Precision Twist Drill 5996151 Cobalt Aircraft Extension Drill

Product Description

The PRECISION TWIST DRILL 5996151 is a cobalt aircraft extension drill bit designed for drilling in hard metals and high-temperature alloys where standard high-speed steel bits fall short. Built to Series CO501-6 standards and rated to NAS 907 Type J, this bit features a 135-degree split point for self-centering entry without a center punch, reducing walking and improving hole accuracy. The straight cylindrical shank measures 0.18 inches in diameter and accepts standard drill chucks. A straw finish indicates the cobalt content and heat treatment applied during manufacture. This bit is sized to wire gauge 15, with a decimal diameter of 0.180 inches, and is installed by machinists, aircraft maintenance technicians, and industrial tradespeople working on structural or precision drilling applications.

The 5996151 is suited for aircraft maintenance, general industrial fabrication, and structural metalworking where extended reach and cobalt hardness are required. The 6-inch overall length provides the additional clearance needed to reach recessed or deep-set hole locations that standard-length bits cannot access. Its right-hand cutting direction and two-flute spiral design provide efficient chip evacuation in ferrous and non-ferrous metals. The 2.1875-inch flute length supports a 4xD depth-to-diameter ratio, making it appropriate for moderate-depth holes in aerospace-grade and general-purpose metal stock.

Key Features

• 135-degree split point with self-centering geometry reduces drill walking on hard or curved surfaces
• Cobalt tool material resists heat and wear when drilling stainless steel, titanium, and high-temperature alloys
• 6-inch overall length provides extended reach for recessed or obstructed drilling locations
• NAS 907 Type J compliant for aircraft and aerospace maintenance applications
• Straw finish coating indicates cobalt heat treatment and provides mild corrosion resistance
• Web-thinned tapered web reduces thrust force and improves cutting efficiency

Compatibility

Designed as a general-purpose cobalt extension drill bit compatible with standard drill chucks accepting a 0.180-inch straight cylindrical shank. Suitable for use in hand drills, drill presses, and magnetic base drills configured for right-hand cutting bits.

Installation Notes

This bit is typically installed and used by machinists, aircraft maintenance technicians, and industrial tradespeople. Secure the straight shank firmly in a properly sized chuck before operation and confirm the workpiece is clamped or fixtured to prevent movement. Use appropriate cutting fluid or lubricant when drilling stainless steel or other hard alloys to extend bit life and reduce heat buildup. Allow the bit to cool between extended drilling operations to prevent premature wear to the cobalt cutting edges.