Spi 29-040-3 Class Zz Plus Plug Gage 0.04 Inch

Product Description

The SPI 29-040-3 is a Class ZZ Plus plug gage designed for precision inspection of small-diameter holes and bores. Built from steel, this go/no-go style gage measures hole diameters at 0.04 inches with a tolerance of 0.0002 inches, making it suitable for applications where tight dimensional control is required. It is used primarily by machinists, quality control inspectors, and tool-and-die professionals working in manufacturing, aerospace, and general metalworking environments where hole conformance must be verified to print specifications.

This plug gage is suited for inspecting drilled, reamed, or machined holes at the 0.04-inch nominal diameter. Class ZZ Plus gages occupy a step above standard Class ZZ tolerances, providing tighter gage accuracy for production inspection where measurement uncertainty must be minimized. Typical applications include incoming inspection, in-process quality checks, and final part verification on machined components.

Key Features

• Class ZZ Plus tolerance class for tighter inspection accuracy than standard Class ZZ
• 0.04-inch nominal measurement diameter for small-bore inspection
• 0.0002-inch tolerance for precise dimensional verification
• Steel construction for durability and wear resistance in shop environments
• Compact single-piece form factor suited for bench inspection or floor use

Compatibility

Designed as a direct-use plug gage for inspecting machined holes at 0.04-inch nominal diameter in accordance with Class ZZ Plus gage standards.

Installation Notes

Plug gages are handled and used by quality control technicians or machinists — no power source or mechanical installation is required. Keep the gage surface clean and lightly oiled when not in use to prevent corrosion. Do not force the gage into a bore; improper force can damage both the gage and the workpiece. Store in a protective case away from abrasive materials to maintain calibration integrity.