Spi 34-490-3 Threaded Ring Gage M12x1.75 Class 6G No Go

Product Description

The SPI 34-490-3 is a No Go threaded ring gage used to verify the upper tolerance limit of external metric threads. Manufactured from Oil Hardened Non-Shrinking Steel (OHNS), this single-ring gage is designed for M12 x 1.75 metric threads and is classified to Class 6G tolerances. It ships with an NPL Traceability Certification, confirming the gage meets traceable calibration standards. Machinists, quality technicians, and tool-room professionals use No Go gages to confirm that a threaded workpiece does not exceed the maximum material condition — meaning the gage must not fully thread onto the part to constitute a passing result.

This gage is suited for production inspection environments, tool rooms, and quality control stations where metric external threads must be verified to Class 6G specifications. Class 6G is the standard general-purpose fit for metric fastener threads and is widely applied across manufacturing, machining, and assembly operations. The M12 x 1.75 thread size is common in automotive, heavy equipment, and industrial machinery applications, making this gage a frequently used reference instrument in those environments.

Key Features

• No Go ring gage confirms external threads do not exceed Class 6G upper tolerance limit
• M12 x 1.75 metric thread form, single-ring design
• Constructed from Oil Hardened Non-Shrinking Steel (OHNS) for dimensional stability and wear resistance
• NPL Traceability Certification included for calibration documentation requirements
• Single-ring configuration for dedicated No Go inspection use

Compatibility

Designed for inspection of M12 x 1.75 external metric threads to Class 6G tolerance classification. Use in conjunction with a matching Class 6G Go threaded ring gage to complete a full pass/fail thread inspection.

Installation Notes

Threaded ring gages are inspection instruments and do not require mechanical installation. Handle with clean, dry hands or lint-free gloves to prevent corrosion and dimensional contamination. Store in a protective case away from temperature extremes to maintain calibration integrity. Periodic recalibration against traceable standards is recommended per your quality management system requirements.