Spi 34-352-5 Plug Thread Gage 4-40 3B Double End Go No Go

Product Description

The SPI 34-352-5 is a double-end plug thread gage designed to inspect 4-40 unified coarse internal threads to ASME 3B tolerance class. One end carries the Go member; the opposite end carries the No Go member, allowing a technician to verify both minimum and maximum thread tolerance in a single tool. The gage is machined from steel for wear resistance and dimensional stability under repeated use. A handle is included. Traceability is backed by NIST certification, making this gage suitable for quality-control documentation in production and inspection environments.

This gage is used wherever 4-40 threaded holes must be verified for conformance to 3B class tolerances. Typical applications include incoming inspection of threaded fastener seats, in-process verification on CNC-machined components, and final inspection before assembly. The compact double-end format is well suited to bench inspection stations in machine shops, electronics manufacturing, aerospace sub-assembly, and precision instrument production. Any machinist, quality technician, or metrologist working to thread tolerance standards will find this tool appropriate for their workflow.

Key Features

• Double-end design combines Go and No Go members in one tool for efficient thread verification
• Calibrated to 4-40 thread size at ASME 3B tolerance class
• Steel construction provides durability and dimensional stability over extended use cycles
• NIST traceable certification included for quality-system documentation and audit compliance
• Handle included — ready to use out of the box with no additional accessories required

Compatibility

Designed for inspection of 4-40 unified coarse internal threads conforming to 3B class tolerances per ASME standards. Suitable for any threaded hole application requiring Go and No Go verification at this thread specification.

Installation Notes

Thread gages are inspection tools, not cutting tools — never force the Go member through a hole or apply torque to advance it past resistance. The Go member should pass through a conforming thread under hand pressure only; the No Go member should not enter a conforming thread. Clean and lightly oil the gage after each use to prevent corrosion. Store in a protective case away from impact hazards to preserve calibration.