Chicago-latrobe 11225 Letter F Aircraft Extension Drill Bit

Product Description

The CHICAGO-LATROBE 11225 is a Letter F aircraft extension drill bit designed for deep-reach drilling applications in metal, composites, and other materials common to aerospace and industrial work. Built from high speed steel with an oxide finish, it features a 135-degree split point that is self-centering, reducing the need for a center punch on most surfaces. The bit measures 0.257 inches in diameter with a 2.875-inch flute length and an overall length of 12 inches, making it well suited for accessing fastener locations that standard-length drills cannot reach. A two-flute spiral design with a web-thinned, tapered web configuration promotes efficient chip evacuation and consistent cutting performance.

This drill bit is used in aerospace maintenance, aircraft assembly, and general industrial fabrication where extended reach is required. The 12-inch overall length allows technicians to drill through deep structures, stacked panels, or confined areas without secondary extensions. It is equally applicable in general-purpose metal fabrication shops, MRO facilities, and production environments that require reliable, repeatable hole sizing to tight tolerances. Licensed aircraft mechanics, machinists, and industrial maintenance technicians are the primary installers of this type of tooling.

Key Features

• 135-degree split point is self-centering for accurate hole starting without a center punch
• High speed steel construction provides durability across a wide range of metals and composites
• Oxide finish helps reduce friction and improve chip flow during cutting
• 12-inch overall length delivers extended reach into deep or confined structures
• Web-thinned, tapered web reduces thrust required and improves cutting efficiency
• Meets NAS 907 Type B standards for aircraft-grade tooling

Compatibility

Designed as a general-purpose aircraft extension drill bit conforming to NAS 907 Type B, suitable for use in standard drill chucks and right-hand rotation drilling equipment accepting a 0.257-inch straight-cylindrical shank.

Installation Notes

Installation of this drill bit requires a compatible drill motor or press accepting a straight-cylindrical shank. Secure the shank fully in the chuck before operation and verify chuck tightness to prevent slippage under load. Use appropriate cutting fluid or coolant when drilling hard metals to extend tool life and maintain hole tolerance. Always wear eye protection and follow applicable shop safety procedures when operating rotary cutting tools.