Osg 1122500 Straight Flute Tap 1/2-13 Unc Plug 3B Hss

Product Description

The OSG 1122500 is a straight flute tap designed to cut 1/2-13 UNC internal threads in a wide range of ferrous and non-ferrous metals. Built from high-speed steel with a bright, uncoated finish, it features a plug chamfer for general-purpose through-hole and blind-hole tapping. With 4 flutes and an H3 thread limit, this tap produces accurate 3B class of fit threads suitable for standard fastener assemblies. Overall length is 3.375 inches, thread length is 1.656 inches, and the shank diameter is 0.367 inches. It is intended for use in manual tapping handles, drill presses, and CNC tapping operations where a straight flute geometry is appropriate for the material and application.

This tap is suited for production and maintenance tapping in aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel. The plug chamfer makes it a practical choice for starting threads in through-holes or sufficiently deep blind holes where the chamfer lead can fully engage before reaching the bottom. It fits standard tap holder collets that accept the 0.367-inch shank diameter and 0.275-inch square drive. Typical use cases include fabrication shops, machine shops, and field maintenance where 1/2-13 UNC threads are required in structural and mechanical assemblies.

Key Features

• 1/2-13 UNC thread form with 4 straight flutes for general-purpose through-hole and blind-hole tapping
• Plug chamfer provides a gradual thread lead-in, reducing starting torque and improving alignment
• H3 thread limit and 3B class of fit for standard fastener clearance and accurate thread geometry
• High-speed steel construction provides durability across a broad range of common workpiece materials
• Bright, uncoated finish is compatible with standard cutting fluids and tapping compounds
• Right-hand thread direction; no coolant-through feature, suitable for flood or manual lubrication

Compatibility

Designed as a standard replacement or production tap for applications requiring 1/2-13 UNC, 3B class of fit internal threads. Compatible with material types including aluminum, cast aluminum, cast iron, low-carbon steel, medium-carbon steel, and high-carbon steel per OSG Series 101 specifications.

Installation Notes

Install in a properly sized tap wrench, tapping head, or rigid CNC tap holder that matches the 0.275-inch square drive. Secure the workpiece and apply an appropriate cutting fluid or tapping compound for the material being tapped before beginning the operation. Back the tap off periodically to break chips and prevent tap breakage, especially in blind holes. Follow shop safety procedures and wear appropriate eye protection whenever performing tapping operations.