Osg 1400135301 Thread Forming Tap 3/8-16 Unc Cobalt

Product Description

The OSG 1400135301 is a thread forming tap designed for cold-forming internal threads without cutting or producing chips. Built from cobalt high-speed steel with a steam oxide coating, this tap is engineered for blind hole threading in demanding materials including alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. At 2.9380 inches overall length with a 0.7520-inch thread length and a 0.3810-inch shank diameter, it suits standard tapping chucks and holders used in production and maintenance environments. The modified bottoming chamfer with 2 to 2.5 chamfered threads allows threading close to the bottom of blind holes. Licensed machinists, tool-and-die makers, and CNC operators are the primary users.

This tap is suited to blind hole threading applications across both production machining and job shop settings. It performs in ferrous and non-ferrous materials, including alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. The cold-forming action produces stronger threads than cut tapping by work-hardening the material around the thread form. The H7 thread limit and 2B class of fit make it appropriate for standard commercial threaded fastener assemblies. It is part of the OSG HY-PRO NRT series, which is purpose-built for thread forming in through and blind holes across a range of machining platforms.

Key Features

• Thread forms a 3/8-16 UNC right-hand internal thread without chip production, reducing the risk of chip packing in blind holes
• Cobalt construction provides heat and wear resistance in tough ferrous and stainless steel applications
• Steam oxide coating improves lubricity and corrosion resistance during storage and use
• Modified bottoming chamfer with 2 to 2.5 chamfered threads allows threading near the base of blind holes
• H7 thread limit and 2B class of fit conform to standard UNC tolerance requirements
• Tapping depth of 1.2520 inches with a square drive size of 0.2860 inches for positive drive engagement

Compatibility

Designed for use in blind hole threading applications in alloy steel, aluminum, carbon steel, die steel, hardened steel, and stainless steel workpieces requiring a 3/8-16 UNC 2B internal thread form.

Installation Notes

Thread forming taps require a specific forming tap drill size that differs from standard cut tap drill charts — always consult OSG or a thread forming drill chart before drilling the pilot hole. Use a tapping fluid or cutting oil appropriate for the workpiece material, as thread forming generates significant radial pressure. Secure the workpiece and tap holder firmly to prevent misalignment that can cause tap breakage. Follow applicable OSHA machine guarding requirements and shop safety procedures when operating tapping equipment.