Spi 34-386-3 Plug Thread Gage 5/16-32 3B Class Go No Go

Product Description

The SPI 34-386-3 is a double-end plug thread gage designed to verify internal thread quality on 5/16-32 threaded features. One end carries the Go member, which confirms that the thread form, pitch diameter, and lead fall within acceptable limits. The opposite end carries the No Go member, which confirms the pitch diameter has not been cut oversize. The gage is constructed of steel for wear resistance and dimensional stability under repeated use. A handle is included. A NIST-traceable calibration certificate ships with the gage, supporting documentation requirements for quality management systems and inspection records.

This gage is suited for production floor inspection, incoming inspection, and tool room verification wherever 5/16-32 unified inch threads must be held to a 3B tolerance class. The 3B classification applies to general-purpose internal threads with a standard allowance, making this gage appropriate for nuts, tapped holes in assemblies, and any fastened joint requiring controlled fit. Machinists, quality technicians, and tool-room personnel are the primary users. The included handle size 1 is matched to the gage diameter for comfortable single-hand operation during high-volume inspection.

Key Features

• Double-end design puts Go and No Go members on a single handle for efficient pass-fail inspection
• 5/16-32 thread size with 3B tolerance class for general-purpose internal thread verification
• Steel construction for durability and dimensional stability across repeated use cycles
• NIST-traceable traceability certification included for quality system documentation
• Handle size 1 included — no additional tooling required out of the box

Compatibility

Designed for inspection of 5/16-32 unified inch internal threads held to ANSI/ASME 3B tolerance class. Use wherever tapped holes or threaded components must be verified against that specification.

Installation Notes

Thread plug gages are hand tools used by quality technicians and machinists — no power equipment is required. The Go member should pass fully through a conforming thread under hand force only; forced engagement can damage gage members and invalidate results. The No Go member should not enter more than two turns on a conforming thread. Store gages in a protective case away from moisture and temperature extremes to maintain calibration integrity, and re-certify on a schedule appropriate to your quality management system.