Feature of size for 2 plane features

[Frokilin]

Hi,

I believe this image here attached is not a FOS. If I am not right, please let me know.
I just can't get a clear reason on the ASME 2018 standard since I find the definitions a little confusing to me. I have read online about the "2 opposed points" but I can't find something similar on the standard.

 

[greenimi]

Look for regular FOS

regular feature of size: one cylindrical surface, a spherical
surface, a circular element, or a set of two opposed parallel
line elements or opposed parallel surfaces associated with
a single directly toleranced dimension

 

[Frokilin]

Thanks greenimi. I guess I was missing the AME definition for the Irregular FOS to completely understand all the cases.

Looking at 3.29 for the definition of actual mating envelope and then 3.35 for the different definitions of FOS, that example above doesn't fall under any of them

 

[jassco]

It is related to Computational Mathematics. Feature of sizes are more stable.

 

[greenimi]

Looking at 3.29 for the definition of actual mating envelope and then 3.35 for the different definitions of FOS, that example above doesn't fall under any of them

Because in your example above the feature is not a FOS (neither regular or irregular). It is a surface, not a FOS.
So you have to control the relationship between two surfaces.

 

[Frokilin]

Because in your example above the feature is not a FOS (neither regular or irregular). It is a surface, not a FOS.

Yes, maybe I didn't explain myself well, but that's what I meant, that after carefully reading those paragraphs together wit the defection of AME, it's indicating that the example is not a FOS

 

[jassco]

Take a look at this image. Is this feature of size? Of course, not.