Spi 34-418-4 Plug Thread Gage 3/4-10 3B Double End

Product Description

The SPI 34-418-4 is a double-end plug thread gage used to verify the acceptance of internal 3/4-10 UNC threads to 3B tolerance class. One end carries the Go member; the opposite end carries the No Go member. Both ends must be applied during inspection: the Go end must pass fully through a conforming thread, and the No Go end must not enter. This gage is made from steel and ships with a size-3 handle already included. It is the standard tool used by machinists, quality inspectors, and manufacturing technicians to confirm threaded holes meet dimensional requirements before parts advance in production.

This gage is suited for inspecting 3/4-10 UNC internal threads in machined components across general manufacturing, maintenance, and fabrication environments. The 3B classification applies to general-purpose internal threads requiring a standard fit. A traceable NIST calibration certification is included, making this gage appropriate for use in quality systems that require documented traceability to national standards. Both production floor inspection and incoming material verification are common applications.

Key Features

• Double-end design combines Go and No Go gaging members in a single tool
• Calibrated to 3B tolerance class for 3/4-10 UNC internal threads
• Steel construction for durability and dimensional stability
• Size-3 handle included — no separate handle purchase required
• NIST traceability certification included for quality-system compliance

Compatibility

Designed for inspection of 3/4-10 UNC internal threads conforming to 3B tolerance class in machined parts and assemblies.

Installation Notes

Thread gages are inspection instruments, not cutting tools — never force the Go member through a thread or apply torque with a wrench. Apply the Go end by hand with light, even pressure; reject any part the Go end will not pass through completely. The No Go end should not enter the thread; if it does, the part is out of tolerance. Store gages in a protective case away from cutting fluids, abrasives, and temperature extremes to maintain calibration integrity.