Hertel 66691601 Letter K Cobalt Screw Machine Drill Bit

Product Description

The HERTEL 66691601 is a screw machine length drill bit sized to Letter K (9/32 inch, 0.2810 inch decimal) with a 135-degree split point and a titanium nitride (TiN) coating over a cobalt steel body. Screw machine length bits are shorter than jobber-length bits, which improves rigidity and reduces deflection in high-cycle drilling applications. The 135-degree split point self-centers on contact and reduces the thrust required to start a hole. Right-hand spiral flutes evacuate chips efficiently. This bit is installed and used by machinists, maintenance technicians, and sheet metal fabricators working with harder materials where cobalt tooling is the appropriate choice.

Screw machine length cobalt drill bits are suited for production drilling, CNC work, and manual drilling operations in harder steels, stainless steel, cast iron, and heat-resistant alloys. The shorter overall length of 2-11/16 inches provides increased stability in drill presses, turret lathes, and screw machines. The straight cylindrical shank fits standard 3-jaw drill chucks without adapters. This is a heavy-duty grade bit appropriate for demanding shop environments and repetitive drilling cycles where standard high-speed steel bits wear prematurely.

Key Features

• Letter K size: 9/32 inch (0.2810 inch decimal) cutting diameter
• 135-degree split point self-centers and reduces thrust load at entry
• Cobalt steel construction handles elevated heat in hard-material drilling
• TiN coating adds surface hardness and extends cutting edge life
• Screw machine length (2-11/16 inches OAL) improves rigidity over jobber-length bits
• Web-thinned parallel web reduces torque requirements
• Right-hand cut, regular spiral with 1-1/2 inch flute length for efficient chip evacuation

Compatibility

Fits any standard drill chuck accepting a 0.2810-inch straight cylindrical shank. Suitable for drill presses, CNC machining centers, turret lathes, and hand-held electric drills used in metalworking applications requiring Letter K diameter holes.

Installation Notes

Secure the straight cylindrical shank fully in a 3-jaw or keyless chuck before use. Always power down and lock out the machine before changing bits. Use cutting fluid appropriate for the workpiece material when drilling hard steels or stainless to maximize tool life. Ensure the workpiece is firmly clamped before starting the cut to prevent bit walk or breakage.