Spi 29-551-9 Class Zz Plus Plug Gage 0.551 in

Product Description

The SPI 29-551-9 is a Class ZZ Plus plug gage designed for go/no-go dimensional inspection of bored holes and machined features at a nominal diameter of 0.551 inches. Built from steel, it holds a tolerance of 0.0002 inches, meeting Class ZZ Plus accuracy standards for inspection-grade measurement work. This gage is used by machinists, toolroom technicians, and quality control personnel to verify that drilled, reamed, or bored holes fall within specified dimensional limits. Its compact, single-piece construction allows for quick manual checks on the shop floor or in the inspection lab.

This plug gage is suited for production and job-shop environments where hole diameter verification is part of a standard inspection routine. It is appropriate for use on steel, aluminum, and other common workpiece materials wherever a 0.551-inch nominal bore diameter must be confirmed. The part ships as a single gage unit and is intended for hand use without special fixtures or mounting hardware.

Key Features

• Class ZZ Plus tolerance grade — 0.0002 inches — for inspection-quality dimensional verification
• Steel construction for wear resistance and dimensional stability during repeated use
• Nominal measurement diameter of 0.551 inches for precise hole gauging
• Single-piece plug design allows fast, tool-free go/no-go checks
• Lightweight at 0.2 pounds — easy to handle during high-volume inspection runs

Compatibility

Designed as an OEM-style inspection tool for verifying 0.551-inch nominal bore diameters in machined components across general metalworking, toolroom, and quality control applications.

Installation Notes

Plug gages are installed by hand — no power tools or torque equipment are required. Before use, clean the gage and the bore being inspected to remove chips, coolant, and debris that could affect readings or damage the gage surface. Store the gage in a protective case when not in use to prevent nicks or corrosion that would compromise tolerance accuracy. Calibration should be verified periodically against traceable standards per applicable metrology procedures.