Hertel 84578558 Jobber Drill Bit Letter D Hss Tin

Product Description

The HERTEL 84578558 is a jobber length drill bit sized to letter D (0.2460 inches) and designed for general-purpose metal drilling in production and maintenance environments. It is manufactured from high speed steel with a titanium nitride (TiN) coating that increases surface hardness and extends cutting life compared to uncoated HSS. The bit features a 118-degree standard point angle, a web-thinned tapered web for easier penetration at start, and a regular spiral with two flutes for efficient chip evacuation. Overall length is 4 inches with a 2-3/4 inch flute length. The straight-cylindrical shank fits standard three-jaw drill chucks. Machinists, maintenance mechanics, and fabricators are the primary users.

This bit is suited for drilling ferrous and non-ferrous metals, plastics, and wood composites in general shop and field applications. The letter D size (0.2460 inches decimal equivalent) falls within the 0.2000 to 0.2500 inch range, making it a common choice for tap drilling, clearance holes, and dowel pin work. Right-hand cutting direction is standard for conventional drill press and hand drill operation. The TiN coating is particularly useful in higher-cycle production drilling where uncoated bits wear quickly.

Key Features

• Letter D size — 0.2460 inch decimal equivalent for precise hole sizing
• TiN coating increases surface hardness and extends tool life over uncoated HSS
• 118-degree standard point angle for general-purpose drilling across common materials
• Web-thinned tapered web reduces thrust and improves center starting
• Two-flute regular spiral design promotes chip clearance and reduces heat buildup
• Straight-cylindrical shank fits standard drill chucks without adapters

Compatibility

Designed as a general-purpose jobber length drill bit compatible with any standard three-jaw drill chuck accepting a 0.2460 inch straight-cylindrical shank, including benchtop drill presses, CNC drilling machines, and hand drills.

Installation Notes

This bit is installed by a machinist or maintenance technician using a standard drill chuck key or keyless chuck. Ensure the workpiece is securely clamped before drilling and that the spindle speed is set appropriately for the material being drilled. Wear appropriate eye protection and follow applicable shop safety procedures. Inspect the cutting edges before use and replace the bit if chipping or excessive wear is present.