Chicago-Latrobe 40568 135° NAS aircraft extension drill 5/32 in 28° split point HSS black oxide

135° NAS Aircraft Extension Drill

The Chicago-Latrobe 40568 is a high-speed steel drill bit with a 135-degree split point and black oxide finish. It is built for deep-hole drilling in aerospace and precision metalworking applications. The 28-degree helix angle supports chip evacuation in extended reach tasks. This tool suits professionals needing accurate hole placement in tough alloys.

Suited for deep-hole precision work

Machinists and maintenance technicians drilling deep, accurate holes in high-performance alloys will benefit from the split-point geometry and extended length. The design reduces walk and improves centering on curved or angled surfaces. Buyers needing standard jobber-length bits or carbide-tipped tooling for abrasive composites should consider other options. This bit is optimised for specific NAS-type requirements.

5/32 inch fractional size decides fit

The 5/32 inch diameter determines compatibility with fastener callouts and fixture bushings in aircraft assembly. The 4xD maximum drilling depth of 5/8 inch sets the practical limit for through-hole or blind-hole operations. Verify the exact fractional size and depth requirement against your engineering drawing before purchase. No other dimension in the data overrides this specification.