Spi 19-668-3 Class Zz Minus Plug Pin Gage 0.668 in

Product Description

The SPI 19-668-3 is a Class ZZ minus plug pin gage with a 0.668-inch nominal diameter, manufactured from steel for use in dimensional inspection and quality control applications. This go/no-go style gage checks whether a hole or bore meets the minimum acceptable size by verifying that the plug fits within tolerance. The minus designation means the gage is ground to the low end of the tolerance band, consistent with Class ZZ specifications. The 19-668-3 carries a tolerance of 0.0002 inches, making it suitable for production-level inspection where high-precision measurement is required but Class Z or ZZ accuracy is acceptable.

This plug pin gage is used in machine shops, manufacturing facilities, and quality assurance departments to verify bore and hole dimensions on machined parts, castings, and fabricated components. It is a standard hand tool for machinists, quality control technicians, and toolroom personnel performing incoming inspection, in-process checks, or final part verification. The gage is sized for holes nominally at 0.668 inches and is appropriate for general production inspection work where Class ZZ tolerance is specified.

Key Features

• Class ZZ minus tolerance designation for production-grade dimensional inspection
• 0.668-inch nominal diameter for direct go/no-go hole verification
• 0.0002-inch tolerance for consistent, repeatable measurement
• Steel construction for durability in shop and inspection environments
• Compact, single-piece plug gage format for fast manual use

Compatibility

Designed for use as a standard Class ZZ minus plug pin gage in applications requiring verification of 0.668-inch nominal diameter bores and holes in production and toolroom inspection settings.

Installation Notes

Plug pin gages are hand-held inspection tools and do not require permanent installation. Store the gage in a protective case away from moisture and abrasive surfaces to prevent wear and corrosion on the ground faces. Before use, clean the gage and the part bore with a lint-free cloth to remove chips, oil, and debris that can affect readings. Handle with care to avoid dropping, as impact damage can alter the gage diameter and invalidate calibration.