Spi 19-420-9 Class Zz Minus Plug Pin Gage 0.42 Inch

Product Description

The SPI 19-420-9 is a Class ZZ minus plug pin gage used to verify hole diameters in precision machining and inspection applications. It measures 0.42 inches in diameter and is manufactured from steel for durability and dimensional stability. Class ZZ is the standard tolerance grade for general-purpose go/no-go gauging, and the minus designation means the gage is ground to the low side of the nominal diameter. The 19-420-9 carries a tolerance of 0.0002 inches (0.0002 mm), making it suitable for moderate-precision inspection work. Machinists, quality control technicians, and tool room personnel are the primary users of this type of gage.

Plug pin gages of this type are used in manufacturing facilities, machine shops, and inspection departments to check drilled, reamed, or bored holes for conformance to print tolerances. The 19-420-9 is appropriate for use in both production floor and bench inspection environments where Class ZZ accuracy is specified. It is a single-ended pin gage intended for hand-held use without a dedicated handle, though it is compatible with standard pin gage handles sold separately.

Key Features

• Class ZZ tolerance grade for general-purpose hole inspection
• Minus designation — ground to the low side of nominal diameter
• 0.42 inch nominal diameter
• Steel construction for hardness and dimensional stability
• Tolerance of 0.0002 inches for moderate-precision gauging

Compatibility

Designed as a standard Class ZZ minus plug pin gage for use in general-purpose go/no-go inspection of 0.42 inch nominal diameter holes. Compatible with standard pin gage handles designed for this diameter range.

Installation Notes

Pin gages should be handled with clean, dry hands or lint-free gloves to prevent corrosion from skin oils. Before use, verify the gage and workpiece are at the same ambient temperature to eliminate thermal expansion error. Do not force the gage into an undersized hole, as this can damage the gage surface and affect accuracy. Periodic cleaning and light oiling per the manufacturer or shop calibration program will maintain gage integrity.