Spi 29-821-6 Class Zz Plus Plug Gage 0.821 in Dia

Product Description

The SPI 29-821-6 is a Class ZZ Plus plug gage designed for go/no-go dimensional inspection of bored holes, machined openings, and precision-drilled features. It measures a nominal diameter of 0.821 inches with a tolerance of 0.0002 inches, placing it within the Class ZZ Plus accuracy grade suitable for production inspection and quality control work. The gage is constructed from steel for wear resistance and dimensional stability across repeated use cycles. Machinists, quality technicians, and tool room professionals use this type of gage to verify hole diameter conformance to print specifications quickly and without complex setup.

This plug gage is suited for use in machine shops, production floors, and inspection departments where hole diameter verification is a routine task. Class ZZ Plus gages are typically applied to medium-tolerance production work where Go and No-Go limits must be confirmed on drilled, reamed, or bored features. The compact size and steel construction make it practical for bench inspection and in-process checks on ferrous and non-ferrous workpieces alike.

Key Features

• Nominal measurement diameter of 0.821 inches for direct hole inspection
• Class ZZ Plus accuracy grade with 0.0002 inch tolerance
• Steel construction for wear resistance and long service life
• Single-piece package quantity suitable for individual inspection stations
• Lightweight at 0.2 pounds for easy bench and in-process handling

Compatibility

Designed as an OEM-style fixed-limit plug gage for use in standard go/no-go inspection applications requiring a 0.821 inch nominal diameter and Class ZZ Plus tolerance grade.

Installation Notes

Plug gages are installed and used by quality technicians and machinists as part of dimensional inspection routines. Before use, clean both the gage and the workpiece bore to remove chips, coolant, and debris that could affect measurement accuracy. Handle the gage by the knurled handle or body to avoid thermal expansion from hand contact with the measuring surface. Store in a protective case away from abrasive materials to preserve the ground and lapped gage surface.