Osg 1170102 Straight Flute Tap 1/4-20 Unc Hss Plug

Product Description

The OSG 1170102 is a straight flute tap designed for cutting 1/4-20 UNC internal threads in a wide range of ferrous and non-ferrous materials. Built from high-speed steel (HSS), this tap features a plug chamfer with 3 flutes, making it well-suited for through-hole and blind-hole applications where chips can be pushed ahead or cleared from the cut zone. It carries a 3B class of fit and an H3 thread limit, providing the tolerance control required for standard fastener fits in production and maintenance environments. The overall length is 2.5 inches with a 1-inch thread length. Right-hand thread direction. Machinists, toolroom technicians, and maintenance mechanics are the primary users.

This tap is intended for tapping operations in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The plug chamfer style - typically 3 to 5 threads of lead - makes it a versatile choice for starting in a hole that has been drilled to the correct tap drill size. It is appropriate for both manual hand-tapping and machine tapping setups in job shop, production, and field maintenance contexts. The OSG Series 103 designation identifies the product line within the OSG tap catalog.

Key Features

• 1/4-20 UNC right-hand thread, 3B class of fit with H3 thread limit for standard tolerance fastener applications
• High-speed steel construction provides durability across a broad range of workpiece materials
• 3-flute straight flute geometry suitable for through-hole and blind-hole tapping
• Plug chamfer (approximately 3-5 thread lead) allows easy starting and consistent thread engagement
• Compatible with aluminum, cast iron, low-, medium-, and high-carbon steel workpieces
• No coolant-through requirement - compatible with flood, mist, or dry tapping setups

Compatibility

Designed for use in any machine or hand-tapping application requiring a 1/4-20 UNC thread form. Fits standard tap holders and collets sized for 1/4-20 taps. Suitable for aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel per OSG material application data.

Installation Notes

Ensure the workpiece is drilled to the correct tap drill diameter for 1/4-20 UNC before starting. Secure the tap in a properly aligned tap holder or tap wrench to prevent thread misalignment and tap breakage. Apply appropriate cutting fluid for the workpiece material - cutting oil for steels, light oil or kerosene for aluminum. Reverse the tap periodically during hand tapping to break and clear chips, especially in blind holes.