Hertel C.E05.0253 Aircraft Extension Drill Bit No 39

Product Description

The HERTEL C.E05.0253 is a No. 39 wire-gauge aircraft extension drill bit engineered for precision drilling in tight-clearance and hard-to-reach applications. Built from high-speed steel with an oxide finish, this bit features a 135-degree split point for self-centering entry with minimal walking, eliminating the need for a center punch in most setups. The extended 12-inch overall length gives technicians the reach required for deep structural assemblies, while the 1.375-inch spiral flute efficiently clears chips during the cut. It is sized at 0.0995 inch decimal diameter and is suited for use in production and MRO drilling environments.

This aircraft extension drill bit is used in aerospace, aviation maintenance, and sheet-metal fabrication where standard-length bits cannot reach fastener locations. The extended reach is particularly valuable when drilling through stacked panels, framing members, or structural ribs. General-purpose tool performance makes it equally practical in automotive bodywork, HVAC ductwork fabrication, and electrical conduit installation where deep-reach drilling is required. Installation is typically performed by aviation maintenance technicians, sheet-metal mechanics, or journeymen working under applicable maintenance and fabrication standards.

Key Features

• 135-degree split point with web thinning for self-centering, reduced thrust, and clean entry
• 12-inch overall length provides extended reach into deep or obstructed workspaces
• High-speed steel construction offers durability across a broad range of materials
• Oxide finish improves lubricity and provides basic corrosion resistance during storage and use
• Straight-cylindrical shank at 0.0995 inch diameter fits standard drill chucks without adapters
• Right-hand spiral flute with tapered web configuration for efficient chip evacuation
• Meets NAS 907 standard for aircraft extension drill bits

Compatibility

Designed as an OEM-style replacement or direct-use aircraft extension drill bit for applications requiring a No. 39 wire-gauge bit with a straight-cylindrical shank, conforming to NAS 907.

Installation Notes

This bit should be installed in a drill motor or press equipped with a chuck sized for a 0.0995-inch straight shank. Secure the shank fully before operation to prevent slippage during extended-reach drilling. Use appropriate cutting fluid when drilling ferrous materials to extend bit life and maintain dimensional accuracy. Inspect the cutting edges and web area before each use and replace the bit if chipping or excessive wear is observed.