Chicago-latrobe 70318 Drill Bit Letter R 0.3390 in Hss Tin

Product Description

The CHICAGO-LATROBE 70318 is a jobber-length drill bit sized to letter R, equal to 0.3390 inches in diameter, built from high speed steel with a titanium nitride (TiN) coating. It features a 118-degree standard point angle with web thinning on a tapered web for easier penetration and reduced thrust. The straight-cylindrical shank measures 0.3390 inches in diameter and 1.3125 inches in length. At 4.75 inches overall length with a 3.4375-inch flute, this is a general-purpose bit sized for repeated use in production and maintenance drilling. It is installed and used by machinists, pipefitters, and maintenance mechanics working in metal fabrication, HVAC, or plumbing rough-in environments.

This bit is rated for drilling cast iron and steel and is suited for handheld drill motors, drill presses, and magnetic base drills in both shop and field settings. The right-hand spiral flute promotes chip evacuation during through-hole drilling. The Series 150T designation places it within CHICAGO-LATROBE's general-purpose TiN-coated jobber line, which is commonly stocked by tradespeople for everyday structural and mechanical drilling tasks where a standard twist drill is specified.

Key Features

• Letter R size: 0.3390 inches diameter for precise hole sizing
• Titanium nitride (TiN) coating increases surface hardness and extends tool life in ferrous materials
• 118-degree standard point with web thinning reduces entry thrust and centering effort
• Right-hand spiral flute efficiently clears chips during drilling
• Straight-cylindrical shank fits standard drill chucks without adapters
• Meets DIN 338 standard for jobber-length geometry and tolerances
• Diameter tolerance of -0.0010 to 0.0000 inches ensures consistent hole sizing

Compatibility

Designed as a general-purpose jobber-length drill bit compatible with any drill chuck accepting a 0.3390-inch straight-cylindrical shank, including handheld drill motors, drill presses, and magnetic base drills. Primary workpiece materials are cast iron and steel per manufacturer specification.

Installation Notes

Secure the straight-cylindrical shank firmly in a properly sized drill chuck before operation, and confirm the chuck key is removed before powering the drill. Use cutting fluid or coolant when drilling steel at sustained depths to preserve coating life, though this bit is not configured for internal coolant delivery. Always wear eye protection and secure the workpiece before drilling. Dull or chipped cutting edges should not be forced through material; regrinding or replacement is the correct course of action.