Spi 34-396-2 Plug Thread Gage 7/16-20 3B Class Go No Go

Product Description

The SPI 34-396-2 is a double-end plug thread gage used to verify internal threads to a 7/16-20 specification at a 3B tolerance class. One end is ground to Go limits; the other to No Go limits. When the Go end passes freely and the No Go end is rejected by the threaded bore, the thread is confirmed within acceptable tolerance. The gage is made from steel and ships with a size 2 handle included. Traceability certification to NIST standards is included, making this gage suitable for documented quality-control programs. Machinists, quality inspectors, and toolroom technicians are the primary users.

This gage is applied wherever a 7/16-20 UNF internal thread must be verified for conformance — including production inspection, incoming parts verification, and repair or rework validation. The 3B classification covers the standard tolerance class used in most general-purpose inch fastener applications. The double-end design consolidates Go and No Go functions into a single tool, reducing the number of gages needed at the inspection station. Handle size 2 suits the thread diameter and provides a comfortable, consistent grip during use.

Key Features

• Double-end design with Go and No Go gages in one tool
• Thread size 7/16-20 UNF, 3B tolerance class
• Steel construction for durability in production and toolroom environments
• Size 2 handle included — no separate handle purchase required
• NIST traceability certification included for quality documentation and calibration records

Compatibility

Designed for inspection of 7/16-20 UNF internal threads at 3B tolerance class in standard inch-thread applications.

Installation Notes

Thread gages are inspection tools, not cutting tools — never force the Go end through a threaded bore or use power tools to drive the gage. Clean the threads and gage members before each use to prevent debris from causing false rejections. Handle the gage carefully and store it in its case when not in use to protect the ground surfaces. Periodic recalibration against NIST-traceable standards is recommended to maintain measurement integrity.