fig 4-16 -Y14.5-2009 and datum feature C -as tertiary
fig 4-16 -Y14.5-2009 and datum feature C -as tertiary
(OP)
If we remove datum feature C from the positional callout of Ø7.0 OD, does the meaning of the drawing or 4.11.6.1 (a, b and c)subsequent explanations change?
If yes, how?
If no, why?
If yes, how?
If no, why?





RE: fig 4-16 -Y14.5-2009 and datum feature C -as tertiary
Not an expert. I would say : No (does not change the meaning for 4.11.6.1 )
I can provide a picture for quick reference.
If I am wrong, I will stand corrected.
RE: fig 4-16 -Y14.5-2009 and datum feature C -as tertiary
Certified Sr. GD&T Professional
RE: fig 4-16 -Y14.5-2009 and datum feature C -as tertiary
RE: fig 4-16 -Y14.5-2009 and datum feature C -as tertiary
Certified Sr. GD&T Professional
RE: fig 4-16 -Y14.5-2009 and datum feature C -as tertiary
Therefore, C does nothing?
Can we conclude just that?
Or that is a stretch/ unfortunate misleading?
RE: fig 4-16 -Y14.5-2009 and datum feature C -as tertiary
I agree with your statement for the simultaneous reqmnt. But I always waffle at not adding the "extra" datum (C). Although redundant, datum C adds clarity for those who are not cognizant with simultaneous reqmnt conventions.
Certified Sr. GD&T Professional
RE: fig 4-16 -Y14.5-2009 and datum feature C -as tertiary
In reality you would only not have a datum C if there were no keyway, just a simple hole for Datum B, correct? But then the Datum D would become your clocking feature, that is needed, to use a profile geometric tolerance to describe the outer periphery of the part. Still correct?
RE: fig 4-16 -Y14.5-2009 and datum feature C -as tertiary
No.
Zero basic implied.
Sim Req. in effect.
RE: fig 4-16 -Y14.5-2009 and datum feature C -as tertiary
RE: fig 4-16 -Y14.5-2009 and datum feature C -as tertiary
The language in the standard is vague on this. Perhaps:
When a Datum Reference Frame is referred to in multiple feature control frames, including datum feature modifiers, then the part shall not be repositioned when checking individual features that have tolerances based on that Datum Reference Frame.
RE: fig 4-16 -Y14.5-2009 and datum feature C -as tertiary
Well nobody said it does apply to sub-sets. If you are reading a little more careful the thread the OP talked about removing C and then DRF to become A and B, same as the slot
RE: fig 4-16 -Y14.5-2009 and datum feature C -as tertiary
I should have fallen back to an investigative method I suggested before, which is to envision the gauge required for each case and see if there would be any difference between them. This avoids trying to figure out which part variations are compliant in favor of looking at the compliance criteria. Since the simulator for C{M} is identical to the one that verifies the slot location, there is no difference, so I agree.
If [-D-] is changed to be controlled by [A|B(M)|C], in which case the gauges would not be the same for the removal of C.