Profile Callout Bilateral 2

[Ksplice]

Hi,

I have a question on profile tolerances called out bilaterally. please see attached sketch. the profile callout is pointing to a line that is 0.10 inside the actual profile. my interpretation of this is that the tolerance zone is established centered on the 0.10 offset. is this correct or does the zone start at the 0.10 and is not centered on it. Also if someone could point me to the page in the ASME 2009 standard where this is addressed i would most appreciate it as i have been unable to find it.

thanks,

 

[pmarc]

I just received answer from Alex:

"I agree with your original statement that composite profile may be applied to a single feature. The standard does not make this very clear, but there are words that support your position. I will propose an example of composite profile tolerance applied to a single feature in the next version of the standard. I can’t guarantee it will be added, but I will try. I will also update my fundamentals of GD&T book when I make another printing."

 

[SeasonLee]

Thanks, pmarc

Just confirm with you the words " A composite profile tolerance can only be applied to patterns of surfaces" will be revised by adding "may be applied to a single feature", am I right?

Season

 

[pmarc]

SeasonLee,
I have no idea how the revised text will look like. I am however pretty sure that "A composite profile tolerance can only be applied to patterns of surfaces" will not be there any more.

 

[fsincox]

I like Mark Foster's positions in general, for a while I thought pmarc might be him because of the depth of knowledge and dedication pmarc has shown me here also the fact he had "marc" in his name. I mean no offence.
Mr. Foster does seem a little more open to expanding the standard concepts than some here and I feel, as most know, it is basically required in order to deal with real life situations (make the standard relevant). I read the yahoo group specically for his posts.
Frank

 

[SeasonLee]

According to Alex’s latest textbook Fundamentals of GD&T:

A common misconception about profile of line is that it should be applied to thin parts (e.g., a gasket), he gives us one example of profile of a line applied on a surface of a thick part, based on this example and view point, I can image and understand the legality of composite profile of line control on the OP's case. There are several real-world applications for a profile of a line tolerance on a drawing. Traditionally, profile of a line has been applied to aerodynamic, hydrodynamic, and ergonomic surfaces to facilitate inspection of the surface at specified cross section. Applications may include contours of:
• Automobile seats
• Propeller blades
• Electric razor body

And, this is the author’s comment: The use of profile of a line is rare on engineering drawings, there are very few functional applications that require profile of a line.

Season