Hertel 04139531 Cobalt Jobber Drill Bit Letter Z 135 Deg

Product Description

The HERTEL 04139531 is a cobalt jobber-length drill bit sized to letter Z (0.4130 inches) with a 135-degree split point and oxide/gold coating. Built for heavy-duty holemaking in metals, it features a right-hand spiral flute and a straight-cylindrical shank for use in standard drill chucks and CNC spindles. The split point geometry reduces walking on entry and lowers thrust requirements compared to a conventional 118-degree point. Web thinning at the tip further reduces cutting resistance, making this bit well-suited for production drilling in steel, stainless, cast iron, and other ferrous materials where tool life under heat and pressure is critical.

This drill bit is intended for machinists, maintenance technicians, fabricators, and metalworking tradespeople performing holemaking operations in shop and field environments. The jobber-series length provides a practical balance of reach and rigidity for general-purpose through-hole and blind-hole drilling. The 0.4130-inch diameter and letter Z sizing make it a common selection for tapping prep and close-tolerance hole applications in ferrous and hard non-ferrous stock.

Key Features

• Letter Z size: 0.4130 inches decimal equivalent for precise hole sizing
• 135-degree split point reduces bit walking and cutting thrust on hard materials
• Cobalt construction provides elevated heat resistance over standard HSS for drilling tough alloys
• Oxide/gold coating adds lubricity and corrosion resistance to extend tool life
• Web-thinned, tapered web configuration lowers cutting force requirements
• Right-hand spiral flute with regular helix for efficient chip evacuation
• Straight-cylindrical shank fits standard 3-jaw chucks and collet holders

Compatibility

Designed as a standard jobber-length drill bit for use in drill presses, CNC machining centers, hand drills, and other rotating spindle equipment accepting a straight-cylindrical shank at 0.4130 inches diameter.

Installation Notes

Installation and use should be performed by qualified machinists or metalworking tradespeople following applicable shop safety practices. Ensure the machine spindle is fully stopped and locked out before inserting or removing the bit from the chuck or collet. Secure the shank fully in the chuck to the recommended grip depth to prevent slippage under load. Use appropriate cutting fluid or coolant for the workpiece material to maximize tool life and hole quality; this bit does not support through-coolant delivery.