Spi 34-412-7 Plug Thread Gage 5/8-11 3B Double End

Product Description

The SPI 34-412-7 is a double-end plug thread gage designed to verify the accuracy of internal 5/8-11 UNC threads to a 3B tolerance class. One end carries the Go member, which must pass fully through an acceptable threaded hole, while the opposite No Go end must not enter a hole that conforms to spec. Machined from steel with NIST-traceable certification included, this gage gives machinists, quality technicians, and toolroom inspectors a fast, reliable method for in-process and final inspection of tapped holes without requiring a CMM or optical comparator.

This gage is suited to production and job-shop environments where 5/8-11 tapped holes appear in structural fastener applications, fixture plates, machine frames, and general mechanical assemblies. A size 3 handle is included, making the gage ready to use out of the box. The NIST traceability documentation supports ISO 9001 and AS9100 quality programs that require calibration records for inspection tooling. The double-end design consolidates Go and No Go checks into a single tool, reducing tool changes on the inspection bench.

Key Features

• Double-end design with Go and No Go members on a single gage body
• Checks 5/8-11 UNC internal threads to 3B tolerance class
• Steel construction for wear resistance during repeated use
• NIST-traceable certification included for quality system compliance
• Size 3 handle included — no additional purchase required

Compatibility

Designed for inspection of internal 5/8-11 UNC tapped holes manufactured to ANSI/ASME B1.1 3B thread class tolerances.

Installation Notes

Thread gages require no installation, but proper storage and handling directly affect accuracy. Keep the gage clean and lightly oiled when not in use to prevent corrosion on the precision-ground surfaces. Do not force the Go end through a hole — excessive torque will damage the gage and produce false readings. Periodic recalibration against NIST-traceable masters is required to maintain traceability documentation for accredited quality programs.