Osg 1400128200 Thread Forming Tap 1/4-28 Unf Cobalt Hy-pro Nrt

Product Description

The OSG 1400128200 is a thread forming tap in the HY-PRO NRT series, designed for cold-forming internal threads without cutting. It produces a 1/4-28 UNF right-hand thread using a modified bottoming chamfer with 2 to 2.5 chamfered threads, making it suitable for blind hole applications where thread depth is critical. The tap is made from cobalt high-speed steel with a bright finish and carries an H2 thread limit. Overall length is 2.5 inches, with a thread length of 0.594 inches and a tapping depth of 0.933 inches. Shank diameter is 0.255 inches. Licensed HVAC, mechanical, and industrial technicians use this tap for precision threading in tight-tolerance assemblies.

This tap is intended for blind hole threading in a range of metallic workpiece materials. Its cobalt construction handles demanding materials including alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. The modified bottoming chamfer allows threading close to the bottom of a blind hole, which is common in manifold blocks, bracket fasteners, and structural assemblies across HVAC, refrigeration, and general mechanical trade work. The H2 thread limit provides a standard fit suitable for most UNF fastener pairings.

Key Features

• Thread forming design displaces material rather than cutting, producing stronger threads with no chips
• Cobalt high-speed steel construction for use in hardened steel, stainless steel, and other tough alloys
• Modified bottoming chamfer with 2 to 2.5 chamfered threads for blind hole threading close to the hole bottom
• H2 thread limit for consistent, standard-fit 1/4-28 UNF thread geometry
• Bright finish with no coolant-through requirement, simplifying setup in standard drill press or tapping operations
• Right-hand thread direction compatible with standard tapping equipment and tap handles

Compatibility

Designed for blind hole threading in alloy steel, aluminum, carbon steel, die steel, hardened steel, and stainless steel workpieces. Material application codes P and N confirm suitability across ferrous and non-ferrous base metals requiring a 1/4-28 UNF thread form.

Installation Notes

Thread forming taps require a specific tap drill size for the UNF thread form — consult the OSG HY-PRO NRT drill chart for the correct hole diameter before tapping, as forming taps use a larger pilot hole than cutting taps of the same thread size. Ensure the workpiece is securely fixtured and apply appropriate tapping fluid for the base material, particularly when working with stainless or hardened steel. Use a calibrated torque-limiting tap handle or CNC rigid tapping cycle to avoid overloading the tap shank. Always power down and de-energize any machine tool before changing or inspecting tooling.