Spi 34-429-1 Double End Plug Thread Gage 1-8 2B Go No Go

Product Description

The SPI 34-429-1 is a double-end plug thread gage designed to verify 1-8 unified coarse (UNC) internal threads to a 2B class-of-fit tolerance. One end serves as the Go member and the other as the No Go member, allowing a single tool to confirm both the minimum and maximum acceptable thread form in one inspection sequence. The gage is made from steel and ships with a size 4 handle included. An NIST-traceable calibration certification is included, satisfying documentation requirements for quality systems and regulated manufacturing environments.

This plug thread gage is used in precision machining, fabrication, and industrial maintenance applications wherever 1-8 threaded holes must be inspected for conformance before assembly. The double-end format is common in production and incoming-inspection settings where speed and accuracy are both required. Machinists, quality technicians, and tool-room personnel use this type of gage to reject out-of-tolerance threads before parts advance in the workflow, reducing rework and assembly failures.

Key Features

• Double-end design: Go and No Go members on a single gage for complete 2B thread verification
• 1-8 thread size (UNC) — one of the most common coarse-thread standards in industrial fastening
• 2B class-of-fit tolerance for standard internal thread applications
• Steel construction for durability and dimensional stability under repeated use
• Size 4 handle included — ready to use out of the box
• NIST-traceable calibration certification included for quality and audit compliance

Compatibility

Designed for inspecting 1-8 UNC internal threaded holes conforming to 2B class-of-fit tolerances per NIST-referenced thread standards.

Installation Notes

Plug thread gages are hand-tools used by machinists and quality technicians — no power source or special tools are required for use. Handle the gage carefully to avoid nicks or burrs on the thread members, as contact damage will affect gage accuracy. Store the gage in its case and apply a light coat of rust-preventive oil when not in use. Periodic re-certification against NIST-traceable masters is recommended to maintain measurement integrity over time.