Osg 1626001908 Thread Forming Sti Tap 1/4-20 Unc H3

Product Description

The OSG 1626001908 is a thread forming STI tap designed for cutting internal threads in a wide range of metals. Unlike cutting taps, thread forming taps displace material rather than removing it, producing stronger threads with no chips to clear. This tap is configured for 1/4-20 UNC threads with an H3 thread limit and a semi-bottoming chamfer, making it suitable for applications where threading must reach close to the bottom of a blind hole. Manufactured from high-speed steel, it handles carbon steel, alloy steel, stainless steel, aluminum, nickel, titanium alloy, and hardened steel. The V finish provides a standard surface treatment appropriate for general-purpose tapping operations. Installation is performed by machinists and maintenance professionals using standard tapping equipment.

This tap is used in production and maintenance tapping applications across industrial, commercial, and repair environments. The semi-bottoming chamfer reduces the number of non-full threads at the bottom of a blind hole, making it a practical choice when thread engagement depth is a constraint. Its compatibility with a broad range of workpiece materials makes it a versatile addition to a tap set for general metalworking, machine maintenance, or fabrication work. The 1/4-20 UNC thread form is one of the most common fastener sizes in North American industrial and mechanical applications.

Key Features

• Thread forming design displaces material rather than cutting, producing stronger threads with no chip evacuation required
• Semi-bottoming chamfer allows threading close to the bottom of blind holes
• H3 thread limit ensures consistent class 3B fit for tight-tolerance applications
• High-speed steel construction supports use across carbon steel, alloy steel, stainless steel, aluminum, nickel, hardened steel, and titanium alloy
• V finish provides a standard surface treatment for general-purpose tapping
• Overall length of 3.5433 inches with a 1.125-inch thread length accommodates standard toolholding setups

Compatibility

Designed for tapping 1/4-20 UNC threads with a class 3B fit in carbon steel, alloy steel, stainless steel, aluminum, nickel, hardened steel, and titanium alloy workpieces.

Installation Notes

This tap should be installed in a tapping chuck, machine spindle, or hand tap wrench rated for the shank diameter. Ensure the workpiece is securely fixtured and the pilot hole is drilled to the correct diameter for thread forming before tapping. Apply appropriate cutting fluid for the workpiece material to reduce heat and extend tap life. Do not reverse the tap abruptly in blind holes, as thread forming taps require steady, controlled feed pressure.