True Position of a hole

[[Ri...]]

I have a part that I am checking some true positions of holes back to 3 datums. When I the true position option is opened, it gives me some different methods of inspection, ie. Diametral, rectangle,polar, x only, y only and the like. depending on which i choose, I can get wildly different answers to the "true position" Also, there are 2 of the holes of the same diameter on either face and one checks within tolerance, the other out by like .030" which there is no way it's out of position that far, which leads me to believe I have something programmed incorrectly on the CMM.

[[Ma...]]

Type of tolerance is set by callout on drawings. Diameter sign for diametral / without sign for rectangle / with text or sign for different tolerance for each of axis.

If it can be off is question how datums. Perhaps better would be to make standard alignment than filling datums in callout ( someone can make mistake in filling ).

Also ASME / ISO can make difference

[[To...]]

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Please explain. The only difference that I am aware is how the feature of interest is evaluated. I've attached how the cookbook recommends to evaluate a bore in a position call-out. I don't think most ASME Calypso users bother to follow the "Recall One Feature" methodology. I know I don't. Not sure why. Maybe too much extra work? Maybe when Calypso adds checkboxes for ISO and ASME, it will do this automatically.

I'm guessing most ASME users don't bother to change the evaluation of the feature to Outer Tangential either. This should be a functional fit. If you use the Recall One Feature" methodology, the OTE evaluation must be applied on the original cylinder because the created theoretical cylinder doesn't give you the option to change the evaluation. Seems to me that using the original feature and changing the evaluation of the feature to OTE within the position would solve the problem. Is it that easy?

Also, if you use the "Recall One Feature" methodology, the nominal values of the created theoretical cylinder are created from the actuals using formulas which requires the nominal values to be edited in the position.

I don't understand how the LSQ evaluation provides for a functional fit in the ISO version.

The only issue I have with creating alignments for the DRF is having to change the evaluation of ALL of the features in the alignment to OTE and Constrain per ISO 5459. Also, some people may have trouble understanding how to convert Spatial/Planar and Origins to Primary, Secondary and Tertiary Datums.

Position - ISO.jpgPosition - ASME.jpg

[[Ma...]]

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Mainly my thoughts headed to datums.