Osg 1121305 Straight Flute Tap 3/8-16 Unc Hss Tin

Product Description

The OSG 1121305 is a straight flute hand tap designed for cutting internal threads in a wide range of ferrous and non-ferrous materials. Built from high-speed steel (HSS) with a titanium nitride (TiN) coating, this tap delivers extended tool life and reduced friction during threading operations. It cuts a 3/8-16 UNC thread profile to a 3B class of fit with an H3 thread limit, making it suitable for precision fastener applications where tolerance control matters. The plug chamfer provides a gradual lead-in over several threads, suited for through-hole tapping. Overall length is 2-15/16 inches with a 1-1/4 inch thread length and a four-flute design for balanced chip evacuation.

This tap is intended for hand tapping or machine tapping operations in through-hole and open-bottom blind-hole applications across light manufacturing, maintenance, repair, and overhaul (MRO) environments. Compatible material applications include aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. It is well-suited for machinists, millwrights, and maintenance technicians working in industrial, HVAC fabrication, plumbing rough-in, and general mechanical assembly settings where 3/8-16 UNC threaded holes are required.

Key Features

• HSS construction with TiN coating for extended wear resistance and reduced cutting friction
• 3/8-16 UNC thread form, 3B class of fit, H3 thread limit for controlled tolerance threading
• Plug chamfer (3-5 thread lead-in) suitable for through-hole tapping applications
• Four-flute straight design promotes balanced cutting forces and chip evacuation
• Right-hand thread direction for standard fastener compatibility
• Rated for aluminum, cast iron, low-, medium-, and high-carbon steel material applications

Compatibility

Designed as an OEM-style replacement and standard production tap for applications requiring a 3/8-16 UNC internal thread in aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel workpieces.

Installation Notes

Installation should be performed by qualified machinists or maintenance technicians familiar with tapping procedures and appropriate cutting fluid selection for the workpiece material. Ensure the workpiece is securely fixtured and the pilot hole is drilled to the correct tap drill diameter before threading. Always use a cutting lubricant appropriate for the workpiece material to maximize tool life and thread quality. De-energize and lock out any powered tapping equipment before changing or inspecting the tap.