Chicago-Latrobe 11143 #19 135° NAS Aircraft Extension Drill

Aircraft Extension Drill #19

The Chicago-Latrobe 11143 is a NAS-type aircraft extension drill sized for #19 wire gauge holes. It is built for aerospace maintenance and manufacturing tasks that demand precise, deep-hole drilling in tough alloys. The 135-degree split point reduces walking on hard surfaces and starts the cut cleanly without a centre punch.

Sustained drilling behaviour

High-speed steel with a black oxide finish resists heat build-up during extended drilling cycles in high-performance machining grades. The 28-degree helix angle clears chips efficiently from the 2 1/8 in maximum drilling depth, preventing packing that would otherwise stall the cut. A 4xD length-to-diameter ratio provides reach without excessive deflection under load.

Practical limits of the HSS interface

High-speed steel performs reliably in ferrous and non-ferrous aerospace materials but loses hardness faster than cobalt or carbide when temperatures exceed its tempering range. The black oxide coating aids lubricity yet does not substitute for proper cutting fluid in deep holes. Users needing longer tool life in abrasive composites or hardened steels should evaluate alternative substrate materials.