Precision Twist Drill 5999606 Reduced Shank Drill Bit

Product Description

The PRECISION TWIST DRILL 5999606 is a reduced shank drill bit engineered for drilling large-diameter holes with a standard 1/2-inch shank setup. The bit measures 1.2188 inches (1-7/32 inches) in diameter and runs 6 inches overall, with a 3-inch flute length and a 3-inch maximum drilling depth. Built from high-speed steel (HSS) with a bright, uncoated finish, it uses a 118-degree standard point angle and a right-hand spiral flute for consistent chip evacuation. The Weldon flat shank with three flats provides positive drive and eliminates slippage in compatible tool holders. This bit suits machinists, fabricators, and trade professionals working in shops or field environments.

The 5999606 is suited for production drilling and maintenance applications where oversized holes are required but the machine spindle or chuck is limited to a 1/2-inch shank. The reduced shank design allows this 1.2188-inch bit to be used in standard drill presses, milling machines, or power tools equipped with a 1/2-inch chuck or Weldon-style holder. Compatible primary workpiece materials include alloy steel, alloyed titanium, aluminum, aluminum alloy, brass, bronze, carbon steel, cast iron, copper, magnesium, magnesium alloy, and hardened steel, among others. Series R57 designates this as a general-purpose spiral-flute geometry with a regular spiral configuration.

Key Features

• 1.2188-inch (1-7/32-inch) cutting diameter with reduced 1/2-inch shank for broad machine compatibility
• 118-degree standard point angle for reliable self-centering on a wide range of metals
• High-speed steel construction provides adequate hardness and toughness across common workpiece materials
• Weldon flat shank with three flats prevents rotational slippage under torque load
• Bright uncoated finish maintains dimensional accuracy and suits general-purpose use without added coating cost
• Right-hand, regular spiral flute design promotes efficient chip removal during through-hole and blind-hole drilling

Compatibility

Designed for use in drill presses, milling machines, and similar equipment fitted with a 1/2-inch Weldon-style or standard chuck. Suitable for drilling alloy steel, carbon steel, cast iron, aluminum, brass, bronze, copper, magnesium, hardened steel, and related metals as specified in the product data.

Installation Notes

Installation and operation should be performed by a qualified machinist or trained trade professional. Secure the Weldon flat shank firmly in a compatible holder so all three flats are properly engaged before operation. Power down and de-energize all equipment before changing bits or adjusting tool holders. Do not exceed the rated drilling depth of 3 inches, and use appropriate cutting fluid or coolant practices per shop safety standards, noting this bit is rated for dry cutting without integrated coolant.