constrain features when using in characteristic

[[Ja...]]

In any characteristics window, when you select a feature to be used. The option to constrain that feature is available. Can anyone explain to me what exactly does that do and when to use it, especially when using it in TP characteristic?

[[Cl...]]

Constrains degrees of freedom, e.g., size, or position.
One of the more knowledgeable guys in here can
elaborate more on the subject.

[[Ma...]]

Constrain, eval and filter can be adjusted in feature of characteristic.
Characteristic always take settings from feature as basic settings, but you can adjust it. If you edit this in feature, then you can affect more next features.
But in characteristic you affect only in itself ( excluding adjusting in alignments )

[[Ja...]]

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Thank you for that information but how does it affect the characteristic results. What does it actually do when u constrain the feature to be used in characteristic to another feature?

[[Me...]]

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The easiest explanation *in regard to True Position* is that it is simulating the actual or unrelated envelop according to the ASME Standard. Think of it as if you were assembling mating parts. The evaluation method will always be outer tangential and those high or low points would be projected or intersected to the higher or lower points of the upper precedent datum.

I may be incorrect about the envelop wording but I'm sure folks in here can explain it a lot better than me.

[[Ja...]]

An example is if you measure a small arc and ask for radius you might get a bad result, but if you constrain the location, the center point of the radius is not aloud to move from nominal and the radius result improves. You can also constrain radius to get a better position result.

[[SH...]]

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Ok, got it.

[[No...]]

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I think you mixed something up here. Constraining has nothing to do with envelope calculation. That would be the option above Constrain (in the picture) where it reads "LSQ...". But then, I don't know what the ASME standard says....

[[No...]]

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When you constrain a feature, you literally fix the selected coordinates to their nominal values. What that does is, it doesn't allow the selected fitting method (LSQ etc.) to use that coordinate for fitting. It just stays fixed to nominal. To have the Constrain option available doesn't mean that it always makes sense to use it. The most-used case is the radius example mentioned above. I don't know where it might be useful in a TP scenario.

[[Me...]]

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According to the cookbook they coincide when one is to follow the ASME standard method of calculating True Position. When you check the "Outer Tangential" option in the Environment settings, this is what Calypso automates when you select your datums for a True Position. It automatically selects Outer Tangential Evaluation regardless of feature, and it automatically constrains features to those upper precedent datums.