Precision Twist Drill 5995839 Cobalt Extension Drill 3/16 in

Product Description

The PRECISION TWIST DRILL 5995839 is a cobalt aircraft extension drill bit designed for drilling in hard metals, stainless steel, and other high-strength materials where standard HSS bits lose their edge. The 3/16 inch diameter bit features a 135-degree split point that self-centers on contact, reducing the need for a center punch and minimizing walking on curved or angled surfaces. With a 2-5/16 inch flute length and an overall length of 6 inches, this bit reaches into recessed locations that standard-length drills cannot access. The straw finish indicates a heat treatment applied during manufacture. It is part of the CO500-6 series and conforms to NAS 907 Type J standards.

This drill bit is suited for aerospace, structural, and industrial fabrication applications where cobalt tooling is required to handle work-hardening alloys and high-heat conditions. The extended 6-inch overall length makes it practical for aircraft sheet metal work, deep-hole drilling in fixtures, and any job where clearance depth is a limiting factor. It is appropriate for use in drill presses, hand drills, and CNC setups running at speeds appropriate for cobalt tooling in the target material.

Key Features

• Cobalt construction resists heat buildup in hard and work-hardening metals
• 135-degree split point is self-centering and reduces thrust required to start the hole
• 6-inch overall length provides extended reach for recessed or deep drilling applications
• Straight-cylindrical shank fits standard 3-jaw chucks without adapters
• Right-hand spiral flute with web-thinned, tapered web configuration for efficient chip evacuation
• Conforms to NAS 907 Type J standards for aircraft-grade drilling applications

Compatibility

Designed as a general-purpose cobalt extension drill bit conforming to NAS 907 Type J, suitable for use in standard drill presses, hand drills, and CNC spindles accepting a 3/16 inch straight-cylindrical shank.

Installation Notes

This drill bit is installed and used by machinists, aircraft maintenance technicians, and industrial fabricators. Secure the shank fully in the chuck before operation and verify runout is within acceptable limits for the application. Use cutting fluid appropriate for the workpiece material to extend tool life and manage heat. Operate at speeds and feeds matched to the material being drilled — cobalt bits tolerate higher heat than HSS but still require proper speed selection to prevent premature wear.