Osg 1297100 Spiral Flute Extension Tap 10-24 Unc H3

Product Description

The OSG 1297100 is a spiral flute extension tap designed for threading 10-24 UNC holes in a range of ferrous and non-ferrous materials. Built from high-speed steel with a bright uncoated finish, it features a bottoming chamfer for threading close to the bottom of a blind hole. The 50-degree helix angle and right-hand flute direction help evacuate chips efficiently during the tapping operation. At 4 inches overall length, this extension tap reaches into deeper cavities than a standard-length tap, making it a practical choice when access is limited by surrounding structure or fixturing.

This tap is suited for production and maintenance threading applications in aluminum, carbon steel, and cast iron. The H3 thread limit provides a controlled fit tolerance appropriate for 2B and 3B class-of-fit requirements. Machinists, tool-and-die makers, and maintenance technicians use this tap in drill press, CNC, or hand-tapping operations where extra reach is needed. The reduced shank allows it to be held in standard tap collets and holders sized for the 0.194-inch shank diameter.

Key Features

• Bottoming chamfer allows threading to the base of blind holes
• 50-degree helix angle promotes upward chip evacuation in through and blind hole applications
• H3 thread limit for consistent 2B and 3B class-of-fit results
• 4-inch overall length provides extended reach in deep or obstructed workpiece locations
• High-speed steel construction handles aluminum, carbon steel, and cast iron
• Reduced shank compatible with standard tap holders sized for 0.194-inch shank diameter

Compatibility

Designed for use in standard tap holders and collet chucks that accept a 0.194-inch shank diameter. Suitable for threading 10-24 UNC threads to 2B and 3B class-of-fit tolerances in aluminum, carbon steel, and cast iron workpieces.

Installation Notes

Install in a tap holder or collet with sufficient torque capacity for the workpiece material before beginning the threading cycle. Power down or disengage the machine spindle before loading or removing the tap. Use appropriate cutting fluid for the material being tapped - sulfurized oil for steel and cast iron, a water-soluble coolant or kerosene for aluminum. Inspect the tap for chipping or wear before each use; a damaged tap can seize in the hole and damage the workpiece.