Osg 1294701 Extension Tap 10-32 Unf Spiral Point Hss

Product Description

The OSG 1294701 is a spiral point plug extension tap designed for threading operations in metalworking and machining applications. Built from high-speed steel with a steam oxide finish, this tap produces right-hand, 10-32 UNF internal threads with an H3 thread limit tolerance. The spiral point geometry pushes chips forward ahead of the cut, making it well suited for through-hole threading. Overall length is 4 inches, with a thread length of 0.875 inches, a shank diameter of 0.194 inches, and a 2B class of fit. The reduced shank design allows reach into recessed or extended locations where standard-length taps cannot access.

This extension tap is intended for use in production and repair threading of cast iron, aluminum castings, aluminum, and carbon steel workpieces. The 4-inch overall length provides clearance in deep cavities, fixtures, and close-quarter setups where a standard tap would bottom out on the holder or surrounding material. It is commonly used in machine tapping with CNC machining centers, drill presses, or hand tapping operations where controlled torque is applied. Machinists and tool and die professionals select this tap for production runs requiring consistent thread quality and chip evacuation in through-hole applications.

Key Features

• Spiral point geometry pushes chips ahead of the tap for clean through-hole threading
• High-speed steel construction provides wear resistance across a range of workpiece materials
• Steam oxide finish reduces friction and provides mild corrosion resistance during storage and use
• H3 thread limit ensures consistent 2B class of fit tolerances in production threading
• Reduced shank with 4-inch overall length extends reach into deep or recessed features
• Right-hand flute and thread direction compatible with standard tapping heads and holders

Compatibility

Designed for threading 10-32 UNF through-holes in cast iron, aluminum castings, aluminum, and carbon steel. Compatible with standard tapping chucks, holders, and CNC rigid tapping setups that accept a 0.194-inch shank diameter.

Installation Notes

Install in a tapping chuck or holder appropriate for the 0.194-inch shank and 0.152-inch square drive. Ensure the workpiece is securely fixtured and the spindle is aligned with the pre-drilled hole before engaging the tap. Apply cutting fluid appropriate for the workpiece material to extend tap life and improve thread finish. Inspect the tap for chipping or wear between uses, as a damaged tap can destroy the workpiece thread or break in the hole.