Precision Twist Drill 5998986 Drill Bit Letter Z Hss

Product Description

The PRECISION TWIST DRILL 5998986 is a jobber-length drill bit sized to letter Z (0.4130 inches decimal equivalent), designed for general-purpose drilling in a wide range of materials. Manufactured from high-speed steel with a steam oxide coating, it features a 135-degree split point with web thinning for reduced thrust and faster starts on tough workpieces. The spiral flute geometry and tapered web construction promote efficient chip evacuation during through-hole drilling. This bit is used by machinists, maintenance technicians, and metalworking professionals in production and job-shop environments.

This drill bit is suited for drilling steel, stainless steel, cast iron, non-ferrous metals, superalloys, titanium, and other hard materials. The 135-degree point angle makes it particularly effective on harder workpiece materials where a standard 118-degree point would walk or require excessive feed force. The Series R10B-R15B-R18B designation places it in PRECISION TWIST DRILL's heavy-duty general-purpose product line, built to ANSI and NAS 907 standards. Typical applications include structural drilling, maintenance repair, and production hole-making on manual and CNC drill presses.

Key Features

• Letter Z size — 0.4130 inch decimal equivalent for precise hole sizing
• 135-degree split point with web thinning reduces thrust and self-centers on entry
• High-speed steel construction with steam oxide coating for lubricity and corrosion resistance
• Right-hand cut, regular spiral, 2-flute design for efficient chip removal
• Straight-cylindrical shank fits standard drill chucks without adapters
• Rated for steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium
• Conforms to ANSI standards and NAS 907 specification

Compatibility

Designed as a general-purpose jobber-length drill bit compatible with any standard drill chuck sized to accept a 0.4130-inch straight-cylindrical shank, including benchtop drill presses, radial arm drills, and CNC machining centers. Suited for use across material groups P, M, K, N, and S as designated by the supplier specifications.

Installation Notes

A licensed machinist or qualified technician should secure the shank fully in a properly sized drill chuck and verify runout before drilling. Ensure the workpiece is clamped or fixtured to prevent movement during the cut. Apply cutting fluid appropriate to the workpiece material, particularly when drilling stainless steel, superalloys, or titanium. Do not exceed the recommended maximum drilling depth of 3.875 inches for this bit length.