Position for noncircular FOS at MMC

[Belanger]

What is the difference between these two subparagraphs?
If you have the 2018 std... compare 10.4.5.1 (a) and (c)
or
If you have the 2009 std... compare 7.4.5.1 (a) and (c)

There are obvious differences in wording, and one refers to a pic for a planar notch while the other refers to elongated slots (with the BOUNDARY explanation).
I get that, but can anyone see a difference in the real substance of the two subparagraphs?

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[greenimi]

Are you asking what would be the differences between these?

"no element of the internal feature of size surfaces shall be inside a theoretical boundary located at true position."

VERSUS


"no element of its surface shall violate a theoretical boundary of identical shape located at true position.

 

[Belanger]

Thanks for chiming in, but not really. I don't see why understanding one of those sentences would require the other sentence (as if they are different in meaning or application).
If you think there's something in the substance/meaning of your underlined words that differs between the two, please expand on it.


John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[3DDave]

I think it is asking a lot for the details like this to have explanations.

 

[Belanger]

3DDave, then you agree that paragraph (a) and (c) are redundant?

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[3DDave]

It looked to me like someone wanted to add another example and they borrowed from one case to elaborate on the other but didn't add anything but confusion.

So, yeah, it looks redundant; whether that was the intention or not.

Recall the standard used to differentiate between "geometric dimensioning" and "rectangular dimensioning" or some such? Because someone wanted to make a point; that was a point that could not be supported so it's gone now. At least this is merely redundant rather than pointless.

 

[axym]

J-P,

I don' think that there is any difference in the substance and meaning of a) and c). It's the same boundary concept, applied to different nominal feature types.

Evan Janeshewski

Axymetrix Quality Engineering Inc.

http://www.axymetrix.ca

 

[pmarc]

It is just my guess, of course, but the reason for having subparagraphs (c) could be that the committee's intent was not to allow usage of BOUNDARY for features other than irregular features of size.

 

[Belanger]

Thanks all. My initial conclusion was that it's a waste of ink.
I still think the same.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems