Osg 1651501508 Spiral Point Tap 12-28 Unf Ticn

Product Description

The OSG 1651501508 is a high-performance spiral point tap designed for cutting 12-28 UNF internal threads in a wide range of metallic workpiece materials. Built from powdered metal high-speed steel (PMT15 grade) and finished with a TiCN coating, it delivers improved wear resistance and longer tool life compared to standard HSS taps. The plug chamfer style provides progressive thread engagement suited to through-hole tapping operations. With 3 flutes and an H3 thread limit, this tap produces Class 2B fit threads, the standard tolerance class for most general-purpose fastener applications. Overall length is 3.15 inches with a thread length of 0.496 inches.

This tap is intended for use in machine tapping operations on ferrous and non-ferrous metals including alloy steel, low-carbon steel, medium-carbon steel, high-carbon steel, cast iron, hardened steel, die steel, stainless steel, aluminum, cast aluminum, and similar materials. It is suited to CNC machining centers, drill presses, and tapping machines where controlled feed and rigid toolholding are used. The 0.220-inch shank diameter fits standard collet and tap holder systems used in production and job-shop environments. It does not include coolant-through capability, so external flood or mist coolant is appropriate for most applications.

Key Features

• Spiral point geometry pushes chips forward through the hole, keeping the flutes clear during through-hole tapping
• Powdered metal HSS (PMT15 grade) provides higher hardness and toughness than conventional HSS
• TiCN coating reduces friction and increases surface hardness for extended tap life in abrasive materials
• Plug chamfer distributes cutting load across multiple leading threads for smooth thread entry
• H3 thread limit and Class 2B fit meet standard tolerance requirements for most UNF fastener assemblies
• Right-hand cut, no interrupted thread design for use in clean, uninterrupted through-hole applications

Compatibility

Designed for through-hole tapping of 12-28 UNF threads in alloy steel, aluminum, cast aluminum, cast iron, hardened steel, high-carbon steel, low-carbon steel, medium-carbon steel, stainless steel, and die steel workpieces. Part of OSG Series 16515.

Installation Notes

This tap is installed and operated by machinists using compatible collet chucks, tap holders, or floating tap heads sized for the 0.220-inch shank. Ensure the spindle speed and feed rate are set per the tap manufacturer recommendations for the workpiece material before starting the cut. Secure the workpiece firmly and confirm proper hole diameter for 12-28 UNF before tapping. Do not reverse-feed manually against the spiral point geometry; always allow the machine cycle to control retraction.