Spi 34-387-1 Plug Thread Gage 3/8-16 2B Double End

Product Description

The SPI 34-387-1 is a double-end plug thread gage used to verify the accuracy of internal 3/8-16 UNC threads to the 2B tolerance class. One end carries the Go member and the opposite end carries the No Go member, allowing a technician to confirm both minimum and maximum thread acceptance in a single tool. The gage is manufactured from steel and ships with a size 2 handle included. A NIST-traceable calibration certificate is included, making this gage suitable for use in quality-controlled production and inspection environments. Machinists, toolroom technicians, and quality control inspectors use this gage as part of standard thread-inspection protocol.

This gage applies wherever 3/8-16 internal threads must be verified to ANSI 2B standards. Typical applications include incoming inspection of threaded fastener holes, in-process verification on CNC and manual machining operations, and final inspection before assembly. The double-end design reduces the number of tools required at the inspection station and speeds the go/no-go decision. The included handle is sized to match the gage members, providing consistent grip and feel during inspection cycles.

Key Features

• Go and No Go members on a single double-end gage — complete 2B thread inspection in one tool
• 3/8-16 UNC thread size with 2B tolerance classification
• Steel construction for durability in shop environments
• Size 2 handle included — no separate handle purchase required
• NIST-traceable traceability certification included for quality system documentation
• Meets NIST standards for dimensional inspection

Compatibility

Designed for inspection of internal 3/8-16 UNC threads held to the 2B tolerance class in accordance with ANSI unified thread standards.

Installation Notes

Thread gages are inspection instruments, not cutting tools — never force the Go member through a thread or apply rotational torque beyond hand pressure. The No Go member should not enter the threaded hole by more than two turns; entry beyond that indicates the thread is out of tolerance. Handle the gage carefully to avoid nicks or corrosion that could affect calibration. Store in the provided case or a protected location, and re-certify on a schedule consistent with your quality management system requirements.