Spi 29-120-3 Class Zz Plus Plug Gage 0.12 in Steel

Product Description

The SPI 29-120-3 is a Class ZZ Plus plug gage designed to verify the dimensional accuracy of drilled, bored, or reamed holes with a nominal diameter of 0.12 inches. Built from steel, this fixed-limit gage provides a straightforward go/no-go inspection method used in precision machining, manufacturing, and quality control environments. The 29-120-3 carries a tolerance of 0.0002 inches, which meets Class ZZ Plus standards for general-purpose inspection where tight dimensional verification is required. Machinists, toolmakers, and quality technicians rely on plug gages like this one to confirm hole sizes quickly and consistently without the need for calibrated measuring instruments on every check.

This plug gage is suited for use in machine shops, production facilities, and inspection departments where small-diameter hole verification is a routine part of the manufacturing process. It is appropriate for both batch inspection and in-process quality checks on parts produced to close tolerances. The 0.12-inch diameter range targets small precision holes common in mechanical assemblies, tooling fixtures, and tight-tolerance components. Quality control personnel and CNC machinists are the primary users in light industrial and precision manufacturing settings.

Key Features

• Class ZZ Plus tolerance rating at 0.0002 inches for reliable go/no-go inspection
• Steel construction for durability and dimensional stability under shop conditions
• 0.12-inch nominal measurement diameter targets small precision holes
• Fixed-limit design enables fast, repeatable hole-size verification without setup
• Compact and lightweight at 0.2 pounds for easy handling at the inspection station

Compatibility

Designed as an OEM-style fixed-limit inspection tool for verifying 0.12-inch diameter holes in general-purpose precision machining and quality control applications.

Installation Notes

Plug gages are handled and used by machinists and quality control technicians rather than installed in a mechanical system. Clean the gage and the part bore before use to prevent debris from affecting the measurement. Store the gage in its protective case when not in use to prevent surface damage that could alter the tolerance reading. Verify gage calibration status periodically in accordance with your facility quality management procedures.