Chicago-Latrobe
Chicago-Latrobe 11155 #31 135° NAS Aircraft Extension Drill
A #31 high-speed steel drill with a 135-degree split point, black oxide finish and 1-5/8 inch maximum drilling depth
- 135° split point starts on contact for precise holes
- #31 wire-gauge size matches NAS aircraft specifications
- High-speed steel with black oxide resists wear in tough alloys
- 1-5/8 in drilling depth handles extended reach jobs
- 28° helix angle clears chips efficiently during deep drilling
NAS Aircraft Extension Drill
The Chicago-Latrobe 11155 is a #31 size drill bit built to NAS aircraft specifications. It targets aviation maintenance technicians and precision metalworkers who need accurate hole placement in thin sheet materials. The 135-degree split point reduces walking and ensures clean entry on hard surfaces.
High-Speed Steel Limits
High-speed steel construction with black oxide finish handles general machining at a 28-degree helix angle. The material suits wire and similar alloys but wears faster than cobalt or carbide in abrasive or high-temperature drilling. Maximum drilling depth reaches 1 5/8 inches, restricting use to shallow-hole applications.
Straightforward Chuck Fit
The straight shank fits standard drill chucks without adapters, so setup is quick on portable or bench machines. The split point self-centres, yet the long extension can deflect if side pressure is applied or if the workpiece is not rigidly clamped. Clear chips frequently to avoid binding at depth.
Highlights
- 135° split point starts on contact for precise holes
- #31 wire-gauge size matches NAS aircraft specifications
- High-speed steel with black oxide resists wear in tough alloys
- 1-5/8 in drilling depth handles extended reach jobs
- 28° helix angle clears chips efficiently during deep drilling
Specifications
| Brand | CHICAGO-LATROBE |
|---|
Questions about this item
Which drill bit size should I choose for my application?
The #31 size is a specific wire-gauge diameter; select it when your engineering drawing or fastener chart calls for a #31 hole.
What does the 135-degree point angle do once the bit is in the machine?
A 135-degree split point centres faster and reduces thrust on hard materials compared with shallower angles.
What does the 28-degree helix angle cap in practice?
The 28-degree helix controls chip evacuation rate and limits how aggressively the bit pulls into the workpiece.
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