Basic question regarding constraints

[[Ja...]]

I think that I understand the constraint options when evaluating a feature; constrain the position to get a more repeatable diameter measurement, constrain diameter to get more repeatable position measurements. Is this accurate?

More importantly, I am interested in learning about constraints as applied to datums. For example, when setting up a Position FCF, I have seen some results that don't appear to make sense. If the feature in question can vary in, say X, relative to primary and secondary datums, the Position result appears to account for deviation to each datum in X. This is incorrect and I believe that constraints are the way around this. If I only wanted deviation in X relative to primary, would I go into secondary datum and add primary constraint, or the other way around, or neither?

If anybody has information or resources I would greatly appreciate it.

[[Cl...]]

As for the first question, yes. Some would argue that there
is more to it than that, and there may be some exceptions.

[[Aa...]]

[Deep sigh]
Unconstrained degrees of freedom is a topic that Zeiss doesn't communicate enough information on.

Whenever you set up a "Datum Reference Frame" in Calypso, what it's actually doing behind the scenes is essentially setting up an alignment based on the selected datums. Depending on whether you have ISO 5459 switched on in the settings, each datum may or may not be constrained (in orientation) to the preceding datums. However, if the datums in your DRF do not constrain the position in (to continue your hypothetical) X, Calypso does NOT simply leave that unconstrained and determine it by optimizing the FCF results. Like standard alignments in Calypso, the alignments used for DRFs will inherit any unconstrained degrees of freedom from their parent alignment. (The alignment of the feature controlled by the FCF in question, which, typically will be the Base Alignment.)

If, however, the primary datum constrained the position in X, then the secondary datum would have zero effect, which is what it sounds like your situation is. I would try creating a couple alignments to represent different pieces of your DRF, and see if the position results to those alignments behave as you expect, and how they compare to your DRF results.

(The nice thing about using alignments is that you can spell out which feature constrains which DoF. Sometimes, Calypso is a little wierd about how these are assigned in DRFs.)

[[Ja...]]

Aaron,

That makes things a bit more clear. I was able to get around the issue that I seemed to be having by trying different alignments and really specifying to Calypso which datum constrains which DoF.

Thank you

[[Da...]]

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Guys, sorry to jump in with my very low knowledge. I'm struggling to understand more on this too. Do you have any calypso plans/screenshots that illustrates this to share?