Spi 34-425-9 Plug Thread Gage 7/8-14 2B Double End

Product Description

The SPI 34-425-9 is a double-end plug thread gage used to verify internal thread conformance to the 7/8-14 UNF thread form at 2B tolerance class. One end carries the Go member and the opposite end carries the No Go member, allowing a technician to confirm both minimum and maximum material condition in a single tool. The gage is constructed of steel and ships with a size 4 handle included. A NIST-traceable calibration certificate is included, supporting quality-system documentation requirements in manufacturing, machining, and inspection environments.

This gage is suited for incoming inspection, in-process thread verification, and final QC checks on tapped holes or threaded components with a 7/8-14 internal thread. It is commonly used in precision machining shops, aerospace component production, hydraulic fitting inspection, and general metalworking environments where thread acceptance criteria must be documented and traceable to a national standard.

Key Features

• Double-end design combines Go and No Go members in one tool for efficient inspection
• 7/8-14 thread size with 2B tolerance class per unified thread standards
• Steel construction for durability in production and inspection settings
• Size 4 handle included — no separate handle purchase required
• NIST-traceable certification included to support ISO and quality-system compliance

Compatibility

Designed to inspect internal threads conforming to the 7/8-14 UNF 2B thread specification. Suitable for use with any tapped hole or threaded component produced to that thread form and tolerance class.

Installation Notes

Thread plug gages are used by machinists, quality inspectors, and toolroom technicians — no installation in the field sense applies, but proper gage handling is critical to accuracy. Always clean threads and the gage members thoroughly before use to remove chips, coolant, or debris that could cause false readings. Apply light, consistent hand pressure only — never force a Go or No Go member with a wrench or power tool. Store the gage in its case when not in use and recalibrate on a schedule consistent with your quality management system requirements.