Spi 34-279-0 Plug Thread Gage 7/16-14 No Go 3B

Product Description

The SPI 34-279-0 is a single-end No Go plug thread gage designed to verify that internal threads do not exceed maximum material condition limits. Built to 3B class tolerances, it checks 7/16-14 UNC threads and confirms the threaded feature will not accept an oversized or out-of-tolerance mating fastener. The gage body is machined from steel for durability and dimensional stability. A Size 2 handle is required for use but is sold separately. This tool is supplied with an NIST-traceable calibration certification, making it suitable for shop floor inspection, incoming quality control, and precision manufacturing environments.

This gage is used in manufacturing, machining, and assembly operations wherever 7/16-14 UNC internal threads must be verified to 3B class standards. Typical applications include aerospace, automotive, general metalworking, and mechanical assembly shops. The No Go member is used as the second step in a two-part thread inspection process: after a Go gage confirms minimum material acceptance, the No Go confirms the thread has not been cut oversize or damaged. Inspectors and machinists performing in-process or final inspection use this gage at the machine or on an inspection bench.

Key Features

• No Go plug gage checks 7/16-14 UNC threads for oversize or out-of-tolerance conditions
• 3B class tolerance for standard commercial and precision internal thread inspection
• Steel construction provides wear resistance and dimensional stability
• Single-end design with Size 2 handle interface
• Includes NIST-traceable traceability certification for quality documentation and audit compliance
• Conforms to NIST standards for thread gage calibration

Compatibility

Designed for inspecting 7/16-14 UNC internal threads to 3B class tolerance. Compatible with standard Size 2 plug gage handles, which are sold separately and not included with this gage.

Installation Notes

Thread gages are hand tools used by machinists and quality inspectors and do not require installation in a mechanical system. Store the gage in its protective case when not in use to prevent wear to the thread form. Do not apply power tools or excessive torque when using the gage in a threaded hole, as forced engagement can damage both the gage and the workpiece. Clean the gage and lightly oil it after use to prevent corrosion and maintain calibration integrity.