Hertel 66693573 Screw Machine Drill Bit Letter T Hss Tin

Product Description

The HERTEL 66693573 is a screw machine length drill bit sized to Letter T (0.3580 inches) with a 135-degree split point and a titanium nitride (TiN) coating over a high-speed steel body. Screw machine length bits are shorter than jobber-length bits, which increases rigidity and reduces deflection in production drilling and close-tolerance work. The split point geometry starts on contact without a center punch and reduces thrust load. The TiN coating improves surface hardness and extends tool life in ferrous materials. This bit is installed and used by machinists, tool-room technicians, and maintenance mechanics working on drill presses, CNC machining centers, and hand-held power tools.

This bit is suited for production and maintenance drilling in steel, cast iron, and similar ferrous stock where a compact, rigid drill is preferred over a standard jobber-length bit. The 1.75-inch flute length and 3-1/16-inch overall length make it a practical choice for drilling in tight clearances or on short-travel drill press spindles. The straight cylindrical shank fits standard three-jaw drill chucks without an adapter. Right-hand cutting direction is standard for conventional drill press and CNC spindle rotation.

Key Features

• Letter T size - 0.3580 inches decimal equivalent for precise hole sizing
• 135-degree split point starts on contact and reduces walking without center-punching
• TiN coating increases surface hardness and extends tool life over uncoated HSS
• Web-thinned, parallel web design lowers thrust and improves chip clearance
• Screw machine length body increases rigidity and reduces deflection versus jobber length
• Heavy-duty grade construction rated for production drilling applications

Compatibility

Designed as a standard screw machine length drill bit fitting any three-jaw drill chuck or collet system that accepts a 0.3580-inch straight cylindrical shank.

Installation Notes

A licensed machinist or qualified maintenance technician should install this bit in a properly rated drill chuck, confirming the shank is fully seated and the chuck is tightened at all three jaws. Power down and lock out the machine before changing bits. No coolant-through capability is present on this tool, so external cutting fluid or cutting oil should be applied when drilling ferrous materials to manage heat buildup. Inspect the cutting edges and TiN coating for wear or chipping before each use.