1/2-inch drill chucks despite its larger cutting diameter. The 118-degree split point promotes accurate starts and reduces thrust. Overall length is 6 inches with a 3-inch flute length and a bright, uncoated finish. This is a professional-grade tool intended for use by machinists, maintenance technicians, and fabricators.

This bit belongs to the Series R56CO line of reduced shank cobalt drills. It is suited for production and maintenance drilling applications where a large-diameter hole is required but the available equipment is limited to a 1/2-inch chuck. Typical applications include drilling ferrous metal plate, structural steel, and similar hard materials in shop or field environments. The cobalt construction provides heat resistance for demanding drilling conditions without requiring coolant, though dry drilling performance depends on feed rate and material hardness.

Key Features

• 59/64-inch (0.921-inch) cutting diameter with a reduced 1/2-inch shank for compatibility with standard 1/2-inch chucks
• Cobalt tool material provides elevated heat and wear resistance versus standard high-speed steel
• 118-degree split point for self-centering starts and reduced feed pressure
• Right-hand cut with regular spiral flutes for efficient chip evacuation
• 3-inch flute length supports drilling depths up to 3 inches
• Bright/uncoated finish; no coolant required per design specification
• Meets ANSI standards; Series R56CO

Compatibility

Designed for use with any drill press, mag drill, or hand drill equipped with a 1/2-inch chuck. Primary workpiece material is ferrous metal; rated for secondary use on aluminum, cermet, copper, magnesium, nickel, synthetic, and titanium materials per manufacturer specifications.

Installation Notes

Secure the 1/2-inch shank firmly in a properly rated chuck before operation. Ensure the workpiece is clamped or fixtured to prevent rotation during drilling. Select appropriate feed rate and spindle speed for the workpiece material to avoid overheating the cutting edge. Inspect the bit for wear or chipping before each use; a dull or damaged cobalt bit should be replaced or professionally resharpened.