Cleveland C70188 Cobalt Jobber Drill Bit Size 55

Product Description

The CLEVELAND C70188 is a cobalt jobber length drill bit designed for precision drilling in metal fabrication and maintenance applications. Manufactured from M42 cobalt high-speed steel with a gold oxide coating, this bit delivers extended tool life when working with hard or abrasive materials. It carries a 135-degree split point for fast starts without center-punching and a web-thinned, tapered web configuration that reduces thrust. The straight-cylindrical shank measures 0.0520 inches in diameter, matching the wire gauge No. 55 drill size. Licensed HVAC, plumbing, and electrical technicians frequently reach for this size when drilling small-diameter pilot holes in sheet metal enclosures, brackets, and equipment panels.

The C70188 is suited for drilling aluminum as its primary workpiece material, making it a practical choice for light-gauge sheet metal work, HVAC duct hardware, electrical panel fabrication, and plumbing fixture rough-in. The two-flute spiral design with regular spiral type clears chips efficiently in through-hole drilling. The 1-7/8 inch overall length fits standard drill chucks and close-quarters drill guides common in service work. Conformance to NAS 907 Type J ensures the bit meets aerospace and industrial dimensional standards, making it appropriate for precision trade applications where hole tolerance matters.

Key Features

• M42 cobalt steel construction for heat and wear resistance during metal drilling
• Gold oxide coating reduces friction and extends cutting life
• 135-degree split point starts on contact without center-punching
• Web-thinned tapered web reduces drilling thrust and feed force
• Two-flute regular spiral flute design for efficient chip evacuation
• Meets NAS 907 Type J dimensional standard for consistent hole tolerance

Compatibility

Designed as an OEM-style jobber length drill bit in wire gauge size No. 55 with a straight-cylindrical shank, compatible with standard keyed and keyless drill chucks accepting shank diameters of 0.0520 inches.

Installation Notes

Use with a variable-speed drill press or hand drill set to an appropriate low-to-moderate speed for cobalt bits in metal stock. Always secure the workpiece before drilling to prevent bit walking or breakage at this small diameter. Cutting fluid or light oil is recommended when drilling aluminum or steel to preserve coating life and maintain hole tolerance. Dispose of worn bits per shop safety protocols and inspect for tip damage before each use.