Osg 1400105308 Thread Forming Tap 4-40 Unc Cobalt Ticn

Product Description

The OSG 1400105308 is a thread forming tap designed for cutting 4-40 UNC internal threads in blind hole applications. Unlike cutting taps, this forming tap displaces material rather than removing it, producing stronger threads with no chip generation. It is built from cobalt high-speed steel for increased heat and wear resistance, and carries a TiCN coating to further extend tool life under demanding conditions. The modified bottoming chamfer with 2 to 2.5 chamfered threads allows threading close to the bottom of a blind hole. This tap is sized at 1.875 inches overall length with a shank diameter of 0.141 inches, suited for precision small-fastener work in machine shops and assembly operations.

This tap is intended for threading operations in alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum workpieces. The right-hand thread direction and Class 3B fit with H3 thread limit make it appropriate for close-tolerance production threading. It is commonly used by machinists, toolmakers, and maintenance technicians working with 4-40 fastener applications on fixtures, enclosures, and precision assemblies. The HY-PRO NRT series designation indicates it is part of a thread forming product line optimized for ductile and semi-ductile materials.

Key Features

• Thread forming design displaces material for chip-free blind hole threading
• Cobalt construction provides superior heat resistance over standard HSS
• TiCN coating reduces friction and extends tool life in abrasive materials
• Modified bottoming chamfer with 2 to 2.5 chamfered threads for near-bottom thread depth
• H3 thread limit with Class 3B fit for close-tolerance thread production
• Right-hand 4-40 UNC thread specification at 40 threads per inch

Compatibility

Designed for blind hole thread forming in alloy steel, aluminum, carbon steel, die steel, hardened steel, and stainless steel workpieces requiring 4-40 UNC internal threads to a Class 3B fit standard.

Installation Notes

Thread forming taps require a properly sized forming tap drill hole, which differs from a standard cut tap drill size — consult a forming tap drill chart before drilling. This tool should be installed in a rigid or floating tap holder appropriate for the machine type. Adequate lubrication or cutting fluid compatible with the workpiece material is required to prevent galling, particularly in stainless steel. Secure the workpiece fully before tapping and verify spindle alignment to avoid tap breakage.