Hertel 66691502 Screw Machine Drill Bit Letter a Cobalt

Product Description

The HERTEL 66691502 is a screw machine length drill bit sized to Letter A (0.2340 inches, 15/64 inches) 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, giving them added rigidity and reduced deflection in production and maintenance drilling applications. The split point geometry starts on contact without a center punch, reducing walking on hard or coated surfaces. The TiN coating lowers friction and extends cutting edge life compared to uncoated cobalt. Intended for use by machinists, maintenance technicians, and metalworking professionals.

This bit is suited for drilling ferrous metals, stainless alloys, and other hard materials where a standard high-speed steel bit would dull prematurely. Screw machine length geometry makes it a common choice for drill press work, CNC setup, and bench drilling in job shops, MRO environments, and industrial maintenance settings. The straight-cylindrical shank fits standard three-jaw drill chucks across all common machine spindle sizes in the 15/64-inch range.

Key Features

• Letter A size - 0.2340 inches decimal equivalent (15/64 inches)
• 135-degree split point starts on contact and reduces drill walking
• Cobalt construction rated for heavy-duty drilling in hard and abrasive metals
• TiN coating reduces friction and extends tool life versus uncoated bits
• Web-thinned parallel web design improves chip evacuation and reduces thrust load
• Screw machine (stub) length increases rigidity and minimizes deflection

Compatibility

Designed as an OEM-style replacement or standard addition to tooling inventories requiring a Letter A screw machine length drill bit with a straight-cylindrical shank. Fits any drill press, CNC turret, or hand drill chuck accepting a 0.2340-inch straight shank.

Installation Notes

Installation is performed by machinists or maintenance technicians familiar with metal cutting operations. Secure the straight-cylindrical shank fully in a drill chuck before operation and verify runout before cutting. Always match spindle speed and feed rate to the workpiece material and bit diameter - cobalt bits tolerate higher heat than HSS but still require appropriate cutting fluid or coolant for prolonged production runs. Inspect the cutting edges before each use and replace when signs of chipping or dulling are present.