Ring Gages to Check Size Dimensions

In this Question Line video, Jason answers the following video about ring gages: 

I am speaking of the size of the outside diameter 2.002-2.005 with circularity of .007 inches. If we verify the OD with a go/no-go ring gage will this not essentially take tolerance away from the part since we all know a 2.005 Ring gage will not fit over a 2.005 inch diameter? How does circularity come into play? If the part has a spot reading slightly oversized going around the diameter, but the “average” comes in utilizing the .007 circularity, are parts not to print spec?

 

Jason discusses the drawing below, explaining that Rule #1 controls the size and form of a feature of size, and what this means for ring gage design and inspection reporting. He also explains why the circularity callout in this drawing is incorrect. 

 

 

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For more information on ring gages and how go/no-go gages are used to verify that a feature of size meets Rule #1 of GD&T, check out this article: Go/No-Go Gaging and Rule #1. 

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