Datum in a second view
Datum in a second view
(OP)
The question I have is if a datum is identified in one view as the centerline of a "feature of size", how might I identify that centerline in another view? In the second view the centerline is the starting point for a half dimension and the datum feature is not visible.
Yes, I realize that GD&T would use possibly a profile callout or a TP callout instead of the half dimension. My problem is that I do not have the influence to mandate a chamge to GD&T. I would like to start by properly identifying datums. Currently, a datum symbol may be attached to a centerline that has 5 coincidental features and there is no way to know which feature truly is the datum.
I would put the conventional datum symbol in line with the FOS dimension line in the first view but what do you do in the second view?
Thanks in advance
Yes, I realize that GD&T would use possibly a profile callout or a TP callout instead of the half dimension. My problem is that I do not have the influence to mandate a chamge to GD&T. I would like to start by properly identifying datums. Currently, a datum symbol may be attached to a centerline that has 5 coincidental features and there is no way to know which feature truly is the datum.
I would put the conventional datum symbol in line with the FOS dimension line in the first view but what do you do in the second view?
Thanks in advance





RE: Datum in a second view
Are you familiar with Y14.5?
A datum identifier CANNOT BE APPLIED to a centerline. It must be associated with the FOS.
RE: Datum in a second view
I am afraid that I used to be and now I am out of date with the current standard.
In the older revisions the datum "flag" could be attached to a centerline, identifying a centerline that may have been described by tooling points in another view. would this practice still be acceptable?
Thanks,
Vegabond
RE: Datum in a second view
RE: Datum in a second view
RE: Datum in a second view
RE: Datum in a second view
RE: Datum in a second view
If the datum feature is a feature of size, the datum feature symbol is attached to or associated with the size dimension. By attaching or associating the datum feature symbol with a particular size dimension, it defines a specific point, axis or median plane that is derived from that feature as the datum.
Best Regards,
Heckler
Sr. Mechanical Engineer
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