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GD&T Flatness

GD&T Flatness is a common symbol that control how flat is a surface of a feature regardless of any other datums. Usually, a value will be indicated in the control box to identify the require flatness.

Flatness can be easily measured using a height gauge or a dial gauge run across the surface of the part. High Gauge can be seat on the surface to be measure if the surface is large enough.

Flatness in GT&T



Flatness vs parallelism Flatness and parallelism is never the same.
Flatness measures the condition of a surface in one plane and it is a feature compare to it self within the same plane. While Parallelism compare the condition of a surface or axis from another datum plan or axis.


Click on the following links to get more information on GD&T concept.


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