Precision Twist Drill 5998166 Jobber Drill Bit 27/64 in

Product Description

The PRECISION TWIST DRILL 5998166 is a jobber length drill bit designed for general-purpose drilling in a wide range of metallic materials. Built from high speed steel with a steam oxide coating, it runs a 135-degree split point that reduces walking on entry and lowers the thrust needed to start a hole. The straight cylindrical shank measures 0.4219 inches in diameter, matching the 27/64-inch cutting diameter, and the overall length is 5.375 inches. Two spiral flutes with a regular helix evacuate chips efficiently during through-hole and blind-hole operations. Web thinning is applied at the tip to further ease penetration in harder stock.

This bit is suited to metalworking, maintenance, and fabrication applications where steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium are being drilled. The R10B series designation indicates a heavy-duty jobber length format that meets ANSI and NAS 907 standards, making it appropriate for shop floor use, field maintenance, and production drilling where consistent hole quality is required. Machinists, tool-and-die workers, pipefitters, and HVAC fabricators commonly use bits of this type when drilling through structural members, fittings, or equipment housings.

Key Features

• 27/64 inch (0.4219 inch) cutting diameter with matching straight cylindrical shank for secure chuck retention
• 135-degree split point reduces walking and lowers entry thrust on hard materials
• Steam oxide coating provides mild lubricity and corrosion resistance during storage and use
• Web-thinned, tapered web construction reduces cutting resistance and heat buildup
• 3.9375-inch flute length allows drilling to a maximum depth of 3.9375 inches
• NAS 907 and ANSI standards compliance for consistent dimensional and performance tolerances

Compatibility

Designed for use in standard 3-jaw drill chucks accepting straight cylindrical shanks; suitable for drilling steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium per the R10B-R15B-R18B series application ratings.

Installation Notes

Install in a drill press, hand drill, or milling machine chuck rated for the shank diameter before energizing the spindle. Secure the workpiece firmly before drilling and use cutting fluid appropriate for the workpiece material, particularly when drilling stainless steel, superalloys, or titanium. Inspect the cutting edges and web for wear or chipping before each use; a dull bit generates excess heat and can work-harden stainless or titanium stock. Follow applicable shop safety practices and machine guarding requirements when operating rotating tooling.