About Glastonbury Southern Gage
Precision Measurement Gages & Quality Assurance ToolsGSG
Glastonbury Southern Gage (GSG), established in 1995, is a leading precision measurement tool manufacturer recognized across metrology and quality-control industries. The company was founded by experienced professionals trained at Pratt & Whitney Machine, bringing decades of dimensional inspection expertise into state-of-the-art gage design and manufacturing.
GSG maintains one of the broadest gage catalogs in the industry, producing micrometer masters in sizes from 1.00" to 6.00" (25–150mm) with accuracies to ±0.0001" or ±0.0025mm, all stabilized and ground to match ASME B4.1 tolerance classes. Snap gages follow AGD (Amer. Gage Design) standards for quick pass/fail attribute checking of outside diameters and groove dimensions.
Thread ring gages conform to ASME/ANSI B1.2 and B1.16M international standards, delivering repeatable go/no-go checking for threaded components. GSG also manufactures plug gages, calibration kits, and specialized QC artifacts including QuikChek CMM (Coordinate Measuring Machine) verification blocks designed for interim machine qualification per ASME B89.4.1.
The company operates a modern CNC grinding facility with precision temperature and humidity control, critical for maintaining calibration stability and producing gages that hold dimensional accuracy through years of production-floor use. All tools are individually inspected and certified with traceability to NIST standards.
ChatMRO connects manufacturers and quality teams instantly with the right GSG measurement tool—specify your part dimension, tolerance requirement, and application (production checking, calibration, or machine verification), and our AI surfaces exact gage matches with current calibration status and lead times from our indexed component database.
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Frequently asked questions
What's the difference between a micrometer master and a snap gage?
A micrometer master is a precision cylindrical reference for calibrating micrometers and verifying part dimensions with high accuracy; it reads actual size. A snap gage is a go/no-go tool with fixed upper and lower limits—fast for production but gives only pass/fail feedback, not exact dimension. Use masters for verification; use snap gages for high-volume production checking.
How often should precision gages be calibrated?
Most shops calibrate precision gages annually or per customer contracts, though high-volume production floors may calibrate every 6 months. Environmental factors (temperature, humidity) and frequency of use drive recalibration intervals. GSG provides traceability certificates and can arrange recalibration services to maintain NIST compliance.
Can I use a thread ring gage to check both metric and inch threads?
No—thread gages are pitch and diameter specific. A metric M12 × 1.75 gage will not fit an inch-threaded hole. Always verify thread designation (pitch, major diameter, and series) before ordering. GSG catalogs organize gages by international standard (ASME, ISO, BS) to prevent mix-ups.
What accuracy class (GO/NO-GO tolerance) should I specify for production parts?
Tolerance class depends on your design requirement—tighter tolerances (0.0001" or better) are needed for close-fitting assemblies; looser tolerances (0.001" or wider) work for general commercial parts. Consult your part drawing tolerance; GSG will recommend the appropriate gage class and can custom-grind non-standard sizes.
Why is temperature control critical for precision gage rooms?
Steel and cast iron gages expand and contract with temperature changes—even 1°F can shift dimensions 0.00001" or more at precision levels. Quality assurance rooms maintain 68°F ±1°F to ensure gage measurements remain within calibration. Portable gages used on production floors experience more drift; frequent checks against masters catch drift early.