Precision Twist Drill 5996131 Cobalt Aircraft Drill

Product Description

The PRECISION TWIST DRILL 5996131 is a cobalt aircraft extension drill designed for precision drilling in hard and tough materials where standard high-speed steel bits fall short. Built to Series CO501-6 specs, it features a 135-degree split point that is self-centering and eliminates the need for a center punch on most surfaces. The drill has a wire gauge size of 52, a decimal diameter of 0.0635 inches, and a 7/8-inch (0.8750 inches) flute length with a right-hand spiral flute configuration. The straw finish indicates heat treatment to cobalt tooling standards. Web thinning is applied to reduce thrust and improve chip evacuation.

This drill is suited for aerospace, aviation maintenance, and general metalworking applications where extended reach or tight-tolerance hole sizing is required. The straight-cylindrical shank fits standard drill chucks and collets used in both handheld and bench-mounted setups. Its 6-inch overall length provides extension capability beyond what a jobber-length bit offers. General-purpose cobalt construction makes it appropriate for stainless steel, high-nickel alloys, titanium, and hardened steels commonly encountered in aircraft and industrial fabrication work.

Key Features

• 135-degree split point is self-centering for accurate hole placement without a center punch
• Cobalt tool material resists heat buildup in hard metals and abrasive materials
• Straw finish provides surface hardness indication consistent with properly heat-treated cobalt tooling
• Web-thinned tapered web reduces cutting resistance and improves chip flow
• 6-inch overall length delivers extended reach for aircraft panel and structural drilling
• Meets NAS 907 Type J standard for aircraft extension drill geometry

Compatibility

Designed as an OEM-style replacement or direct-use cobalt aircraft extension drill conforming to NAS 907 Type J, Series CO501-6, suitable for applications requiring a wire gauge size 52 (0.0635 inches) diameter straight-shank drill with extended reach.

Installation Notes

Installation of this drill is performed by machinists, aircraft maintenance technicians, and metalworking professionals. Secure the straight-cylindrical shank fully in the drill chuck or collet before use, and verify runout is within acceptable limits for tight-tolerance work. Use appropriate cutting fluid or lubricant when drilling stainless steel, titanium, or hardened alloys to extend tool life and maintain hole quality. Follow applicable shop safety procedures and wear proper eye protection during drilling operations.