Osg 1170202 Straight Flute Bottoming Tap 1/4-20 Unc Hss

Product Description

The OSG 1170202 is a straight flute bottoming tap designed for threading blind holes to near-full depth in a variety of metallic workpieces. It features a 1/4-20 UNC thread form with a 3B class of fit and H3 thread limit, making it suitable for applications that require consistent, close-tolerance internal threads. Constructed from high-speed steel, the tap delivers good wear resistance across a broad range of common shop materials. With 3 flutes and a bottoming chamfer, it cuts threads close to the bottom of a blind hole where spiral-point or plug taps cannot reach. Overall length is 2.5 inches with a thread length of 1 inch.

This tap is used in production and maintenance machining environments where 1/4-20 UNC internal threads are required in blind-hole applications. It is suited for use in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. Typical install scenarios include machine shops, toolrooms, and field repair operations. The right-hand thread direction and standard 1/4-20 UNC profile make it a direct fit for a wide range of fixtures, assemblies, and mechanical components requiring this common thread standard.

Key Features

• Bottoming chamfer allows threading to the bottom of blind holes
• 1/4-20 UNC thread form with 3B class of fit for standard tolerance internal threads
• H3 thread limit for consistent fit across production runs
• High-speed steel construction for durability across ferrous and non-ferrous materials
• 3 straight flutes for chip clearance in short-chipping materials
• Right-hand thread direction, no coolant-through requirement

Compatibility

Compatible with aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel workpieces. Designed for use in standard 1/4-20 UNC blind-hole tapping applications.

Installation Notes

This tap is installed by machinists and toolroom technicians using a tap wrench, tapping head, or CNC tapping cycle. Ensure the workpiece is securely fixtured and the tap is properly aligned with the pilot hole before engaging. Use an appropriate cutting fluid or tapping compound for the workpiece material to extend tap life and improve thread quality. Inspect the tap for wear or chipping before each use and replace if flute edges show damage.