Spi 29-158-3 Class Zz Plus Plug Gage 0.158 Inch

Product Description

The SPI 29-158-3 is a Class ZZ Plus plug gage designed for precision hole inspection in machining and manufacturing environments. It measures a nominal bore diameter of 0.158 inches with a tolerance of 0.0002 inches, making it suitable for go/no-go verification on close-tolerance drilled, reamed, or bored holes. Constructed from steel, this gage is built to withstand repeated use in shop-floor conditions. Metrology technicians, machinists, and quality control personnel use plug gages like this one to confirm that a hole falls within its specified dimensional limits before assembly or finishing operations.

This gage is applied wherever small-diameter bore verification is required in production or inspection settings. Typical use cases include checking pilot holes, clearance holes, and precision-reamed bores in components made from metal, plastic, or composite materials. The 0.158-inch diameter range addresses common fractional and decimal-equivalent hole sizes found in light mechanical assemblies and instrument components. It is equally at home on a job-shop floor or in a quality lab performing incoming or in-process inspection.

Key Features

• Class ZZ Plus tolerance classification for plug gage applications in production inspection
• 0.158 inch nominal measurement diameter for small-bore verification
• 0.0002 inch tolerance for close-tolerance dimensional confirmation
• Steel construction for durability and dimensional stability under repeated use
• Compact, lightweight design at 0.2 pounds for easy handling and storage

Compatibility

Designed as an OEM-style replacement or equivalent plug gage for use in any go/no-go inspection setup requiring a 0.158-inch diameter Class ZZ Plus gage.

Installation Notes

Plug gages are handled and used by machinists or quality technicians — no power tools or utilities need to be shut down before use. Store the gage in a protected case away from abrasive surfaces to preserve the lapped finish and dimensional accuracy. Clean the gage and the bore being measured before inspection to prevent false readings from chips or coolant residue. Calibration interval and handling procedures should follow ASME B89.1.5 or the applicable shop quality plan.