Osg 1400129400 Thread Forming Tap 1/4-28 Unf Plug Cobalt

Product Description

The OSG 1400129400 is a thread forming tap in the HY-PRO NRT series, designed for cold-forming internal threads without cutting. Rather than removing material, this tap displaces it, producing strong, work-hardened threads with no chips. Built from cobalt high-speed steel with a bright finish, it handles a 1/4-28 UNF thread profile in a plug chamfer style. At 2.5 inches overall length with a 0.594-inch thread length and an H5 thread limit, it is suited for precision threading in production and maintenance environments. Right-hand thread direction and a 4 to 4.5 chamfered thread count deliver reliable, repeatable starts in through-hole applications.

This tap is intended for through-hole threading operations across a range of metals. Its cobalt construction makes it appropriate for demanding materials including alloy steel, carbon steel, die steel, hardened steel, stainless steel, and aluminum. It fits standard tap handles and machine setups used by machinists, tool-and-die makers, maintenance mechanics, and production shops requiring consistent 1/4-28 UNF internal threads. The HY-PRO NRT series is OSG's dedicated line for thread forming, offering high thread quality with reduced tool breakage risk compared to cutting taps in ductile materials.

Key Features

• Thread forming design produces chip-free, work-hardened threads in through-hole applications
• Cobalt high-speed steel construction for durability in alloy steel, stainless steel, and hardened steel
• 1/4-28 UNF plug chamfer profile with 4 to 4.5 chamfered threads for reliable thread starts
• H5 thread limit for consistent tolerance control in precision applications
• Right-hand thread direction, 0.255-inch shank diameter for standard toolholder compatibility
• Bright finish suitable for use with a variety of cutting fluids and lubricants

Compatibility

Designed for through-hole threading in alloy steel, aluminum, carbon steel, die steel, hardened steel, and stainless steel workpieces requiring a 1/4-28 UNF internal thread. Material application codes P and N apply per the OSG classification system.

Installation Notes

Thread forming taps require a properly sized forming hole, which is larger than a standard tap drill hole - consult OSG or standard thread forming drill charts for the correct pre-drill diameter before use. Always apply an appropriate tapping lubricant or cutting fluid for the workpiece material; dry forming is not recommended. Secure the workpiece and use a calibrated torque-controlled tapping machine or tap handle to prevent tap breakage. Inspect the tap for wear or chipping before each use and replace when torque values during forming increase noticeably.