Can you use FOS with Straightness as Datum

[zRock]

Is the Datum A callout legit, in attachment?
--using FOS with straightness as Datum (in attached drawing)

https://files.engineering.com/getfi...-98fe-4a96-a242-4b2c908accd3&file=Callout.JPG

Thanks,

 

[greenimi]

Well, the picture is from Alex Krulikowski so some trust should be in the book itself.
Looks correct in my book.

 

[Burunduk]

Looks OK.
Why do you doubt it?

 

[chez311]

Sure, why wouldn't it be? You could put it in line with the diameter dimension, or on the circumference in another view, but hanging it off the FCF is perfectly valid.

Assuming you're going by ASME (a fair assumption based on the symbology and terminology in the attached figure) if you want textual evidence its mentioned several places in Y14.5 as well in a multitude of figures. The verbiage does not limit this practice to a particular type of control.

Where a feature or pattern of features controlled by a
geometric tolerance also serves as a datum feature, the feature control frame and datum feature symbol may be combined. The datum feature symbol may be attached to the feature control frame. See Fig. 3-27.