Spi 23-137-3 Threaded Ring Gage 6-40 Class 2A Go No Go

Product Description

The SPI 23-137-3 is a double-ring threaded ring gage designed to inspect external threads to the 6-40 Unified National thread standard at Class 2A tolerances. It includes both a Go ring and a No Go ring in a single double-ring configuration, allowing technicians to verify that male-threaded fasteners and components fall within the specified tolerance range in one efficient step. Constructed from tool steel for durability and dimensional stability, this gage ships with NIST traceability certification, supporting quality assurance and calibration documentation requirements in precision manufacturing and inspection environments.

This gage is used in machine shops, precision manufacturing facilities, quality control labs, and production environments where 6-40 threaded components must be verified against Class 2A fit specifications. It is appropriate for inspecting small-diameter fasteners, machine screws, and threaded inserts common in electronics, instrumentation, and light mechanical assemblies. The NIST traceability certificate makes it suitable for controlled inspection processes and audited quality systems.

Key Features

• Go and No Go rings in a single double-ring body for complete Class 2A thread inspection
• Thread size: 6-40 Unified National thread form
• Class 2A tolerance classification for standard external thread inspection
• Tool steel construction for long service life and dimensional stability
• Includes NIST traceability certification for calibration and quality documentation
• Compact and lightweight at 0.118 pounds for easy bench use

Compatibility

Designed for inspection of external 6-40 Unified National threads machined to Class 2A tolerances, including machine screws, threaded fasteners, and small-diameter threaded components in that thread form and classification.

Installation Notes

Thread ring gages are used by quality control inspectors and machinists and require no installation in the traditional sense. Store gages in a clean, dry environment and handle with care to avoid nicks or contamination that could affect accuracy. Clean threads on both the gage and the workpiece before inspection. Periodic recalibration against NIST-traceable standards is recommended to maintain measurement integrity.