Precision Twist Drill 5999406 Screw Machine Drill Bit

Product Description

The PRECISION TWIST DRILL 5999406 is a screw machine length drill bit designed for high-performance metal cutting in demanding production and maintenance applications. Built from high speed steel with a coated finish, this bit features a 135-degree split point and web-thinned, tapered web construction that reduces walking and lowers thrust force on entry. It measures 0.25 inches in diameter with an overall length of 2.5 inches and a flute length of 1.375 inches. The straight-cylindrical shank fits standard drill chucks and quick-change systems. Licensed machinists, HVAC technicians, plumbers, and electricians reach for stub-length bits like this when working in tight clearances where a jobber-length bit would flex or bind.

The Series R40C R40C configuration is rated for heavy-duty drilling with a flute-to-diameter ratio of 2.5xD, making it well suited for ferrous metals, titanium, and other hard workpiece materials. The screw machine length body reduces overhang for improved rigidity and hole accuracy. This bit is commonly used in sheet metal fabrication, mechanical room rough-ins, equipment repair, and production drilling where a short, stiff bit is preferred over a standard jobber length. It conforms to ANSI and NAS 907 specifications, confirming dimensional consistency across interchangeable tooling setups.

Key Features

• 135-degree split point reduces thrust and prevents wandering on entry
• Web-thinned, tapered web lowers cutting resistance in hard materials
• High speed steel with coated finish for extended tool life
• Screw machine (stub) length provides rigidity in confined spaces
• Right-hand spiral flute clears chips efficiently during through-hole drilling
• Meets ANSI and NAS 907 dimensional standards

Compatibility

Designed as an OEM-style screw machine length drill bit compatible with standard straight-cylindrical shank drill chucks and quick-change holders. Primary workpiece material rating includes titanium and ferrous metals per Series R40C specifications. Drill bit size E (0.2500 inches decimal) fits within the 0.2500 to 0.3000 inch size range of this series.

Installation Notes

Install this bit in a properly sized chuck and verify the shank is fully seated and secured before operation. Power down and de-energize or lock out any equipment before drilling into live assemblies or panels, following applicable OSHA lockout/tagout procedures. Use appropriate cutting fluid or coolant when drilling titanium or hard ferrous metals to preserve tool life and maintain dimensional accuracy. Inspect the cutting edges and split point for wear before each use and replace the bit if chipping or dulling is observed.