Spi 19-328-4 Class Zz Minus Plug Pin Gage 0.328 in

Product Description

The SPI 19-328-4 is a Class ZZ minus plug pin gage machined from steel and sized at 0.328 inches in diameter. It is used to verify that a hole, bore, or opening meets a specified minimum diameter by confirming the gage passes through the feature. Class ZZ is the standard tolerance grade for general-purpose inspection of production parts. The minus designation means the gage is ground to the low side of the nominal diameter, which is the correct approach for a go-type functional check. Tolerance on this gage is 0.0002 inches, making it suitable for moderate-precision inspection work in a shop or receiving environment.

This gage is applied wherever a machinist, quality technician, or tool-and-die professional needs to verify hole size on machined components, castings, or fabricated parts. It is a common tool on the inspection bench in manufacturing shops, job shops, and maintenance facilities. The 0.328-inch size fits a range of drilled and reamed holes encountered in general mechanical assembly. It is used as a standalone check or as part of a set of pin gages covering a size range.

Key Features

• Class ZZ tolerance grade for general-purpose production inspection
• Minus designation confirms go-side functional hole checking
• 0.0002 inch tolerance for consistent, repeatable measurement
• Steel construction for durability and dimensional stability
• 0.328 inch nominal diameter covers a common drilled and reamed hole size

Compatibility

Designed as a standard pin gage for use with any pin gage handle or holder accepting the 0.328-inch diameter shank, and compatible with Class ZZ inspection procedures for general-purpose hole verification.

Installation Notes

Pin gages are handled and stored with care to prevent nicks, corrosion, or thermal distortion that would affect accuracy. Clean the gage and the feature under inspection before use. Never force a pin gage through a hole; if resistance is felt, the hole is undersize or contains debris. Gages should be recalibrated periodically in accordance with your facility quality system requirements.