Spi 34-273-3 Plug Thread Gage 3/8-24 6H No Go

Product Description

The SPI 34-273-3 is a single-end No Go plug thread gage used to verify internal thread dimensions to the 3/8-24 UNF thread specification. Made from steel, it checks that a threaded hole does not accept an oversized or out-of-tolerance thread form, ensuring the workpiece meets the 6H tolerance class. The gage ships without a handle; a Size 2 handle is required for use and must be sourced separately. It is calibrated to ANSI and NIST standards and includes a traceability certification to NIST, making it suitable for documented quality-control workflows on the shop floor or in the field.

This No Go plug thread gage is used in manufacturing, machining, and mechanical assembly environments where 3/8-24 UNF internal threads must be verified against tolerance class 6H. It is appropriate for incoming inspection, in-process quality checks, and final acceptance testing. Trades and disciplines that rely on fine unified threads in precision assemblies — including HVAC equipment manufacturing, instrumentation, and mechanical contracting — will find this gage useful wherever thread conformance documentation is required.

Key Features

• No Go single-end design confirms threads do not exceed 6H tolerance limits
• 3/8-24 UNF thread size for fine-pitch internal thread inspection
• Steel construction for durability in production and inspection environments
• Calibrated to ANSI and NIST standards with traceability certification included
• Accepts a Size 2 handle (sold separately) for standard gage-handle compatibility

Compatibility

Designed for use with a standard Size 2 plug thread gage handle (not included). Suitable for inspecting any 3/8-24 UNF internal thread requiring 6H class conformance per ANSI standards.

Installation Notes

Thread gages are precision tools and should be handled and stored carefully to prevent damage to the gauging surface. A Size 2 handle must be attached before use; do not attempt to rotate the gage without a proper handle, as this can damage the gage member or cause inaccurate readings. Clean threads of chips, debris, and cutting fluid before gauging. Follow your facility quality plan and applicable ANSI B1 series standards for proper thread gage usage and calibration intervals.