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Black oxide aircraft extension drill bit with split point

Chicago-Latrobe

Chicago-Latrobe 40476 135 Degree NAS-Type Aircraft Extension Drill 9/32 in

SKU CH-DTVX-WGXH6

Aircraft extension drill with a 135-degree split point for reduced walking, made from high-speed steel with black oxide coating for durability

  • Product typeDrill Bits
  • Main materialHAWA
  • 135-degree split point starts holes cleanly without wandering
  • High-speed steel with black oxide resists wear and heat
  • 28-degree helix clears chips efficiently in deep holes
  • 4×D length reaches confined aircraft structures
  • NAS-type geometry meets aerospace drilling standards

135° NAS-Type Aircraft Extension Drill

This 9/32 inch fractional drill bit features a 135 degree split point designed for precision starts in aircraft-grade materials. The High Speed Steel body with black oxide finish targets machinists and maintenance crews who need reliable hole-making in tough alloys.

Thermals Noise and Power Draw

As a hand-tool accessory the bit generates no electrical noise and draws no power of its own; cutting heat is managed by the black oxide coating and proper feed rates during operation. The 28 degree helix angle aids chip evacuation to keep temperatures stable at depth.

Upgrade Path and Value

The design replaces standard jobber-length bits when extra reach is required, offering a 4xD drilling depth of 1 1/8 inch for deeper holes without changing tools. The jump is worth it for repetitive aerospace or structural work where split-point accuracy and extended length reduce cycle time.

How it compares

Measured against everything we stock in Bits, Hole Saws & Accessory Kits, at today’s prices. Recalculated every night.

Price $10.99
Cheaper than about 86% of the 5,493 comparable items (median $27.99).

Specifications

Product
Brand nameCHICAGO-LATROBE
Product typeDrill Bits
Size & build
Main materialHAWA

Questions about this item

How do I install the 40476 drill bit into my drill chuck, and what step do people get wrong?

Insert the straight shank fully into the chuck jaws and tighten securely; the common mistake is not seating the shank completely, which causes runout and premature wear.

What maintenance or replacement will the 40476 drill bit need later?

The high-speed steel cutting edges dull with use; resharpen the 135-degree split point to the original geometry or replace the bit when sharpening no longer restores cutting performance.

What limit appears first on the 40476 drill bit during sustained drilling?

The maximum drilling depth of 1 1/8 inches is reached before the 4xD length limit, stopping further penetration in a single pass.

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