Cleveland C11639 Jobber Drill Bit Letter K 0.2810 in Hss

Product Description

The CLEVELAND C11639 is a jobber-length twist drill bit sized to letter K (0.2810 inches) and built from heavy-duty high speed steel with a bright, uncoated finish. The 135-degree split point reduces walking on entry and requires less thrust than a conventional 118-degree tip, making it well suited to production drilling and service-shop work alike. Overall length is 4.25 inches with a 2.875-inch flute length and a straight-cylindrical shank measuring 0.2810 inches in diameter. Two right-hand spiral flutes with a tapered, web-thinned web configuration clear chips efficiently and help maintain concentricity through the cut.

The C11639 is intended for drilling aluminum and similar non-ferrous materials, though the heavy-duty HSS construction handles general-purpose hole-making in a wide range of applications. Series 2222 jobber-length geometry fits standard drill chucks found on handheld drill motors, drill presses, and CNC machining centers. This bit is a single-piece package with a minimum order quantity of one, appropriate for maintenance technicians, tool cribs, and small-batch production setups that need a reliable letter-K drill on hand.

Key Features

• 135-degree split point reduces thrust and minimizes bit walking at entry
• Web-thinned, tapered web configuration improves chip evacuation and cutting efficiency
• Heavy-duty high speed steel construction for extended tool life in production use
• Bright uncoated finish — no coating buildup to affect dimensional tolerance
• Straight-cylindrical shank fits standard three-jaw chucks without adapters
• Meets NAS 907 Type B specification for consistent dimensional accuracy

Compatibility

Designed as a jobber-length replacement or stock drill bit for use in standard three-jaw chucks on handheld drill motors, drill presses, and CNC machining centers requiring a letter K (0.2810-inch) bore diameter.

Installation Notes

Install and tighten the shank in a properly sized drill chuck before applying power; never seat a drill bit in a running spindle. For drill press and CNC use, secure the workpiece with clamps or a vise — never hold aluminum stock by hand during drilling. Verify spindle speed is appropriate for the material and bit diameter before starting the cut. Inspect the cutting edges for wear or chipping before each use and replace the bit when diameter tolerance or point geometry is compromised.