Osg 2885705 Spiral Point Tap 1/4-28 Unf Tin Hss

Product Description

The OSG 2885705 is a spiral point tap designed for cutting internal threads in through-hole applications. It features a 1/4-28 UNF thread form with a plug chamfer and three flutes, manufactured from high-speed steel with a titanium nitride (TiN) coating for improved wear resistance and tool life. The spiral point geometry pushes chips forward ahead of the tap, keeping the flutes clear during the cut. This tap is suited for production tapping in CNC machining centers and drill presses where through-hole access allows chip evacuation. It carries an H3 thread limit and a 2B class of fit, making it appropriate for standard commercial thread tolerances.

This tap is used in light to medium machining of aluminum, cast aluminum, low-carbon steel, and medium-carbon steel. It is well-suited for through-hole tapping operations in job shop, production, and maintenance-repair environments. The right-hand thread direction and plug chamfer make it a standard choice for machine tapping where the tap enters from one side and chips exit through the opposite end of the hole.

Key Features

• Spiral point geometry pushes chips forward, reducing clogging in through-hole applications
• TiN coating improves surface hardness and extends tool life compared to uncoated HSS
• H3 thread limit with 2B class of fit meets standard commercial thread tolerance requirements
• Plug chamfer provides 3-5 thread lead-in for guided entry and gradual thread engagement
• Compatible with aluminum, cast aluminum, low-carbon steel, and medium-carbon steel workpieces
• No coolant-through requirement — suited for flood or drip coolant setups

Compatibility

Designed for through-hole tapping of 1/4-28 UNF threads in aluminum, cast aluminum, low-carbon steel, and medium-carbon steel. Part of OSG Series 287.

Installation Notes

Spiral point taps are installed by machinists in drill presses, CNC machining centers, and tapping machines. Before tapping, ensure the pilot hole is drilled to the correct tap drill diameter for a 1/4-28 UNF thread and that the workpiece is securely fixtured. Use appropriate cutting fluid for the workpiece material — sulfur-based oil for steel, water-soluble coolant or kerosene for aluminum. Do not use this tap in blind holes, as the spiral point is designed to push chips forward through the hole exit.