FCF on Reference Dimensions? 1

[serspec]

I recall coming across this before saying that there should not be a FCF on a dimension that is reference. I was trying to find where I saw it before and seem to not be able to find it. What is the rule with this?

I attached a sketch of what I'm talking about.

Thanks for the help.

 

[drawoh]

serspec,

Reference dimensions are provided on drawings to provide information to people who are not responsible for fabrication and inspection of the feature. There are a bunch of assumptions and issues here.
[ul]
[li]The features are controlled by dimensions and tolerances, elsewhere.[/li]
[li]Presumably, someone needs this information. Perhaps the real fabrication dimensions are stacked, and we are helpfully showing the fabricator the total length -- a safe procedure with CAD, particularly[ ]3D, like SolidWorks. I usually show outline sizes and mounting hole dimensions on assembly drawings, if I have an orthogonal view.[/li]
[li]On an assembly drawing or an installation drawing, the user may need to know tolerances. In this case, the FCFs are appropriate. It would not hurt to put in some sort of reference to your dimensioning and tolerancing standard.[/li]
[li]The hazard of providing reference tolerances is the same as the hazard of providing reference dimensions. Someone might change the the real entity on the fabrication drawing, and not bother to track through the total documentation to find all the reference information.[/li]
[/ul]

JHG