Osg 1295001 Extension Tap 1/4-20 Unc 2 Flute H3 Spiral Point

Product Description

The OSG 1295001 is a spiral point plug extension tap designed for threading operations in materials including cast iron, aluminum castings, aluminum, and carbon steel. Built from high-speed steel with a steam oxide finish, this tap handles 1/4-20 UNC right-hand threads at an H3 thread limit, which controls tolerance for reliable fit in production and repair threading. The plug chamfer eases entry into through-holes, and the spiral point geometry pushes chips forward ahead of the cutting teeth. With a 6-inch overall length, the 1295001 provides the reach needed for deep or obstructed threading setups where a standard-length tap cannot access the workpiece.

This tap is suited for machining operations, maintenance shops, and field repair scenarios where threading into through-holes in cast iron, aluminum, or carbon steel components is required. The extended 6-inch overall length makes it practical for fixtures, deep bosses, or confined assemblies. The 2-flute design keeps the tap body slim for small-diameter work. A reduced shank and 0.255-inch shank diameter allow use in standard tap holders and extension chucks common in both CNC and manual machine setups.

Key Features

• 1/4-20 UNC right-hand thread, H3 thread limit for controlled tolerance
• Spiral point plug tap geometry drives chips forward through the hole
• High-speed steel construction suitable for cast iron, aluminum, and carbon steel
• Steam oxide finish provides mild lubricity and corrosion resistance during storage and use
• 6-inch overall length delivers extended reach for deep or obstructed work
• Reduced shank with 0.255-inch shank diameter fits standard tap holders

Compatibility

Designed for use with standard 1/4-20 UNC through-hole threading applications in cast iron, aluminum castings, aluminum, and carbon steel workpieces. Compatible with standard tap holders, T-handle wrenches, and extension chucks accepting a 0.255-inch reduced shank diameter.

Installation Notes

Extension taps of this type are installed by machinists and maintenance technicians using manual tap handles, drill press setups, or CNC tapping heads. Always ensure the workpiece is securely fixtured and the tap is properly aligned to the drilled hole before applying torque. Use an appropriate cutting fluid for the workpiece material to extend tap life and reduce the risk of breakage. Inspect the tap for wear or chipping before each use, as broken tap removal from small-diameter holes is time-consuming.