Precision Twist Drill 5999381 Screw Machine Drill Bit

Product Description

The PRECISION TWIST DRILL 5999381 is a screw machine length drill bit engineered for high-performance material removal in demanding shop and field applications. Ground from high speed steel with a coated finish, it carries a 135-degree split point that reduces walking and lowers thrust during entry. The web-thinned, tapered web construction keeps cutting forces low while maintaining rigidity. At 0.277 inches in diameter — Letter size J — and an overall length of 2-11/16 inches, this stub-length bit fits tight-clearance fixtures and short-stroke drill presses where standard-length bits would be impractical. Licensed machinists, tool-and-die techs, and maintenance professionals reach for this geometry when precision and cycle time both matter.

The 5999381 is built to the R42C series specification, meeting ANSI and NAS 907 standards. It is rated for titanium as the primary workpiece material, placing it squarely in aerospace, defense, and industrial MRO environments where titanium fastener holes and structural components are common. The 1-1/2 inch flute length and 2.5xD flute-to-diameter ratio deliver effective chip evacuation in short-depth bores. Right-hand spiral flutes move chips away from the cut zone consistently. The straight-cylindrical shank seats cleanly in standard Jacobs-style chucks and collet holders without modification.

Key Features

• 135-degree split point reduces thrust and eliminates center-punch marking on most materials
• Web-thinned, tapered web construction lowers cutting resistance for high-performance drilling
• High speed steel body with coated finish for improved wear resistance and heat management
• Screw machine (stub) length fits tight-clearance fixtures and short-stroke machines
• Meets ANSI and NAS 907 standards — suitable for aerospace and defense work
• Straight-cylindrical shank compatible with standard chucks and collet holders

Compatibility

Designed as an OEM-style replacement or direct-use screw machine drill bit for applications requiring a 0.277 inch (Letter J) diameter stub-length bit in standard Jacobs-style chucks, collet systems, or drill press spindles accepting straight-cylindrical shanks.

Installation Notes

Installation and use should be performed by qualified machinists or maintenance technicians familiar with rotating cutting tools. Secure the shank fully in the chuck or collet and verify runout before engaging the workpiece. Always set spindle speed and feed rate appropriate to the workpiece material — titanium in particular requires lower surface footage and consistent coolant or lubricant flow to prevent work hardening. Inspect the cutting edges for chipping or wear before each use and replace the bit if edge integrity is compromised.