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jassco, My initial reason for posting my response to you was along the lines of Burunduk's question above. I am aware <CF> can be applied to the toleranced surface, so long as it is applied to the geometric tolerance itself and am very familiar with the figure you indicated. Glad we are in...

Burunduk, Only the first case was really rocking, and definitely over conservative as I noted. The second case was in a stable position, with a gap to illustrate the point that the maximum gap calculated by adding the two flatness tolerance zones assumes that the tolerance zones would always be...

3DDave, Yes I would agree that in your example "nX" is not necessary and indeed should be omitted, as its clear we are only indirectly referencing the pattern of pins but instead directly referencing a single theoretical circumscribed (or inscribed) cylinder. The only way I could see its use is...

<CF> should not be applied to a lone basic dimension.

Ewh/3DDave, That same verbiage exists in the 2009 version as well.

Mako112, While I would agree that this is a reasonable way to assure the gap between two nominally flat parts that mate up to one another, as with most things there are some caveats. If both surfaces are convex, there is the potential for rocking and deviation which may allow gaps larger than...

What standard are you using? If you're just asking about specifying basic dimensions, extension lines as 3DDave mentioned are acceptable and you can ignore the rest of my response. If you're asking about also how to specify how to specify/apply a tolerance to these interrupted features, then...

Ambro92, As greenimi has suggested, profile and position are not interchangeable as they control different aspects of a feature. See below for an example of what I mean. The nice dotted circles are if we assume the feature has perfect form, in that case your largest position deviation is as you...

I'm not sure if you're responding to Burunduk or myself but could you expand on this a bit?

NutZach, Whether or not I think it's important, let's say we added "mathematically defined surface" to the current point/line/plane list of allowed datums. What then? I don't really see how that even helps you without totally reworking how DRFs are defined. You still have to locate and orient...

You have an answer to that already. Even though your complex feature is not symmetric, I'd say it still falls under Y14.5-2009 para 4.3(g) "complex." I don't think discussing theoretical datum geometry helps that much - why not discuss what your simulator/TGC looks like and how it constrains...

Heming, Good luck with deriving a reliable axis from that partial cylinder. In ASME it would not be allowed to apply a position tolerance to this feature, as it is not a FOS and is lacking opposed points. Not sure about ISO, but the same issue will arise with deriving a reliable axis no matter...

I'm not sure I see the value in additional complexity of this type, especially for an uncommon use case in most fields. The section on theoretical datum definition is pretty arbitrary in a lot of ways anyway, I've never thought of it as very important as to what exact theoretical datums...

Heming, I'm not sure I can even tell what the second angled feature is supposed to be from this view, theres a diameter dimension and tolerance but no opposing side from which to measure a diameter? I do see some pretty terrible formatting, and a lone Datum Feature Symbol, but no geometric...

So several have commented about the use of the pitch diameter which was going to be my first point, ie: make sure your datum feature selection reflects function, so I won't add too much there. However you seem to be asking about DOF constraint and order of precedence so I'll add some notes...

engAlright, Ask yourself this - whats the chances you think someone will call you up to confirm if two surfaces at 90deg on the drawing (but aren't labeled) are at 90deg? My guess is pretty much nil. Okay, what about if a 90deg countersink is also not labeled? I would say much higher...

Sharudu, All your Datum Feature symbols should be attached to physical features specified as Datum Features. They should never be applied to theoretical planes, lines, or points. Theoretical datums (planes/lines/points) are derived from the physical Datum Features (or more accurately, their...

These are qualitative evaluations, not quantitative ones. It only confirms what my experience has been, that measurements in these border regions - especially points of tangency - are lacking a rigorous definition without supplementary documentation, and typically are unfortunately left up to...

Burunduk, Could you point me to the place in any Y14 standard (or ISO - honestly curious if they have handled it rigorously) where it is clearly defined what happens where two adjacent/tangent tolerance zones meet? I ask because I've found its something the standard lacks in clarity, however...

I figured there could be some unintended consequences - I agree this could be one of them. I hadn't thought of that, that would be an interesting reason to add a self referencing datum feature however it would align the tolerance zone as you mentioned. Of course as you know the MMB solution...