Precision Twist Drill 5999775 Cobalt Jobber Drill Bit

Product Description

The PRECISION TWIST DRILL 5999775 is a cobalt jobber-length drill bit designed for demanding metal drilling applications. Built from high-speed steel with a cobalt formulation and finished with a bronze oxide coating, this bit handles hard materials where standard HSS bits fall short. It carries a No. 10 wire gauge size, equivalent to 0.1935 inches in diameter, and features a 135-degree split point that reduces walking and improves bite on curved or hardened surfaces. The straight-cylindrical shank provides a secure grip in standard three-jaw chucks. This is a production and maintenance tool intended for use by machinists, millwrights, and skilled tradespeople working in metal fabrication and repair environments.

This bit is suited for drilling steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium. The 135-degree point geometry and web-thinned tip make it a practical choice when working with tough or gummy alloys that tend to work-harden under cutting pressure. A regular spiral flute with a 6xD flute-to-diameter ratio clears chips efficiently during through-hole and moderate-depth drilling operations. It conforms to NAS 907 specification, placing it within defined dimensional and material standards for jobber drill bits used in aerospace and industrial settings.

Key Features

• No. 10 wire size (0.1935 inches diameter) with matching straight-cylindrical shank diameter
• 135-degree standard split point reduces drill walking and improves penetration on hard surfaces
• High-speed steel with cobalt formulation for extended tool life in ferrous and exotic alloys
• Bronze oxide coating provides lubricity and mild corrosion resistance during storage and use
• Web-thinned, tapered web construction reduces thrust force and heat buildup
• NAS 907 compliant — meets aerospace and industrial dimensional standards

Compatibility

Designed for general-purpose drilling in steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium. Compatible with any standard drill press, hand drill, or CNC spindle accepting a 0.1935-inch straight-cylindrical shank. Belongs to Series R88CO-R89CO.

Installation Notes

Install this bit into a properly sized chuck and verify the shank is fully seated before use. Always power down and lock out any machine before changing bits. Drilling cobalt-grade bits into hard or work-hardening alloys benefits from low RPM and consistent feed pressure to avoid overheating the cutting edge. Use appropriate cutting fluid for stainless steel, titanium, and superalloy applications to extend bit life and maintain dimensional accuracy.