Spi 34-268-3 Plug Thread Gage 3/8-16 6H Single End Go

Product Description

The SPI 34-268-3 is a single-end Go plug thread gage designed to verify the minimum material condition of internal 3/8-16 UNC threads to 6H tolerance class. Manufactured from steel, this gage checks that a threaded hole has been cut to the correct pitch diameter so a mating fastener will engage properly. It is sized for a Size 2 handle, which is sold separately. A NIST-traceable calibration certificate is included, supporting quality-system documentation requirements in manufacturing, maintenance, and inspection environments. Machinists, quality technicians, and toolroom specialists use this gage as part of a go/no-go inspection routine to confirm thread conformance before assembly.

This gage is applied wherever 3/8-16 internal threads must be verified against ANSI and NIST standards. Typical applications include incoming inspection of threaded components, in-process thread verification on CNC and manual machining operations, and final quality checks in production or MRO settings. The 6H classification makes it appropriate for general-purpose commercial thread fits. It is used across industries including HVAC equipment manufacturing, mechanical assembly, and industrial maintenance.

Key Features

• Go member checks minimum material condition of 3/8-16 UNC internal threads
• 6H tolerance class for standard commercial thread fit verification
• Steel construction for durability in shop and inspection environments
• NIST-traceable calibration certificate included for quality-system compliance
• Conforms to ANSI and NIST standards
• Single-end design accepts a Size 2 handle (handle not included)

Compatibility

Designed for use with standard Size 2 plug gage handles. Suitable for inspecting any 3/8-16 UNC internal thread to 6H tolerance class per ANSI standards.

Installation Notes

This gage is used by quality technicians and machinists and does not require installation in the traditional sense. Before use, ensure the threaded hole is clean and free of chips or debris that could damage the gage member. Insert the Go member by hand without forcing; a conforming thread should accept the Go gage with light hand pressure. Handle the gage carefully to avoid drops or impacts that can alter calibration, and store it in a protective case when not in use.