Precision Twist Drill 5999631 Reduced Shank Drill Bit

Product Description

The PRECISION TWIST DRILL 5999631 is a reduced shank drill bit designed for general-purpose drilling in ferrous metals and a wide range of secondary materials. Built from high speed steel with a bright, uncoated finish, it delivers reliable performance in production and maintenance environments. The bit features a 13/16-inch cutting diameter paired with a 1/2-inch Weldon shank, allowing it to seat in standard 1/2-inch chucks and holders without slipping. A 118-degree standard point angle suits the majority of common drilling applications. This is a right-hand cut bit from the PRECISION TWIST DRILL R57 series.

This drill bit is suited for use in ferrous metal fabrication, HVAC sheet metal work, plumbing rough-in, and general mechanical contracting where a reduced shank profile is needed to adapt a larger cutting diameter to a 1/2-inch capacity drill or mill. Secondary workpiece materials include aluminum, copper, magnesium, nickel, titanium, and synthetic materials, making it versatile across trade and light industrial applications. The Weldon shank with three flats prevents rotation in the holder under load, which is important in high-torque drilling situations.

Key Features

• 13/16-inch (0.8125-inch) cutting diameter with a 1/2-inch reduced Weldon shank for use in standard 1/2-inch holders
• Three-flat Weldon shank prevents bit rotation under load
• 118-degree standard point angle for general-purpose entry into ferrous and non-ferrous materials
• 3-inch flute length with regular spiral flutes for efficient chip evacuation
• High speed steel construction provides durability across a broad range of workpiece materials
• Bright, uncoated finish — no coating buildup to affect tolerances

Compatibility

Designed for use with 1/2-inch Weldon-style drill chucks and milling holders. Compatible primary workpiece material is ferrous metal; secondary materials include aluminum, cermet, copper, magnesium, nickel, synthetic, and titanium. Conforms to ANSI standards. Part of the PRECISION TWIST DRILL R57 series.

Installation Notes

Install this bit into a Weldon-style holder, ensuring the set screw seats firmly against one of the three shank flats before applying torque. Power down or de-energize any drill press, mill, or power tool before changing bits. Secure the workpiece properly before drilling to prevent movement. Always wear appropriate eye protection and follow applicable shop safety standards when operating rotary cutting tools.