Hertel 66691684 Screw Machine Drill Bit Letter S Cobalt

Product Description

The HERTEL 66691684 is a screw machine length drill bit designed for high-production drilling in metal and hard materials. Built from heavy-duty cobalt steel with a titanium nitride (TiN) coating, it delivers extended tool life in abrasive and work-hardening materials such as stainless steel, cast iron, and high-alloy steels. The 135-degree split point with web thinning reduces thrust, improves chip evacuation, and allows self-centering starts without a pilot hole. The straight-cylindrical shank provides secure chuck grip in standard drill chucks and CNC toolholders. At 3-1/16 inches overall length with a 1-3/4 inch flute length, this screw machine geometry offers greater rigidity than jobber-length bits in tight-clearance applications.

This bit is suited for use in machining centers, drill presses, and hand-held power tools where a Letter S diameter of 0.3480 inches is required. The screw machine length format is common in production environments and sheet metal shops where stub-length rigidity reduces chatter and deflection. Right-hand spiral flute geometry with a regular helix is appropriate for standard metal drilling operations. This is a single-bit package intended for toolroom replenishment, job-site replacement, or low-volume production use.

Key Features

• Letter S diameter: 0.3480 inches, within the 0.3000 to 0.3500 inch size range
• 135-degree split point with web thinning reduces entry thrust and self-centers on contact
• Cobalt steel construction rated for heavy-duty use in hard and abrasive metals
• TiN coating extends surface hardness and reduces friction at the cutting edge
• Screw machine (stub) length provides greater rigidity than jobber-length bits
• Straight-cylindrical shank fits standard 3-jaw chucks and collet-style toolholders
• Right-hand cutting with regular spiral flute for efficient chip removal in through-hole drilling

Compatibility

Designed as a screw machine length drill bit for use in any standard drill press, machining center, or power drill accepting a 0.3480 inch straight-cylindrical shank. Fits toolholders and chucks sized for the Letter S decimal equivalent diameter range.

Installation Notes

Installation and use of this drill bit should be performed by a qualified machinist or tooling technician familiar with metal cutting operations. Ensure the machine spindle is fully stopped and secured before mounting or removing the bit. Verify chuck or collet runout before use, as excessive runout accelerates tool wear and reduces hole accuracy. Follow the machine manufacturer and applicable shop safety guidelines for cutting speeds, feed rates, and coolant application.