Precision Twist Drill 5998975 Letter O Hss Drill Bit

Product Description

The PRECISION TWIST DRILL 5998975 is a jobber length drill bit sized to Letter O (0.3160 inches decimal), designed for general-purpose drilling in demanding trade environments. Built from high speed steel with a steam oxide coating, it runs a 135-degree split point that reduces walking and improves bite on hard materials. Overall length is 4.5 inches with a 3.1875-inch flute length, giving machinists and maintenance techs adequate reach for most standard drilling applications. The straight-cylindrical shank seats cleanly in keyed or keyless chucks without slipping. This is a heavy duty grade bit suited to production and field work alike.

This bit is rated for drilling steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium. It follows a 10xD flute-to-diameter ratio, supporting maximum drilling depths up to 3.1875 inches. The tapered web with web thinning reduces thrust requirements when pushing into tough workpieces. Typical users include machinists, millwrights, maintenance mechanics, and fabricators working in shops or in the field. It meets ANSI standards and carries NAS 907 specification designation, making it appropriate for aerospace and precision manufacturing environments where spec compliance is required.

Key Features

• Letter O size — 0.3160 inches decimal diameter for precise hole sizing
• 135-degree drill point angle reduces walking and improves centering on hard surfaces
• Steam oxide coating provides corrosion resistance and mild lubricity during cutting
• Web-thinned, tapered web lowers thrust and extends tool life in tough materials
• 2-flute spiral design with right-hand cut for standard drilling operations
• Meets ANSI standards and NAS 907 specification — suitable for precision and aerospace applications

Compatibility

Designed as a general-purpose jobber length drill bit compatible with any standard keyed or keyless drill chuck accepting a 0.3160-inch straight-cylindrical shank. Suitable for drilling steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium. Part of the R10B-R15B-R18B series.

Installation Notes

Installation and use should be performed by qualified machinists or mechanics familiar with proper drilling technique and machine guarding requirements. Secure the workpiece fully before drilling and confirm the chuck is tightened to prevent shank slippage. Always wear appropriate eye protection and follow applicable shop safety standards when operating drilling equipment. Do not exceed the rated maximum drilling depth of 3.1875 inches without retracting to clear chips.