Precision Twist Drill 5998631 29/64 Screw Machine Drill Bit

Product Description

The PRECISION TWIST DRILL 5998631 is a screw machine length drill bit designed for high-performance drilling in demanding shop and field applications. Ground from high speed steel with a bright uncoated finish, this bit features a 29/64 inch (0.4531 inch) diameter, a standard 118-degree point angle, and a web-thinned tapered web for reduced thrust and cleaner entry. The straight-cylindrical shank seats securely in standard drill chucks. At 3-9/16 inches overall length with a 2-1/8 inch flute, the stub-length body provides added rigidity compared to jobber-length bits, making it well suited for production drilling and tight clearance work.

This Series R40 bit is rated for right-hand spiral flute cutting and is listed with titanium as the primary workpiece material, though its general-purpose grade suits a wide range of metals and hard plastics encountered in mechanical, HVAC, plumbing, and electrical trade work. Screw machine length bits are a common choice when drill press or hand-drill rigidity is needed in confined spaces or when drilling through structural components, enclosure panels, and fittings. The 2.5xD flute-to-diameter ratio supports chip evacuation at typical feed and speed rates for HSS tooling.

Key Features

• 29/64 inch (0.4531 inch) diameter with a 118-degree standard point angle for accurate starting
• Web-thinned tapered web reduces feed force and minimizes heat buildup at the cutting edge
• High speed steel construction provides toughness across a range of metals and hard plastics
• Screw machine (stub) length at 3-9/16 inches overall for increased rigidity over jobber bits
• Straight-cylindrical shank fits standard 3-jaw drill chucks without adapters
• Right-hand spiral flute geometry promotes consistent chip removal during through-hole drilling
• Meets ANSI standards for dimensional accuracy and performance consistency

Compatibility

Designed as a general-purpose screw machine length drill bit suitable for use in standard drill presses, hand drills, and CNC drilling fixtures accepting a straight-cylindrical shank in the 29/64 inch diameter range.

Installation Notes

Installation and use should follow standard machining safety practices — secure the workpiece before drilling and verify chuck grip on the shank before applying feed pressure. Ensure the drill press or power tool is de-energized before changing bits. Use appropriate cutting fluid or coolant for the workpiece material when drilling harder metals to extend tool life; this bit does not have a coolant-through design. Follow applicable shop safety codes and PPE requirements for eye and hand protection during all drilling operations.