Osg 1590300 Straight Flute Tap 1/4-28 Unf Plug Hss

Product Description

The OSG 1590300 is a straight flute tap designed for cutting right-hand internal threads in a range of ferrous and non-ferrous materials. Built from high-speed steel with a bright, uncoated finish, it produces 1/4-28 UNF threads using a plug chamfer style. The plug chamfer distributes cutting load across several leading threads, making it suitable for through-hole applications. With 4 flutes and an H11 thread limit, this tap holds close tolerances and runs true in standard tapping heads or hand tappers. Overall length is 2.5 inches, with a thread length of 1 inch and a shank diameter of 0.255 inches. It is sold as a single unit and is part of the OSG 101H series.

This tap is intended for use in production and maintenance environments where 1/4-28 UNF threads are required. The straight flute geometry works best in short-chipping materials and through-hole applications. Listed material applications include aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel. Machinists, tool-and-die workers, and maintenance technicians use this tap in drill presses, CNC machining centers, and hand tapping operations. It does not feature coolant-through capability, so flood or brush-applied cutting fluid is standard practice.

Key Features

• 1/4-28 UNF right-hand thread, 4-flute straight flute design for short-chipping materials
• Plug chamfer distributes cutting load across entry threads for controlled engagement in through-holes
• H11 thread limit for tight tolerance control and oversize compensation of 0.005 inches
• High-speed steel construction provides toughness across a range of workpiece materials
• Bright, uncoated finish compatible with a wide variety of cutting fluids
• Compact overall length of 2.5 inches with a 1-inch thread length for standard tapping clearances

Compatibility

Designed for use in through-hole tapping applications requiring 1/4-28 UNF right-hand threads. Suitable for aluminum, cast aluminum, cast iron, high-carbon steel, low-carbon steel, and medium-carbon steel workpieces as specified by the manufacturer.

Installation Notes

Installation is performed by machinists or maintenance technicians using standard tapping equipment or hand tools. Ensure the workpiece is securely fixtured and the tap is properly aligned before engagement to avoid tap breakage. Apply an appropriate cutting fluid for the workpiece material before and during tapping. Since this tap does not feature coolant-through capability, external lubrication must be maintained throughout the operation.