Hertel 77428670 Reduced Shank Drill Bit 41/64 in Hss

Product Description

The HERTEL 77428670 is a reduced shank twist drill bit ground from high-speed steel and finished with a black oxide coating. The cutting diameter measures 41/64 inches (0.6406 inches decimal), while the Weldon flat shank reduces to 1/2 inch to fit standard chucks and toolholders without requiring a larger spindle bore. The 118-degree standard point angle suits general-purpose drilling in a wide range of ferrous and non-ferrous workpiece materials. Overall length is 6 inches with a 3-inch spiral flute length, and the right-hand cut spiral flutes evacuate chips efficiently during through-hole and blind-hole operations. Weight is 0.4 pounds.

This drill bit is intended for use in machine shop, maintenance, and production drilling applications where a full-shank bit would exceed the toolholder capacity. It is well suited for drill presses, milling machines, and CNC machining centers equipped with 1/2-inch Weldon-style holders. Primary workpiece materials include low and medium tensile strength steels, cast iron, aluminum, and similar materials. The 3-inch flute length supports drilling depths up to 3 inches per the manufacturer specification, making it practical for moderate-depth hole-making in plate, structural, and fabricated components.

Key Features

• 41/64 inch cutting diameter (0.6406 inches decimal) with a reduced 1/2 inch Weldon flat shank for broad toolholder compatibility
• High-speed steel construction provides hardness and wear resistance for general-purpose metal drilling
• Black oxide finish reduces friction and provides light corrosion resistance during storage and use
• 118-degree standard point angle for self-centering entry on flat and slightly curved surfaces
• Three-flat Weldon shank design resists rotational slippage in the holder under torque
• Right-hand spiral flutes promote chip ejection and reduce heat buildup during drilling

Compatibility

Designed as a direct-fit reduced shank drill bit for 1/2 inch Weldon-style toolholders and end-mill holders used on drill presses, knee mills, and CNC machining centers. Suitable for drilling low and medium tensile strength materials.

Installation Notes

Installation and use should be performed by a qualified machinist or tool-and-die professional. Secure the Weldon flat against the set screw in the toolholder before applying power; ensure the set screw contacts the flat directly to prevent shank rotation. Verify spindle speed is appropriate for the workpiece material and hole diameter before drilling. Inspect the cutting edges for wear or chipping before each use, and replace the bit if edge condition has degraded to avoid workpiece damage or toolholder stress.