Precision Twist Drill 6001290 Letter H Aircraft Drill Bit

Product Description

The PRECISION TWIST DRILL 6001290 is a Letter H aircraft extension drill bit designed for deep-reach drilling applications where standard-length bits fall short. Built from high speed steel with an oxide finish, this bit measures 6 inches in overall length with a 2.875-inch spiral flute. The 135-degree split point is self-centering and web-thinned, reducing the walking tendency and thrust required at entry. Shank diameter matches the drill diameter at 0.266 inches, allowing use in standard chucks. Right-hand cutting action and a tapered web configuration make this a dependable general-purpose bit for sheet metal and aerospace-style drilling work performed by machinists, aircraft maintenance technicians, and industrial tradespeople.

This drill bit is suited for applications requiring extended reach into recessed cavities, deep holes in structural assemblies, or stacked material. The aircraft extension format is common in airframe maintenance, fabrication shops, and industrial production environments where standard jobber-length bits cannot access the work. The 4xD flute-length-to-diameter ratio provides adequate chip clearance during through-hole drilling in metals. The two-flute spiral configuration supports efficient chip evacuation in ferrous and non-ferrous stock.

Key Features

• Letter H size: 0.266 inches diameter for precise fit to specification tolerances
• 135-degree split point with self-centering geometry eliminates the need for a center punch in most applications
• Web-thinned, tapered web construction reduces drill thrust and entry resistance
• 6-inch overall length with 2.875-inch flute provides extended reach over standard jobber bits
• High speed steel construction with oxide finish for corrosion resistance and reduced friction
• Meets NAS 907 Type B standards for aerospace and industrial use

Compatibility

Designed as a general-purpose aircraft extension drill bit compatible with standard 3-jaw chucks and drill motors accepting a 0.266-inch straight cylindrical shank. Conforms to NAS 907 Type B standards.

Installation Notes

This bit is installed and operated by machinists, aircraft maintenance technicians, and metal fabricators using handheld or bench-mounted drill equipment. Ensure the shank is fully seated and the chuck is tightened before operation. Use appropriate cutting fluid when drilling ferrous materials to extend tool life and improve hole finish. Inspect the cutting edges for wear or chipping before each use and do not exceed the recommended feed and speed ratings for the workpiece material.