Hertel 66693391 Screw Machine Drill Bit Letter a Tin Hss

Product Description

The HERTEL 66693391 is a screw machine length drill bit designed for high-production drilling in metal fabrication, machining, and general mechanical applications. Built from high-speed steel (HSS) with a titanium nitride (TiN) coating, it delivers extended tool life and reduced friction during cutting. The bit features a 135-degree split point that reduces walking on entry without a center punch, and a web-thinned, parallel web configuration that lowers thrust requirements. At 2-7/16 inches overall length with a 1-5/16-inch flute length, the screw machine format provides extra rigidity compared to jobber-length bits, making it well suited for drill press and CNC turret work where chatter control matters.

This bit is intended for use in machine shop environments, production drilling cells, and maintenance applications where consistent hole quality in metal is required. The 0.2340-inch decimal diameter corresponds to Letter A sizing and falls within the 0.2000 to 0.2500-inch drill bit size range. Right-hand spiral flute geometry pairs with the straight-cylindrical shank for secure chuck engagement in standard drill chucks and quick-change tool holders. The heavy-duty grade designation indicates suitability for interrupted cuts and tougher workpiece materials.

Key Features

• 135-degree split point reduces walk on entry and lowers required thrust force
• TiN coating extends tool life and reduces heat buildup at the cutting edge
• Web-thinned, parallel web construction decreases cutting resistance
• Screw machine length (2-7/16 inches OAL) provides added rigidity over jobber-length bits
• Straight-cylindrical shank fits standard drill chucks and quick-change holders
• Heavy-duty grade HSS construction rated for production drilling cycles

Compatibility

Designed as a screw machine length replacement or production drill bit for applications requiring a Letter A (0.2340-inch) diameter hole in metal using standard three-jaw drill chucks or quick-change tool holders with straight-shank capability.

Installation Notes

Installation and use should be performed by machinists or qualified mechanical tradespeople familiar with drill press, lathe, or CNC turret operation. Secure the straight-cylindrical shank firmly in the chuck before operation and verify runout is within acceptable tolerance for the application. Coolant through is not supported on this bit, so apply cutting fluid externally when drilling steel or other ferrous materials to manage heat. Inspect the cutting edges for wear or chipping before each production run and replace when drill point geometry is no longer intact.