QUESTION
One example uses parallelism and perpendicularity while the other uses profile. I’m sure they are inspected differently but are they geometrically the same thing?
REPLIES
mkcski
At first glance: you cannot use BSC dimensions with parallelism and perpendicularity to control the size of the block. So your comparison question is somewhat moot.
The relationship between Datum A and the top face is not parallelism but is perpendicularity. So the control is not per Standard. From a drafting standpoint, the controls only apply in the view shown. So you should apply the control in the end view. You have taken a reasonable liberty in showing the “perpendicularity” relationship by identifying Datum in the front view. But I assume the block is “square” so other views maybe needed to confirm my assumption.
In the profile example, Datum B is included in the profile tolerance. Although technically possible, it is not good practice to have a feature related to itself.
SOURCE
https://www.eng-tips.com/viewthread.cfm?qid=427146
Above is a snippet.