Osg 1301901903 Spiral Flute Tap 1/2-13 Unc Cobalt

Product Description

The OSG 1301901903 is a 1/2-13 UNC spiral flute tap designed for cutting right-hand internal threads in a modified bottoming configuration. Built from cobalt high-speed steel with a nitride finish, it handles tapping applications that demand heat and wear resistance. The 50-degree helix angle and 3-flute spiral geometry evacuate chips upward during the cut, making it well suited for blind-hole work where chip packing is a concern. At 3-3/8 inches overall length with an H3 thread limit and 2B class of fit, this tap delivers consistent tolerance control in production and job-shop environments. Machinists and tool-and-die professionals are the primary users.

This tap is rated for aluminum material applications, where the spiral flute geometry and nitride coating reduce built-up edge and promote clean thread formation. The modified bottoming chamfer allows threading closer to the bottom of a blind hole than a standard plug tap. With 13 threads per inch on a 1/2-13 UNC pitch, it covers one of the most common fastener sizes in general machining, maintenance, and repair work. Coolant-through is not available on this tap; external flood or mist coolant is the appropriate approach.

Key Features

• 50-degree helix angle promotes upward chip evacuation in blind holes
• Cobalt construction provides elevated heat and wear resistance versus standard HSS
• Nitride finish reduces friction and extends tool life in non-ferrous materials
• Modified bottoming chamfer for threading close to the bottom of blind holes
• H3 thread limit with 2B class of fit for consistent tolerance in production runs
• Right-hand flute and right-hand thread in a single unified configuration

Compatibility

Designed for use in standard 1/2-13 UNC tapping applications on aluminum workpieces; suitable for use in CNC machining centers, drill presses, and tapping arms that accept a straight shank tap of 6.48 mm shank diameter.

Installation Notes

Installation should be performed by qualified machinists familiar with tapping procedures and speeds appropriate to cobalt spiral flute taps. Ensure the workpiece is securely fixtured and the tap is properly aligned before engaging the cut to prevent tap breakage. Power down all equipment before loading or changing tooling. Because coolant-through is not supported, apply adequate external coolant or cutting fluid to the tap and hole throughout the operation.