6 Replies Latest reply on Jun 4, 2018 2:08 PM by Steve Calvert

    How to establish datum plane for a width feature of size.

    Tran Van Quang

      Hello everyone,

      I read about establishing datum for a width feature of size in "ASME Y14.5-2009" and "GD&T mechanical design".

      But there are seem two different way to establish datum, for example in this picture below:


      According to "GD&T mechanical design", datum B is the 7 inch size feature between the left and right edges.

      But according to "ASME Y14.5-2009", it will be the  center plane between left and right edges.


      So what is the right datum here? And how to make a mating gage for such center plane