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Second case, profile callout

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Andera

Mechanical
Joined
Jan 21, 2019
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I got the following explanation seen below, but I would like to ask if you agree with the assessment? I see here are many GD&T experts that can help me with my follow up questions.
Unfortunately, the discussion I had, has been deleted on the original site, as the people there (original creators) I assume were not happy with the additional questions I’ve been asking them.


The second example is a refinement of Rule #1. As such, it would be inappropriate to have a basic dimension on the size.
If you are not familiar with the hierarchy of GD&T, Profile of a Surface, with a datum reference, can locate &/or orient a feature wrt the datums. Without a datum reference, if the feature is an enclosed boundary, then it will control size and orientation of the feature. If the size is already controlled, and a profile of a surface control is applied without a datum reference, it controls the form of the feature.
In the second example, what is being controlled is co-cylindricity of the 8 surfaces. The only geometric control that locates surfaces is .... profile of a surface.
If you're not familiar with the hierarchy, it's a good time to look at GD&T from that perspective.
I would like to see update the graphic to include a composite profile control as another option



TE_-_Copy_txepnf.jpg
 
For the geometry in figure 11-32 there was no reason not to use parallelism on "EACH ELEMENT" basis instead of profile of a line, but had the controlled feature been interrupted, it could be a legitimate alternative to using the CF symbol (had the number of places been indicated).

Now if an interrupted feature coplanar to the datum feature needed to be toleranced per a similar design intent, there could be a profile of a surface with the number of places indication with reference to the datum feature for the control of the coplanar location of the controlled pattern relative to the datum, and parallelism on EACH ELEMENT basis to refine the coplanarity within the pattern and the orientation relative to the datum.
Or, composite profile.
 
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