April 15, 2025
Metric Thread Callouts: M20×1.5-6H and Tapped Holes
An order for an 'M20 thread gauge' is missing three of the four things needed to make one. Each element of a metric callout, and what an omission does.
Practical guidance on gauging, calibration, standards, and shop-floor quality, from the DSN engineering team.
An order for an 'M20 thread gauge' is missing three of the four things needed to make one. Each element of a metric callout, and what an omission does.
An order that says '25 mm plug gauge' leaves six decisions to whoever makes it. Here is the full specification, and what each omission tends to cost.
Both gauges passed, so the part shipped. Limit gauging proves less than most operators assume. Here is what GO and NO-GO each verify, and what neither of them sees.