Cleveland C15991 Cobalt Jobber Drill Bit 29/64 in 135 Deg

Product Description

The CLEVELAND C15991 is a cobalt jobber-length drill bit designed for drilling into superalloys, stainless steel, and other hard, heat-resistant materials. Built to Series 3780 specifications and graded M42 heavy duty cobalt steel, this bit holds an edge longer than standard HSS tooling when cutting tough workpiece materials. The 135-degree split point reduces walking and lowers feed force at entry. A fast spiral flute configuration promotes chip evacuation, and the oxide coating provides additional surface hardness and heat resistance. Overall length is 5-5/8 inches with a 2-1/8 inch flute length. This bit conforms to ASME B94.11M standards and carries a NAS specification designation.

The C15991 is suited for production and maintenance drilling applications where workpiece materials exceed the performance limits of standard high-speed steel bits. Common applications include aerospace fabrication, industrial maintenance, and mechanical contracting work involving superalloy fastener holes, structural members, or hard stainless components. The straight-cylindrical shank accepts standard three-jaw drill chucks found on benchtop drill presses, magnetic drills, and hand-held power drills. Right-hand cut with a fast spiral and tapered web configuration makes it effective in both handheld and fixed drilling setups.

Key Features

• M42 cobalt steel construction for extended tool life in superalloy and hard material drilling
• 135-degree split point reduces drill walking and entry feed pressure
• Fast spiral flute promotes chip clearance during deep hole drilling
• Oxide coating adds surface hardness and thermal resistance
• Web-thinned, tapered web configuration lowers cutting resistance
• Conforms to ASME B94.11M and NAS specification designations

Compatibility

Designed as an OEM-style replacement or direct equivalent for jobber-length cobalt drill bits in the 0.4000 to 0.5000 inch diameter range. Fits any standard three-jaw drill chuck accepting a straight-cylindrical shank at 29/64 inch diameter.

Installation Notes

Installation of this drill bit is performed by machinists, tool-and-die tradespeople, and industrial maintenance technicians. Secure the straight-cylindrical shank fully in a properly sized drill chuck before operation and verify chuck key is removed before powering the machine. When drilling superalloys, use appropriate cutting fluid to manage heat buildup and extend bit life. Inspect the cutting edges and split point for wear before each use; a dull cobalt bit in hard material increases heat and can lead to work hardening of the workpiece.