Spi 19-438-1 Class Zz Minus Plug Pin Gage 0.438 in

Product Description

The SPI 19-438-1 is a Class ZZ minus plug pin gage designed for go/no-go inspection of drilled, reamed, or bored holes in production and quality-control environments. Built from steel, this gage checks whether a hole falls within the specified tolerance band. The nominal diameter is 0.438 inches, and the Class ZZ tolerance is 0.0002 inches minus, meaning the gage is ground slightly under nominal to allow for wear allowance on the minus side. Machinists, toolmakers, and quality technicians use plug pin gages like this one to verify hole size quickly and consistently without requiring a measuring instrument readout.

This gage is suited for light-duty inspection work in job shops, tool rooms, and manufacturing facilities where Class ZZ accuracy is acceptable. Class ZZ is the most commonly stocked commercial-grade pin gage class, appropriate for checking general-tolerance holes rather than precision or lapping-grade fits. It fits into standard gage handle sets and is typically used as a go member or as a standalone check pin for 0.438-inch nominal holes.

Key Features

• Class ZZ minus tolerance for general-purpose hole inspection
• Nominal diameter of 0.438 inches with a 0.0002-inch tolerance
• Steel construction for durability in production use
• Compatible with standard pin gage handles for easy handling
• Single-piece packaging suitable for individual replacement or kit supplementation

Compatibility

Designed as a standard Class ZZ minus plug pin gage for use with conventional pin gage handle sets accepting 0.438-inch diameter pins.

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 the workpiece bore are at the same ambient temperature to avoid thermal expansion error. Do not force the pin into a hole; apply light, consistent hand pressure only. Store the gage in a protective case or with a light coat of rust-preventive oil when not in use.