Simultaneous requirement within composite positioning

[[Ja...]]

I get the feeling I haven’t been programming my composite positions correctly. In the following example I would do a true position for each of the 12 holes to satisfy the top tier. I would then do a best fit to satisfy the bottom tier. Each tier gets analyzed, but in separate characteristics. According to the callout, both tiers need to analyzed simultaneously. How do I tie the second tier to the first tier so they’re being analyzed simultaneously? The example is just a simple cover so I’m not too worried about it not fitting the mating part. However in some of our heavy, solid, non-forgiving parts I’m afraid we’ll run into a non-fit situation even though the Calypso printout says both tiers are good when analyzed independently like I’ve been doing.

[[Th...]]

I can't think of a situation where simultaneous requirements would apply to a composite position, at least not if it's the only one on the print. It would require the datum reference frames to be identical, and that would render either the upper or lower frame redundant. There's no fit allowed by that upper frame anyway. I'm pretty sure you're handling the positions correctly.

[[Da...]]

You're right, it's not a simultaneous requirement as in Chapter 7.19 of ASME Y14.5-2018, but I think Jack Nelson means each requirement of the two tiers must be met (of course) for all holes simulatenously (all holes for tier 1 simultaneously and the same for tier 2, but not tier 1 and 2 simultaneously).

That can be done by evaluating the holes as a pattern rather than each hole individually.

In this call-out BTW it doesn't make a difference if you treat the position requirements as a composite call-out or as individual ones, because the second tier doesn't even provide a datum that would locate the hole pattern. If, on the other hand, the datum on the second tier was A|C for example, the composite position would use C as a rotational constraint only, but not as a translational constraint.

[[Ja...]]

Thanks for the clarifications.

[[Th...]]

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Ah, I wasn't paying attention to the attribute bubbles. Our internal method has been to assign one for the upper frame and one for the lower, so I didn't even think about it.