Spi 29-327-4 Class Zz Plus Plug Gage 0.327 in

Product Description

The SPI 29-327-4 is a Class ZZ Plus plug gage machined to a 0.327-inch nominal diameter with a tolerance of 0.0002 inches. Plug gages are precision go/no-go inspection tools used to verify that a bored hole or internal feature meets its dimensional specification. This gage is constructed from steel for wear resistance and dimensional stability. It is used in production inspection, incoming quality control, and toolroom environments wherever tight-tolerance hole verification is required. Machinists, quality technicians, and tool-and-die professionals are the primary users of this type of instrument.

The 29-327-4 is suited for inspecting drilled, reamed, or bored holes held to close tolerances in precision machined components. Class ZZ Plus gages are appropriate for general-purpose production inspection where a verified, traceable tolerance is required. The 0.327-inch diameter covers a common decimal-inch hole size found in mechanical assemblies, jigs, and fixtures across metalworking and fabrication environments.

Key Features

• Class ZZ Plus tolerance class provides a verified 0.0002-inch tolerance for reliable go/no-go inspection
• 0.327-inch nominal diameter targets a precise decimal-inch hole specification
• Steel construction delivers hardness and dimensional stability under repeated use
• Compact, single-piece form integrates directly into standard plug gage handle systems
• Lightweight at 0.2 pounds, suited for bench or in-line inspection use

Compatibility

Designed as an OEM-style replacement or direct-use plug gage member compatible with standard plug gage handles accepting 0.327-inch diameter gage members in Class ZZ Plus tolerance class.

Installation Notes

Plug gages should be inserted and removed by hand without forcing — never strike or press-fit a plug gage into a hole. Keep the gage clean and lightly oiled when stored to prevent corrosion on the steel surface. Periodic calibration against a traceable standard is recommended to confirm the gage remains within its stated tolerance class. Handle only by the body or a properly fitted gage handle to avoid introducing thermal expansion error from hand heat.