Spi 19-312-8 Class Zz Minus Plug Pin Gage 0.312 in

Product Description

The SPI 19-312-8 is a Class ZZ minus plug pin gage machined from steel, designed for go/no-go dimensional inspection of holes and bores at 0.312 inches nominal diameter. The minus designation indicates the gage is manufactured to the lower boundary of the tolerance band, following standard plug gage convention for go-side members. With a tolerance of 0.000200 inches, this gage delivers the measurement consistency required for quality control work in production and inspection environments. Machinists, tool-and-die technicians, and quality inspectors use pin gages like this to verify drilled, reamed, or bored hole diameters quickly and reliably without specialized metrology equipment.

Class ZZ plug pin gages are suited for general-purpose inspection work in machine shops, manufacturing facilities, and maintenance settings. This gage is appropriate for verifying hole size conformance in metal, plastic, or composite workpieces where a 0.312-inch diameter bore must be confirmed within specification. It is commonly used in both incoming inspection and in-process quality checks on production lines.

Key Features

• Class ZZ tolerance class for general-purpose hole inspection
• Minus designation for use as a go-side plug gage per standard convention
• 0.000200-inch tolerance for consistent, repeatable measurements
• Steel construction for durability in production environments
• Compact, single-piece design requires no calibration equipment for use

Compatibility

Designed as a general-purpose plug pin gage for inspecting holes and bores with a nominal diameter of 0.312 inches in standard Class ZZ inspection applications.

Installation Notes

Pin gages are a hand-tool inspection instrument and do not require installation. Handle with care to avoid dropping or surface contact that could damage the gage surface and affect accuracy. Store in a protective case when not in use to prevent corrosion and wear. Periodic cleaning and verification against a master reference gage is recommended to confirm continued accuracy.