Need help interpreting this drawing feature control frame A, Is it right to refer the datum B in feature control frame to which it is attached? 1

[shiva@im_engineer]

 

[jassco]

Datum feature "B" is self-referenced.

 

[3DDave]

The feature control frame for datum feature B should only have a perpendicularity geometric characteristic symbol and only reference datum feature A.

Is this from a text book or a test?

 

[shiva@im_engineer]

The feature control frame for datum feature B should only have a perpendicularity geometric characteristic symbol and only reference datum feature A.

Is this from a text book or a test?

Text book

 

[3DDave]

What was the discussion about this figure in the text book?

 

[shiva@im_engineer]

It was an execise, to find out permisible datum shift at each reference frame
Then i observed this if a datum is referenced at the same place where it is defined how can i calculate datum shift and it didnt make sense to me

 

[shiva@im_engineer]

Of course Solution in the book is zero, but found no explanation

 

[greenimi]

Of course Solution in the book is zero, but found no explanation

Would you mind to provide the name/edition of the book and the author?

 

[shiva@im_engineer]

Fundamentals of GD&T by Alex Krulikowsky

 

[greenimi]

Fundamentals of GD&T by Alex Krulikowsky

Which page?
Also which edition?

 

[SeasonLee]

Fundamentals of GD&T by Alex Krulikowsky

There are some imperfect areas at the 3rd edition(based on 2009 std), please look at the textbook published by SAE based on 2018 standard, Alex made an update on that figure as shown below.



Season

 

[greenimi]

There are some imperfect areas at the 3rd edition(based on 2009 std), please look at the textbook published by SAE based on 2018 standard, Alex made an update on that figure as shown below.

Thank you Season for clarification. I appreciate you looking into it.
(I found the culprit on page 211, AK, 3rd edition)

 

[Burunduk]

The 2018-based version is better and clearer.
With that said, having hole B positioned relative to itself as a secondary reference at MMB, although quite weird, is not "illegal", and it would not yield a zero actual value so it still does something. It's an odd way to control orientation, but it doesn't control location.