Spi 34-403-6 Plug Thread Gage 1/2-28 2B Double End Go No Go

Product Description

The SPI 34-403-6 is a double-end plug thread gage used to verify the dimensional accuracy of internal 1/2-28 threads to the 2B tolerance class. One end carries the Go member and the other carries the No Go member, allowing a technician to confirm both the minimum and maximum material conditions in a single tool. A handle is included. The gage is made from steel and ships with an NIST-traceable traceability certification, making it suitable for use in quality-controlled environments where documented calibration traceability is required. Machinists, quality inspectors, and precision tool and die tradespeople are the primary users.

This gage is used wherever internal 1/2-28 threaded features must be accepted or rejected to 2B class limits. The 1/2-28 thread form is common in firearm barrels, precision instrumentation, and specialty hydraulic or pneumatic fittings. The double-end configuration reduces the number of individual gages needed at an inspection station and keeps the Go and No Go members paired to the same calibration certificate. The included handle is size 2, appropriate for the gage wire diameter associated with this thread size.

Key Features

• Double-end design combines Go and No Go members in one gage body
• Covers 1/2-28 thread size to 2B class tolerance
• Steel construction for durability and dimensional stability
• NIST-traceable traceability certification included for quality records
• Size 2 handle included — no separate handle purchase required

Compatibility

Designed for inspection of internal 1/2-28 2B class threaded features in any workpiece or assembly where that thread form is specified.

Installation Notes

Plug thread gages are used by quality inspectors and machinists, not installed in a system. Before use, clean the threaded bore and gage members of chips, oil, and debris to avoid false readings. Apply the Go member with hand pressure only — never force or use tools to drive the gage. If the Go member does not enter freely or the No Go member enters fully, the threaded feature is out of tolerance and should be rejected or reworked. Store the gage in its case when not in use to protect the thread form from damage.