Osg 1165100 Straight Flute Tap 1/4-20 Unc Plug Hss

Product Description

The OSG 1165100 is a straight flute plug tap designed to cut 1/4-20 UNC internal threads in a wide range of ferrous and non-ferrous materials. Built from high-speed steel with a bright, uncoated finish, it delivers reliable thread-forming performance in through-hole and open-bottom applications where chip evacuation is straightforward. The plug chamfer - 3 to 5 threads of lead - makes it the standard choice for most general-purpose tapping operations. With 3 flutes, an overall length of 2.5 inches, and a thread length of 1 inch, this tap fits standard tap holders and hand-tapping setups used daily in machining and maintenance environments.

The OSG 1165100 is suited for production and maintenance tapping in materials including aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. It is used in machine shops, fabrication facilities, and field maintenance settings wherever 1/4-20 UNC threads are required. The H2 thread limit designation indicates a close tolerance fit, making it appropriate for standard fastener assemblies requiring consistent thread engagement.

Key Features

• 1/4-20 UNC thread form with H2 thread limit for close-tolerance thread production
• Plug chamfer provides 3 to 5 threads of lead for easy starting in through-hole applications
• High-speed steel construction handles aluminum, cast iron, and carbon steel workpieces
• Bright, uncoated finish suitable for use with standard cutting fluids
• 3 straight flutes promote chip clearance in open and through-hole applications
• Right-hand thread direction for use with standard tap holders and drivers

Compatibility

Designed for use in standard tap holders, T-handle wrenches, and CNC tapping chucks accepting a 0.255-inch shank diameter. Compatible with 1/4-20 UNC thread applications across aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel workpieces. No coolant-through capability; external cutting fluid or cutting paste is recommended.

Installation Notes

Tapping operations should be performed by a qualified machinist or maintenance technician familiar with cutting tool setup and speeds. Always secure the workpiece firmly and use a properly sized tap wrench or machine holder matched to the 0.255-inch shank. Apply appropriate cutting fluid for the workpiece material before and during tapping to extend tool life and improve thread finish. Back the tap out periodically to break chips and prevent tap breakage, especially in deeper holes.