Spi 29-555-0 Class Zz Plus Plug Gage 0.555 Inch

Product Description

The SPI 29-555-0 is a Class ZZ Plus plug gage machined to a 0.555-inch nominal diameter with a tolerance of 0.0002 inches. Plug gages are single-purpose precision inspection tools used to verify whether a drilled, bored, or reamed hole falls within an acceptable dimensional range. The Class ZZ Plus designation indicates a commercial-grade tolerance class suited for production floor inspection and incoming quality control checks. Constructed from steel, the 29-555-0 provides the wear resistance and dimensional stability required for repeatable go/no-go measurement in manufacturing and machining environments. Machinists, quality technicians, and tool-room inspectors are the primary users of this gage.

This plug gage is used in production inspection settings where hole diameter conformance must be verified quickly and reliably. It is well suited for checking holes in machined components, castings, forgings, and fabricated assemblies. The 0.555-inch diameter makes it appropriate for applications involving standard fractional and close-decimal bore sizes in both light manufacturing and precision machine shop work. Its compact size and low weight make it easy to handle during high-volume inspection cycles.

Key Features

• 0.555-inch nominal diameter for direct hole-size verification
• Class ZZ Plus tolerance of 0.0002 inches for commercial-grade inspection accuracy
• Steel construction for wear resistance and dimensional stability
• Compact and lightweight at 0.2 pounds for easy single-hand use
• Go/no-go inspection without the need for measurement instruments or readouts

Compatibility

Designed as a standard plug gage for inspecting holes with a nominal diameter of 0.555 inches in machined parts, castings, and fabricated components across general manufacturing and tool-room applications.

Installation Notes

Plug gages are used by quality technicians and machinists and require no installation in the traditional sense, but proper handling is essential for accurate results. Always clean the gage and the workpiece hole before use to remove chips, coolant, and debris that can affect readings. Do not force the gage into an undersized hole, as this can damage the gage land and compromise dimensional accuracy. Store the gage in a protective case away from impact hazards and temperature extremes to maintain calibration integrity.