IRWIN 31520 5/16-Inch Left-Hand M42 Cobalt Drill Bit
IRWIN 31520 is a left-hand drill for counterclockwise cutting, with a 5/16-inch diameter and shorter 3-3/4-inch overall length. Its M42 cobalt HSS construction and straight shank distinguish the material and connection, while the left-hand direction is the key check for broken-fastener drilling work.
Specifications and included details
- 5/16-inch cutting diameter; 3-3/4-inch overall and 2-1/8-inch flute lengths.
- Left-hand cutting direction for counterclockwise drilling.
- M42 high-speed steel with 8% cobalt and a gold oxide finish.
- 135-degree split point and straight shank.
Before ordering
Verify reverse-rotation operation on your drill and the diameter required for the fastener or extractor process. A left-hand bit can participate in removal work but cannot guarantee a seized fastener will unscrew. Match any extractor to its specified pilot diameter rather than assuming every 5/16-inch drilled hole fits it.
Product questions and answers
Does this drill cut clockwise?
No. It is explicitly left-hand and is intended for counterclockwise cutting. Confirm your drill can operate in the required direction.
Will it always remove a broken bolt without an extractor?
No. Removal depends on the fastener condition and application. This is a drill bit, not a guaranteed extraction system.
Is 3-3/4 inches a drilling-depth rating?
No. It is overall length. The listed flute length is 2-1/8 inches, and actual usable depth also depends on the setup.
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