Spi 29-557-6 Class Zz Plus Plug Gage 0.557 in Steel

Product Description

The SPI 29-557-6 is a Class ZZ Plus plug gage designed to inspect and verify bore diameters of 0.557 inches in production and quality-control environments. Built from steel, it delivers a working tolerance of 0.0002 inches, making it suitable for go/no-go verification tasks where dimensional accuracy is critical. Machinists, toolroom technicians, and quality inspectors use plug gages like this one to confirm that drilled, reamed, or bored holes fall within specified limits before parts move to the next stage of production. The Class ZZ Plus designation indicates a commercially accepted tolerance grade for general inspection work on non-precision to mid-precision applications.

This plug gage is used on the shop floor, in inspection rooms, and at incoming-inspection stations in manufacturing facilities. It is appropriate for checking steel, aluminum, plastic, and other workpiece materials when verifying a 0.557-inch nominal bore. Typical applications include production sampling, first-article inspection, and fixture verification. The single-piece package makes it straightforward to add to an existing gage set or to replace a worn member without purchasing a full kit.

Key Features

• 0.557-inch nominal diameter for direct bore verification
• 0.0002-inch working tolerance meets Class ZZ Plus grade requirements
• Steel construction provides durability and resistance to wear during repeated use
• Compact, lightweight design at 0.2 pounds for easy handling and storage
• Single-unit packaging allows targeted replacement of individual gage members

Compatibility

Designed as a standard Class ZZ Plus plug gage for use with any gage handle or gage-holding fixture that accepts a 0.557-inch member, consistent with common plug gage systems used in general manufacturing inspection.

Installation Notes

Plug gages should be handled with clean, dry hands or cotton gloves to prevent corrosion from skin oils. Before use, verify the gage and workpiece are at the same ambient temperature to avoid thermal expansion errors, particularly in precision environments. Apply light gage oil for storage and wipe clean before measuring. Inspection personnel should follow their facility calibration schedule and ASME B89.1.5 guidelines for gage care and handling.