Spi 29-438-9 Class Zz Plus Plug Gage 0.438 in

Product Description

The SPI 29-438-9 is a Class ZZ Plus plug gage designed for go/no-go dimensional inspection of bored holes, drilled passages, and machined openings at a nominal diameter of 0.438 inches. Class ZZ Plus gages are manufactured to a tolerance of 0.0002 inches, making them suitable for production inspection tasks where consistent hole-size verification is required. The steel construction provides durability through repeated use in shop-floor environments. This gage is used by machinists, quality technicians, and tool-and-die professionals to confirm that a feature meets dimensional specification before assembly or further machining proceeds.

This plug gage is applied in manufacturing and machining operations where hole diameter must be verified to a defined tolerance. Typical use cases include incoming inspection, in-process quality checks on CNC or manual machine output, and final inspection before component release. The 0.438-inch nominal size fits a range of common fastener clearance holes and precision-bored features found in mechanical assemblies, hydraulic components, and pneumatic fittings. It is well suited to both job-shop and production-floor inspection stations.

Key Features

• Class ZZ Plus tolerance grade at 0.0002 inches for reliable production inspection
• Nominal measurement diameter of 0.438 inches
• Steel construction for wear resistance and dimensional stability
• Compact and lightweight at 0.2 pounds for easy single-hand use
• Individual unit packaging suitable for tool crib or inspection kit storage

Compatibility

Designed as an OEM-style plug gage for go/no-go inspection of 0.438-inch nominal diameter holes in general machining and quality-control applications.

Installation Notes

Plug gages require no installation but must be handled and stored correctly to maintain accuracy. Always clean the gage and the feature being checked before use to prevent debris from affecting readings. Do not force the gage into an undersized hole, as this can damage the gage surface and alter its calibration. Periodic recalibration against a traceable standard is recommended to confirm the gage remains within its stated tolerance class.