Precision Twist Drill 5999978 Extra Length Drill Bit

Product Description

The PRECISION TWIST DRILL 5999978 is a high-speed steel extra length drill bit designed for deep-hole drilling applications where standard-length bits cannot reach. At 0.2812 inches in diameter with a 12-inch overall length and a 9-inch spiral flute, this bit delivers the reach needed for extended boring operations. The 118-degree standard point angle and web-thinned tip reduce thrust requirements and improve cutting efficiency. The straight-cylindrical shank fits conventional drill chucks without adapters. This bit is designed for machinists, tool-and-die trades, and maintenance professionals working on fabrication, assembly, and repair operations.

The 5999978 is suited for both production and job-shop environments requiring extended reach in drilling aluminum, magnesium, copper, nickel, titanium, synthetic materials, stainless steel, steel, hardened steel, nickel alloys, malleable iron, high-strength bronze, magnesium alloys, and reinforced plastics. The Series 1290 design targets general-purpose applications where a 12xD flute-to-diameter ratio is needed to clear chips effectively over the full depth of cut.

Key Features

• 12-inch overall length provides extended reach for deep-hole drilling
• 9-inch spiral flute length with regular helix promotes consistent chip evacuation
• 118-degree standard point angle with web-thinned, tapered web for reduced entry thrust
• High-speed steel construction, uncoated, for use across a wide range of workpiece materials
• Straight-cylindrical shank fits standard drill chucks directly
• Right-hand cutting direction, 2-flute configuration, ANSI-compliant Series 1290

Compatibility

Designed as a general-purpose extra length drill bit compatible with standard drill chucks and drill press or hand-drill setups accepting a 0.2812-inch straight-cylindrical shank. Primary workpiece materials include aluminum, magnesium, copper, nickel, titanium, and synthetic materials; secondary workpiece materials include hardened steel, stainless steel, nickel alloys, malleable iron, high-strength bronze, and reinforced plastics.

Installation Notes

Installation and use should be performed by qualified machinists or trade professionals familiar with drilling equipment and speeds appropriate for the selected workpiece material. Secure the shank fully in the chuck and verify runout before beginning a cut. Always power down and lock out the drill press or driving tool before changing bits. Do not exceed the rated speed range for the workpiece material, and use appropriate cutting fluid where required by the material being drilled.