Tertiary axis/plane is parallel to primary axis

This DRF is invalid. PCD will never let you use -C- in XACT Measure because all 6 degrees of freedom are already constrained by your primary & secondary.

DBC interpreted literally would mean Level Z+ (or Z- depending on vector to Cyl_D, rotate Plane_B to Y+ about the direction of -D-, make -D- X AND Y origin, and make a plane or point on top face to set your Z origin. -C- would get entirely ignored as tertiary.

Thanks a lot, I haven't heard the CAN-MAY-MUST thing until I was looking up stuff for this problem. You are saying that adding Dat-C- is redundant because it doesn't add any new constraints.

And PC-dmis just doesn't like that I guess?

According to ASME Y14.5, since the datum flag is attached to the true position, the pattern is datum D. In this case, datums B and C would not be able to constrain anything that is not constrained by datum D. Only 5 axes are constrained (all by datum D), since nothing is restricting the up and down movement (A is the only datum that can constrain this movement).

Alright. I just have to triple check some things because I'm 22 and don't really want to tell engineer it is drawn up wrong when they have been running these for years apparently.

Don’t the counter sinks in Datum D control the up and down?

The part needs to conform to EU standards and maybe the part needs to be ISO compliant, not ASME.

Just a thought.

Datum D can't be primary because then it will conflict with datum B. I think should be A/B/C or so.

He asked about DBC so I gave a correct explanation of what that DRF means. My advise was not specific to a certain spec, or telling him how I THINK he should do it..just explaining basic "can-may-must".

If he measures the part the way I said, he'll get BLUEPRINT CORRECT dimensions off of the part. That may be different then the Engineer's "design intent" for the part but that's their mistake, not his. I run into this issue a lot. When this happens, open and respectful dialogue with the designer is key. If you're 22, don't be foolish enough to tell anyone they're wrong for at least the next 10 years def go about that one a different way my friend!

In THIS scenario, I would defer to the Engineers & do what they say. You need to get along with them. They have history on the part and it sounds like they know how they want it done.

Going forward, get some GD&T training. After that happens you'll be able to speak from an educated standpoint when things don't make sense. I work with BRILLIANT engineers who quite commonly mess up their GD&T. They're doing their best but they're human too. If the CMM programmers at our company weren't as well versed in GD&T as we are, there would be a lot of bad parts up there right now lol.

@Darius11
With all due respect, you're incorrect. -D- can be, and is, the primary datum. The engineer put it first in the DRF, that makes it so. Regardless of how much it may not make sense to us, it is mathematically acceptable. It also would not conflict with -B- (as they have perpendicular surface vectors).