Spi 29-313-4 Class Zz Plus Plug Gage 0.313 Inch

Product Description

The SPI 29-313-4 is a Class ZZ Plus plug gage designed for precision hole and bore measurement in machine shops, manufacturing facilities, and quality control environments. Built from steel, this go/no-go style gage checks whether a drilled, reamed, or bored hole falls within acceptable dimensional limits. The nominal measurement diameter is 0.313 inches with a tolerance of 0.0002 inches, making it suitable for applications where tight dimensional control is required. Machinists, toolmakers, and quality technicians use plug gages like this one to verify part conformance quickly and reliably without complex setup.

Class ZZ Plus plug gages are typically used in production inspection and incoming quality control for metalworking and fabrication operations. The 0.313-inch diameter covers a common hole size found in general machining work. This gage is appropriate for bench inspection stations, in-process checks at the machine, or final part verification before assembly. It is a single-unit item suited to both high-volume inspection lines and low-volume job shop environments.

Key Features

• 0.313-inch nominal measurement diameter for precise hole verification
• 0.0002-inch tolerance meets Class ZZ Plus gage accuracy requirements
• Steel construction provides durability and wear resistance in shop environments
• Compact and lightweight at 0.2 pounds for easy bench or in-process use

Compatibility

Designed as an OEM-style replacement or direct-use plug gage for inspection of 0.313-inch diameter holes in standard machining and manufacturing applications.

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 is clean and free of burrs or debris that could affect measurement accuracy. Do not force the gage into an undersized hole, as this can damage both the gage and the workpiece. Store in a protective case away from impact and temperature extremes to maintain calibration integrity.