Precision Twist Drill 5999347 Jobber Drill Bit Letter R

Product Description

The PRECISION TWIST DRILL 5999347 is a jobber-length drill bit sized to letter R (0.3390 inches decimal equivalent), designed for general-purpose drilling in metal and hard materials. Built from high speed steel with a steam oxide coating, it runs a standard 118-degree point angle with a web-thinned, tapered web for improved chip clearance at entry. Overall length is 4.75 inches with a flute length of 3.4375 inches, giving it the reach typical for through-hole and deep-feature work in production and maintenance drilling. Licensed HVAC techs, machinists, pipefitters, and general trade professionals reach for this size when drilling pilot holes, clearance holes, and tap-drill applications across a wide range of base metals.

This bit is suited for drilling steel, stainless steel, cast iron, non-ferrous metals, superalloys, and titanium. It fits standard drill chucks via its straight-cylindrical shank (0.3390 inches diameter, 1.3125 inches shank length). The right-hand spiral flute and regular spiral type make it compatible with conventional drill presses, hand drills, and CNC drilling setups in both shop and field environments. Maximum drilling depth reaches 3.4375 inches, aligning with the 10xD flute-to-diameter ratio of the R10-R15-R18 series.

Key Features

• Letter R size — 0.3390 inches decimal equivalent for precise hole sizing
• 118-degree standard point angle with web thinning for reduced thrust and cleaner entry
• Steam oxide coating improves lubricity and provides basic corrosion resistance during storage and use
• High speed steel construction handles steel, stainless, cast iron, non-ferrous metals, and superalloys
• Straight-cylindrical shank fits standard 3-jaw drill chucks without adapters
• 2-flute right-hand spiral design promotes efficient chip evacuation in through-hole drilling
• Conforms to ANSI standards for jobber-length drill bits

Compatibility

Designed as a general-purpose jobber-length drill bit conforming to ANSI standards, compatible with any standard drill chuck accepting a 0.3390-inch straight shank. Suitable for use in drill presses, hand drills, and CNC drilling equipment across production, maintenance, and field applications.

Installation Notes

Install in a properly sized drill chuck and tighten securely before operation. Secure the workpiece with a vise or clamp — never hand-hold metal stock during drilling. Apply cutting fluid when drilling stainless steel, superalloys, or titanium to manage heat and extend bit life. Replace the bit if the cutting edges show visible wear, chipping, or if the bit begins to wander at entry.