Spi 29-420-7 Class Zz Plus Plug Gage 0.42 in Dia

Product Description

The SPI 29-420-7 is a Class ZZ Plus plug gage designed for precision hole diameter verification in production and inspection environments. It measures a nominal bore diameter of 0.42 inches with a tolerance of 0.0002 inches, meeting the requirements of Class ZZ Plus accuracy standards. Constructed from steel for durability and dimensional stability, this plug gage provides a reliable go/no-go reference for quality control checks. Machinists, toolmakers, and quality technicians use plug gages like this to confirm that drilled, reamed, or bored holes fall within specified tolerances before parts move to the next stage of production.

This gage is suited for use on shop floors, in inspection rooms, and at receiving inspection stations where consistent hole diameter verification is required. It is appropriate for both low-volume prototype work and higher-volume production runs where tight tolerances must be confirmed quickly and without complex setup. The 0.42-inch diameter range fits a common fastener and bore size used across general metalworking, mechanical assembly, and machining operations.

Key Features

• Nominal measurement diameter of 0.42 inches for a common bore size
• Class ZZ Plus tolerance of 0.0002 inches for precise go/no-go inspection
• Steel construction provides wear resistance and long-term dimensional stability
• Compact and lightweight at 0.2 pounds for easy single-handed use
• Single-piece package quantity supports individual tooling purchases

Compatibility

Designed as a standard Class ZZ Plus plug gage for verifying 0.42-inch nominal bore diameters in general machining and inspection applications. Suitable for use with any workpiece or fixture requiring go/no-go hole diameter verification at this size.

Installation Notes

Plug gages are handled and used by machinists, toolmakers, and quality control inspectors. Ensure the workpiece is clean and free of chips or coolant before gaging to avoid false readings or gage wear. Store the gage in a protective case or rack when not in use to prevent surface damage. Calibration and use should follow shop metrology procedures and applicable ASME B89 standards for gage accuracy and maintenance.