Spi 23-191-0 Threaded Ring Gage 5/8-24 Unef Class 2A

Product Description

The SPI 23-191-0 is a double-ring threaded ring gage used to verify the dimensional accuracy of externally threaded fasteners and components cut to a 5/8-24 UNEF thread form. This set includes both a Go ring and a No Go ring in a single unit, allowing technicians to confirm that a threaded part falls within the acceptable tolerance band for Class 2A fit. Manufactured from tool steel, the gage provides the hardness and wear resistance required for repeated use in production and inspection environments. Calibrated to NIST-traceable standards, it is suited for quality control, incoming inspection, and shop-floor thread verification.

This gage is used wherever 5/8-24 UNEF external threads must be verified to Class 2A tolerance — a fit classification common in aerospace, firearms, precision mechanical assemblies, and instrumentation components. The Go ring confirms that the thread is not undersized or misformed, while the No Go ring confirms the thread is not oversized. Both functions are contained in one double-ring body, reducing the number of individual tools required at an inspection station. Machinists, quality technicians, and toolroom personnel are the primary users.

Key Features

• Go and No Go rings combined in a single double-ring gage body
• Thread size: 5/8-24 UNEF for external thread inspection
• Class 2A tolerance classification for standard-fit external threads
• Tool steel construction for durability and long service life
• Calibrated to NIST-traceable standards for traceable inspection records

Compatibility

Designed for inspection of externally threaded workpieces with a 5/8-24 UNEF thread form manufactured to Class 2A tolerance specifications.

Installation Notes

Threaded ring gages are handled and stored by quality technicians and toolroom personnel, not installed in a system. Keep the gage clean and lightly oiled when not in use to prevent corrosion on the tool steel surfaces. Do not force the gage onto a thread — excessive resistance on the Go ring indicates the thread is out of tolerance and should be evaluated before proceeding. Periodic re-calibration against NIST-traceable masters is recommended to maintain inspection integrity.