Hi Chez,
You are absolutely correct.
The unfortunate reality, in my experience, is that it isn’t until after a mistake has been made that the nominal dimensions of the model are scrutinized.
Jake
Hi sendithard,
*Full disclosure, I did not watch the video that you linked. Here goes:
It is the designer's job to determine what the size of any feature should be to ensure proper functionality of the part. The tolerancing of said features should similarly reflect the functional requirements...
Hi destes,
Assuming you are working to the 2009 standard:
4.24.4 (p. 85) "Where it is determined that an area is necessary to assure establishment of the simulated datum (that is, where spherical or pointed pins would be inadequate), a target area of the desired shape is specified."
I would...
My preferred method is to use symmetric tolerancing (20.5 +/- 0.5, in this case). All the methods that CheckerHater mentioned effect the same result when toleranced appropriately, but drawing dimensions are commonly generated from 3D CAD data that is also used to program toolpaths with CAM...
