We ended the previous gaging article talking about the 10:1 rule as it applies to the performance of a gage.

The rule says that the gage should perform to a level better than 10% of the tolerance. Although this rule has mostly been replaced by the more scientific and standardized GR&R performance test, other rules of thumb are still in play.

Gage design

For example, we gage builders take this 10:1 rule a little further. To build a gage that performs better than 10% of the tolerance in use, we need to design a gage that performs to 4% of the tolerance with the things we can control—namely, the gage components and the master. That’s pretty demanding, but it has a foundation in logic.

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