Spi 34-342-6 Plug Thread Gage 1-72 3B Double End Go No Go

Product Description

The SPI 34-342-6 is a double-end plug thread gage designed to verify internal thread conformance to the 1-72 Unified National Fine (UNF) thread standard at a 3B tolerance class. One end checks the Go condition to confirm minimum material and proper thread form; the opposite end checks the No Go condition to confirm maximum material limits are not exceeded. The gage ships with a handle included and comes with a Traceability Certification traceable to NIST standards, making it ready for use in calibrated inspection environments. Weighing 1 pound, it is built from steel for durability under repeated gauge-room use.

This gage is suited for quality control inspections in precision machining, fastener manufacturing, aerospace component production, and any trade or industrial environment where threaded holes at the 1-72 size must meet Class 3B fit requirements. It is appropriate for use by machinists, quality technicians, and tool room professionals performing in-process or final inspection of small-diameter internal threads. The double-end design eliminates the need to handle two separate gages during a single inspection, improving workflow efficiency on the shop floor or inspection bench.

Key Features

• Double-end design with Go and No Go members on a single handle for streamlined inspection
• 1-72 thread size with Class 3B tolerance classification for tight-fit thread verification
• Steel construction for wear resistance and dimensional stability under regular use
• Handle included — no separate purchase required
• NIST Traceability Certification included for use in calibrated and documented inspection programs

Compatibility

Designed for inspection of internal threads conforming to the 1-72 Unified National Fine thread standard at Class 3B tolerance. Suitable for use wherever 1-72 UNF internal thread verification is required per NIST-referenced standards.

Installation Notes

Plug thread gages are used by quality technicians and machinists — not installed in a system, but handled in an inspection or tool room setting. Store the gage in its protective case when not in use to prevent nicks or corrosion that could affect accuracy. Clean threads and the gage members before each use; do not force the Go end through a thread that resists entry, as this can damage the gage or the workpiece. Periodic recalibration against NIST-traceable masters is recommended to maintain measurement integrity.