Precision Twist Drill 6001438 Letter X Hss Extension Drill

Product Description

The PRECISION TWIST DRILL 6001438 is a Letter X aircraft extension drill bit designed for deep-hole drilling applications in metalworking and aerospace-adjacent maintenance work. Built from high speed steel (HSS) with an oxide finish, this bit measures 0.397 inches in diameter and features a 135-degree split point that is self-centering, eliminating the need for a center punch on most surfaces. The 12-inch overall length and 3.75-inch spiral flute provide the reach needed to access recessed or hard-to-reach bore locations. Licensed trades and skilled machinists install this type of tooling in drill presses, magnetic base drills, and extended-reach hand drill setups.

This drill bit is suited for general-purpose metal drilling in aircraft structural maintenance, fabrication shops, and industrial production environments where standard-length bits cannot reach the workpiece. The straight-cylindrical shank accepts standard drill chucks without adapters. Its right-hand cutting direction, two-flute spiral geometry, and web-thinned tapered web promote efficient chip evacuation in deep-hole conditions. The 4xD flute-length-to-diameter ratio supports stable cutting in steel, aluminum, and similar materials at appropriate feed and speed rates.

Key Features

• 135-degree split point with self-centering geometry reduces walking and eliminates center-punching on most metals
• 12-inch overall length provides extended reach for deep or obstructed bore locations
• High speed steel construction with oxide finish for corrosion resistance and reduced friction
• Web-thinned tapered web improves chip flow and reduces thrust in deep-hole drilling
• Straight-cylindrical shank at 0.397 inches fits standard drill chucks without adapters
• Meets NAS 907 Type B standard for aircraft-quality drill tooling

Compatibility

Designed as a general-purpose aircraft extension drill bit conforming to NAS 907 Type B, compatible with standard drill chucks accepting a 0.397-inch straight-cylindrical shank in drill presses, hand drills, and magnetic base drill setups.

Installation Notes

This tooling is typically installed and operated by machinists, aircraft maintenance technicians, or industrial tradespeople familiar with metal drilling procedures. Secure the shank fully in the drill chuck and verify concentricity before starting a cut. Always use appropriate cutting fluid for the workpiece material to prolong tool life and maintain hole quality. Follow shop safety protocols including eye protection and securing the workpiece before drilling.