Hertel 04139481 Cobalt Jobber Drill Bit Letter U

Product Description

The HERTEL 04139481 is a heavy-duty cobalt jobber drill bit sized to Letter U (0.3680 inches decimal) with a 135-degree split point and an oxide and TiN coating. Designed for right-hand cutting, this bit features a regular spiral flute and a straight-cylindrical shank, making it a direct fit into standard drill chucks. The split point geometry allows the bit to start on contact without a center punch, reducing walking on hard or smooth surfaces. At 5 inches overall length with a 3-5/8 inch flute, it handles typical through-hole and deep-drilling tasks in production or field environments. Machinists, millwrights, and maintenance mechanics reach for cobalt tooling when drilling alloy steels, stainless, and other hard-to-machine materials.

This jobber drill is suited for general holemaking in metal fabrication shops, maintenance and repair operations, and production drilling environments. The heavy-duty cobalt construction handles elevated heat generated when cutting harder ferrous and non-ferrous alloys where high-speed steel bits lose their edge. The web-thinned, tapered web configuration reduces thrust requirements, improving efficiency in hand-held drill applications as well as drill press and mill setups. Coolant-through capability is not available on this model, so external coolant or cutting fluid application is recommended when drilling deep holes in heat-sensitive materials.

Key Features

• Letter U size — 0.3680 inches decimal for precise fitment
• 135-degree split point starts on contact and reduces walking without center punching
• Cobalt construction retains hardness at elevated cutting temperatures
• Oxide and TiN coating improves lubricity and extends cutting life
• Web-thinned tapered web reduces drilling thrust and operator fatigue
• Right-hand regular spiral flute provides efficient chip evacuation

Compatibility

Designed as a standard jobber-series drill bit with a straight-cylindrical shank, compatible with any 3-jaw or keyed drill chuck accepting a 0.3680-inch shank diameter. Suitable for drill presses, mills, and hand-held drills configured for right-hand cutting.

Installation Notes

Installation and use of this drill bit should be performed by qualified machinists or tradespeople following applicable shop safety practices. Ensure the drill chuck is fully tightened and the workpiece is securely clamped before beginning any drilling operation. Apply cutting fluid or external coolant when drilling deep holes or working with heat-sensitive alloys to prevent premature tool wear. Inspect the cutting edges before each use and replace the bit if chipping or wear is detected.