Osg 1680900 Straight Flute Tap 1/2-28 Unef Plug Hss

Product Description

The OSG 1680900 is a straight flute plug tap designed for cutting 1/2-28 UNEF right-hand internal threads in a wide range of ferrous and non-ferrous materials. Built from high-speed steel with a bright uncoated finish, this 4-flute tap delivers reliable thread-cutting performance in through-hole and open-end applications. The plug chamfer - typically 3 to 5 threads of lead-in - provides a balanced starting action suited to general-purpose tapping on the shop floor or in the field. Overall length is 3.375 inches with a thread length of 1.154 inches, making it a standard-sized tool for 1/2-28 UNEF work.

This tap is engineered for use in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. It is well-suited to production and maintenance tapping operations where a standard straight-flute geometry is preferred for its rigidity and chip control in shorter chipping materials. The H3 thread limit designation makes it compatible with standard H3-tolerance threading work, which is common in general mechanical and automotive applications requiring the fine 28-threads-per-inch UNEF standard.

Key Features

• 1/2-28 UNEF thread size with 28 threads per inch for fine-pitch threading requirements
• Plug chamfer style with 4 flutes for balanced starting and chip evacuation in through-hole applications
• High-speed steel construction provides toughness across a broad range of workpiece materials
• Bright uncoated finish suitable for use with cutting fluids across compatible material types
• H3 thread limit for standard tolerance threading applications
• Right-hand thread direction; no coolant-through requirement simplifies setup

Compatibility

Rated for use in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. Part of the OSG Series 101N straight flute tap line.

Installation Notes

Installation is performed by machinists or maintenance technicians using a tap wrench, tapping head, or CNC machine spindle with appropriate tap holder. Always use a suitable cutting fluid or tapping compound for the workpiece material to reduce heat and extend tool life. Ensure the workpiece is securely fixtured and the tap is started square to the hole to prevent tap breakage. Follow shop safety procedures when handling sharp cutting tools.