Chicago-Latrobe
Chicago-Latrobe 11166 Aircraft Extension Drill 135 Degree #42 HSS Black Oxide
A #42 HSS aircraft extension drill with a 135-degree split point and black oxide finish for deep-hole drilling
- 135-degree split point starts on contact without wandering
- #42 wire-gauge drill bit targets precise small-hole applications
- 1-1/4 inch maximum drilling depth reaches through extended workpieces
- High-speed steel with black oxide resists wear and reduces chip welding
- 28-degree helix angle clears chips efficiently in deep holes
Aircraft Extension Drill #42
The Chicago-Latrobe 11166 is a high-speed steel drill bit with a 135-degree split point and black oxide finish. It is engineered for aircraft maintenance and precision metalworking tasks where accurate hole placement and reduced thrust are required. The 4xD design suits deep-hole applications in tough alloys. Machinists and aviation technicians gain reliable performance in demanding materials.
Upgrade From Standard Jobber Bits
This drill replaces general-purpose jobber-length bits when maximum drilling depth reaches 1 1/4 in and workpiece access demands extra length. The jump is worth it for NAS-type specifications requiring a 135-degree split point that centres without a pilot hole. Standard bits lack the rigidity and point geometry for consistent results in high-strength steels at this depth. Buyers needing shorter flute lengths or softer-material optimisation should choose a different tool.
Straight Shank Fits Standard Chucks
Installation is straightforward: the straight shank secures in any compatible drill chuck or collet without adapters. The split point minimises walking, yet excessive feed pressure can still chip the cutting edges in hardened stock. Black oxide aids chip flow, but inadequate coolant leads to premature wear. Users must match speed and feed to the material grade to avoid breakage in deep holes.
Highlights
- 135-degree split point starts on contact without wandering
- #42 wire-gauge drill bit targets precise small-hole applications
- 1-1/4 inch maximum drilling depth reaches through extended workpieces
- High-speed steel with black oxide resists wear and reduces chip welding
- 28-degree helix angle clears chips efficiently in deep holes
Specifications
| Brand | CHICAGO-LATROBE |
|---|
Questions about this item
What chuck size fits the #42 aircraft extension drill?
The #42 drill bit has a wire-gauge shank that fits standard drill chucks accepting that diameter; the 135-degree split point engages material immediately without a centre punch.
How do I install the 11166 extension drill in a drill press or hand drill without run-out?
Insert the black-oxide shank fully into the chuck, tighten evenly on all three jaws, and verify the 135-degree point runs true before applying feed pressure.
When should the high-speed-steel bit be replaced or resharpened?
Replace or resharpen when the 135-degree split point dulls, the black-oxide coating wears off, or the 1-1/4-inch maximum drilling depth can no longer be reached cleanly.
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