Spi 34-350-9 Plug Thread Gage 3-56 3B Double End Go No Go

Product Description

The SPI 34-350-9 is a double-end plug thread gage designed to inspect 3-56 UNC threaded holes to Class 3B tolerances. One end carries the Go member and the other carries the No Go member, allowing a technician to verify both the minimum and maximum allowable thread form in a single tool. The gage ships with a handle included and comes with NIST traceability certification, satisfying documentation requirements for calibrated inspection tooling in quality-controlled environments. Construction is steel for durability under repeated shop-floor use.

This gage is used wherever 3-56 threaded holes must be inspected to a Class 3B fit standard. Typical applications include precision machining shops, assembly lines, and quality control departments working with small-fastener components in electronics, instrumentation, or light mechanical assemblies. The compact size suits inspection of tapped holes in sheet metal, housings, and miniature hardware. NIST traceability documentation makes it suitable for AS9100, ISO 9001, and similar quality system audit requirements.

Key Features

• Double-end design combines Go and No Go members in one gage for efficient hole inspection
• Class 3B tolerance classification for tight-fit thread verification
• NIST traceability certification included for quality system compliance
• Handle included — ready to use out of the box
• Steel construction for wear resistance under repeated use

Compatibility

Designed for inspection of 3-56 UNC threaded holes manufactured to Class 3B tolerance specifications. Compatible with standard plug gage handles of the appropriate handle size for this gage series.

Installation Notes

Thread plug gages are inspection tools, not cutting tools — never force the Go end through a hole or use power tools to drive the gage. Insert the Go end by hand with light, steady pressure; a properly formed hole should accept the Go end fully and reject the No Go end. Store the gage in its protective case when not in use to prevent damage to the thread form. Periodic recalibration against NIST-traceable masters is recommended per your facility quality plan.