Hertel C.E06.0249 Aircraft Extension Drill Bit No. 40

Product Description

The HERTEL C.E06.0249 is a No. 40 wire-gauge aircraft extension drill bit engineered for precision drilling in aerospace and structural applications. Manufactured from cobalt high-speed steel, this bit delivers superior heat resistance and edge retention when working through hard metals, stainless steel, and high-strength alloys. The 135-degree split point promotes self-centering on entry, reducing walking and the need for a center punch. A straw finish indicates controlled heat treatment during manufacture. At 6 inches overall length, this extended-reach bit gives technicians access to confined or deep-bore locations that standard-length bits cannot reach. Licensed electricians, aircraft maintenance technicians, and metalworking tradespeople are the primary installers.

This bit is suited for drilling thin sheet metal, aircraft skin, structural brackets, and similar assemblies where a No. 40 diameter of 0.0980 inches is specified. The 1.375-inch spiral flute efficiently evacuates chips during through-hole drilling in both horizontal and vertical orientations. The straight cylindrical shank seats directly into standard drill chucks without reduction sleeves. Right-hand cutting direction is compatible with conventional drill presses, hand drills, and pneumatic tools common to aircraft maintenance and fabrication shops. General-purpose tool performance rating makes this bit appropriate for production and maintenance work across a broad range of base metals.

Key Features

• Cobalt construction provides elevated heat resistance and extended tool life in hard and abrasive metals
• 135-degree split point with self-centering geometry reduces walking on entry and eliminates center-punch steps
• Web-thinned, tapered web configuration reduces cutting torque and improves chip flow
• 6-inch overall length extends reach into confined spaces, deep cavities, and recessed structural members
• Straw finish indicates controlled tempering to preserve cobalt hardness
• Meets NAS 907 standard for aircraft extension drill bits

Compatibility

Designed as an OEM-style aircraft extension drill bit for use in applications requiring a No. 40 wire-gauge diameter and conformance to NAS 907 standards. Fits standard straight-cylindrical drill chucks sized for a 0.0980-inch shank diameter.

Installation Notes

Installation is performed by qualified machinists, aircraft maintenance technicians, or metalworkers using a compatible drill press, hand drill, or pneumatic drill motor. Ensure the workpiece is securely clamped before drilling to prevent rotation and bit breakage. Use appropriate cutting fluid or lubricant when drilling hard alloys to extend bit life and maintain dimensional accuracy. Inspect the cutting edges before each use and replace bits that show chipping, heat discoloration beyond the straw band, or measurable diameter wear.