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Is this profile of a surface FCF redundant

Is this profile of a surface FCF redundant

Is this profile of a surface FCF redundant

I’m trying to interpret only one issue in this drawing, which is the profile of a surface tolerance boxed in red.

Where my question begins is the difference in removing datum D from the FCF and tossing in a lower tolerance. Datum A limits the identified datum feature(vertical surface profile) in 3 DOF. Then Datum E removes 2 DOF. Datum D is only then a linear distance DOF limiter.

I feel the .006 AE feature control frame callout is redundant here. I’m I reading this wrong?


RE: Is this profile of a surface FCF redundant

The lower tolerance is definitely not redundant, since it is refining the profile tolerance to a smaller number. Redundant would be if it's the same number.
It boils down to this: The upper tolerance of .020 controls the location aspect of that surface, and the lower tolerance of .006 controls the form, size, and orientation of the same surface.

Thus, there is a tolerance within a tolerance. But there's no conflict; Recall that profile of a surface controls several qualities at the same time. The .006 is refining certain aspects of the .020, which still leaves the .020 the task of controlling location. (It's somewhat like composite position, if you're familiar with that.)

RE: Is this profile of a surface FCF redundant

The lower segment provides refined control of the shape without defining the location, but with maintaining orientation to A and E.

RE: Is this profile of a surface FCF redundant

Just to add a bit: in the lower segment, the datums are allowed to arrest/stop only rotation DOF's and also the lower datum reference frame shall be a subset of the upper one, therefore the OP's "proposed" and suggested option A|E| on the upper segment and A|E|D| on the lower segment would violate the rules of composite profile and definition of such callout.

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