Spi 19-646-9 Class Zz Minus Plug Pin Gage 0.646 in

Product Description

The SPI 19-646-9 is a Class ZZ minus plug pin gage machined from steel, used to verify bore and hole diameters in precision inspection and quality control applications. It is manufactured to a minus tolerance of 0.0002 inches, meaning the actual diameter is held below the nominal 0.646-inch dimension within that tolerance band. Class ZZ gages are the most common grade used for general-purpose inspection of production parts. Machinists, toolmakers, and quality technicians reach for pin gages when checking drilled, reamed, or bored holes to a known go or no-go standard.

This gage is suited for use in machine shops, fabrication facilities, and inspection rooms where hole diameter verification is part of standard in-process or final inspection. It fits into standard pin gage sets and handles, making it easy to incorporate into an existing gage collection. The 0.646-inch nominal diameter covers a size commonly encountered in mechanical assembly and fixture work. It is appropriate for both bench inspection and floor-level production checks.

Key Features

• Class ZZ tolerance grade for general-purpose production inspection
• Minus tolerance of 0.0002 inches holds the gage below nominal for go-gage applications
• 0.646-inch nominal diameter in hardened steel construction
• Lightweight at 0.2 pounds, suitable for handheld use
• Compatible with standard pin gage handles and sets

Compatibility

Designed as an OEM-style replacement or direct addition to standard Class ZZ pin gage sets and handles accepting 0.646-inch diameter gage pins.

Installation Notes

Pin gages should be handled with clean, dry hands or inspection gloves to prevent corrosion from skin oils. Before use, verify the gage and workpiece bore are at a stable temperature, ideally 68 degrees F, to avoid thermal expansion errors. Insert the gage gently into the hole being checked without forcing or rotating under pressure, which can cause premature wear. Store the gage in a protective case away from other tools to preserve the ground surface finish.