Precision Twist Drill 5995507 Cobalt Extension Drill Bit

Product Description

The PRECISION TWIST DRILL 5995507 is a cobalt aircraft extension drill bit designed for drilling in tough materials including hardened steels, stainless steel, and high-temperature alloys. Built to NAS 907 Type J standards, this bit features a 135-degree split point that is self-centering, reducing the need for a center punch and minimizing walking on entry. The straw finish indicates heat treatment consistent with cobalt tooling. With a wire gauge size of No. 8 and a decimal diameter of 0.199 inches, it delivers precise hole sizing for aerospace-style and general metalworking applications. Licensed tradespeople and machinists in HVAC, fabrication, and maintenance fields rely on this bit for accurate, repeatable results in demanding materials.

This drill bit suits applications requiring extended reach beyond what a standard-length bit provides. The 2.4375-inch flute length and 6-inch overall length make it appropriate for drilling through thicker workpieces or in confined areas where standard jobber bits cannot reach. The straight-cylindrical shank at 0.199 inches diameter fits standard drill chucks without adapters. General-purpose performance covers structural steel, sheet metal stacks, and similar substrates common in commercial HVAC installation, electrical rough-in, and plumbing rough-in work.

Key Features

• 135-degree split point is self-centering for accurate hole starts without center punching
• Cobalt construction with straw finish provides increased heat and wear resistance over standard HSS bits
• Extended 6-inch overall length allows drilling in deep or hard-to-reach locations
• Two-flute spiral design with web-thinned, tapered web for efficient chip evacuation
• Right-hand cutting direction compatible with standard drill drivers and drill presses
• Meets NAS 907 Type J standard for aircraft-quality drill performance

Compatibility

Designed as a general-purpose cobalt extension drill bit compatible with any standard drill chuck accepting a 0.199-inch straight-cylindrical shank, suitable for use in handheld drills, drill presses, and magnetic base drills across metalworking and trade installation applications.

Installation Notes

A licensed machinist, journeyman tradesperson, or qualified technician should select proper speeds and feeds for the material being drilled when using cobalt bits. Secure the workpiece firmly before drilling and use cutting fluid or oil when drilling ferrous metals to extend tool life and improve hole finish. Inspect the bit for chipping or wear before each use. Never apply side loading to an extension drill, as the extended length increases leverage and the risk of breakage.