Osg 1295101 Extension Tap 1/4-28 Unf 2 Flute Spiral Point

Product Description

The OSG 1295101 is a spiral point plug extension tap designed for threading operations in ferrous and non-ferrous materials. Built from high-speed steel with a steam oxide finish, it produces right-hand internal threads to the 1/4-28 UNF standard at an H3 thread limit. The plug chamfer style allows threading in through-holes, while the extended 6.0-inch overall length and reduced shank design provide reach into deep or recessed bores that standard-length taps cannot access. At 0.638 inches of thread length and a 2-flute spiral point configuration, this tap pushes chips ahead of the cut to keep flutes clear during production runs.

This tap suits machining and maintenance applications involving cast iron, aluminum castings, aluminum, and carbon steel workpieces. The extended reach makes it well suited to production machining, toolroom work, and repair threading where standard-reach taps fall short. It is used by machinists, maintenance mechanics, and toolroom technicians on CNC equipment, drill presses, and hand-tapping setups. Thread class of fit is 3B, covering standard tolerance internal threads for general mechanical fastening.

Key Features

• Spiral point geometry pushes chips forward, reducing clogging in through-hole threading
• Extended 6.0-inch overall length with reduced shank for reach into deep or recessed bores
• High-speed steel construction provides durability across a range of workpiece materials
• Steam oxide finish improves lubricity and helps resist corrosion during storage and use
• H3 thread limit and 3B class of fit for standard tolerance internal thread production
• Right-hand flute and thread direction compatible with standard tapping equipment and tap handles

Compatibility

Suitable for threading 1/4-28 UNF through-holes in cast iron, aluminum casting, aluminum, and carbon steel. Fits standard tap holders and machine collets accepting a 0.255-inch shank diameter.

Installation Notes

Extension taps are installed by qualified machinists or maintenance mechanics using appropriate tap wrenches, tapping heads, or CNC rigid-tapping setups. Secure the workpiece before beginning the threading operation and confirm spindle speed and cutting fluid are appropriate for the workpiece material. Never force a tap through a hole undersize for the thread specification, and back off periodically when hand-tapping to break chips. Inspect the tap for wear or chipping before each use to avoid thread damage or breakage in the workpiece.