Spi 34-372-3 Plug Thread Gage 12-24 3B Class Go No Go

Product Description

The SPI 34-372-3 is a double-end plug thread gage designed to inspect 12-24 unified coarse internal threads to the 3B tolerance class. One end carries the Go member and the other carries the No Go member, allowing a technician to verify both the minimum and maximum thread tolerance boundaries in a single tool. The gage is manufactured from steel and ships with a handle included. A NIST-traceable certification is included with each unit, satisfying documentation requirements for quality-controlled manufacturing and inspection environments. This tool is used by machinists, quality control inspectors, and precision assembly technicians.

This gage is suited for production and inspection work wherever 12-24 threaded holes must be verified against ASME B1.2 Go/No Go acceptance criteria. Typical applications include inspection of tapped holes in fabricated assemblies, machined components, and manufactured hardware where thread fit and engagement must meet 3B class tolerances. The double-end design keeps both members on one handle, reducing tool changeover time during high-volume inspection runs.

Key Features

• Double-end design with Go and No Go members on a single handle
• Inspects 12-24 unified coarse internal threads to 3B class tolerance
• Steel construction for durability and dimensional stability
• Handle included — ready to use out of the package
• NIST-traceable calibration certificate included for quality documentation

Compatibility

Designed for inspection of 12-24 unified coarse internal threaded features held to ASME 3B class tolerances.

Installation Notes

Thread gages are used by machinists and quality inspectors — no power shutdown is required for use. Insert the Go member into the threaded hole with light hand pressure only; never force a thread gage, as doing so can damage gage members and produce false readings. The No Go member should not enter the threaded hole; if it does, the hole is out of tolerance. Store the gage in its case and keep it clean and lightly oiled to maintain calibration integrity.