Spi 34-254-3 No Go Plug Thread Gage 1/4-28 6H

Product Description

The SPI 34-254-3 is a single-end No Go plug thread gage designed to verify internal thread conformance to the 1/4-28 thread specification at 6H tolerance class. Manufactured from steel, this gage is used to confirm that a threaded hole does not accept an oversize condition, ensuring the mating fastener will fit within allowable tolerance limits. It conforms to ANSI standards and ships with NIST traceability certification, making it suitable for quality control environments where documented calibration is required. A size 1 handle is compatible but not included with this gage.

This plug thread gage is used in precision machining, manufacturing, and assembly inspection applications where internal thread quality must be verified before part acceptance. The No Go member of a Go/No Go gage set confirms upper tolerance compliance. It is appropriate for inspection of 1/4-28 UNF threaded holes in ferrous and non-ferrous components across aerospace, automotive, general manufacturing, and tool and die environments.

Key Features

• No Go plug gage checks that internal threads do not exceed maximum material condition
• 1/4-28 UNF thread size for fine-pitch internal thread inspection
• 6H tolerance class per ANSI standards for commercial and precision thread acceptance
• Steel construction for durability and dimensional stability
• NIST traceability certification included for quality system compliance
• Single-end design; accepts size 1 handle (sold separately)

Compatibility

Designed for use with a size 1 plug gage handle (not included). Intended for inspection of 1/4-28 UNF internal threads to ANSI 6H tolerance class specifications.

Installation Notes

Plug thread gages should be handled and stored carefully to prevent nicks, corrosion, or dimensional changes that could affect accuracy. Do not force the No Go gage into a threaded hole; a properly formed thread should resist full engagement. Gages should be periodically re-calibrated and inspected per your facility quality plan. Use appropriate thread gage oil when checking threaded holes to minimize wear on the gage member.