Alignments

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  • Alignments

    Hello Everyone

    I have a question for all the iterative alignment users. If you want to check dimension from ABC as it relates to a blueprint (part coordinates) how do you create the ABC alignment from carbody position after an iterative alignment. Do you offset and rotate form carbody by theoreticals to the part datums or do you create an entirely new alignment ( level to A rotate to B and C and origin at A and B? I have noticed that if you just offset and rotate from carbody by the theoreticals that Datum B is not exactly 0,0 if you dimension it in the new alignment (ABC)

    Thanks for the help.

    Scott

  • #2
    I would create a new alignment to the print datums. If you offset and rotate with the theoreticals then you are not truly checking the dimensions to the datum structure, becuause theo are not actuals.
    Kevin

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    • #3
      Alignments

      Hi Kevin

      If you use the part Datums for the iterative is that not locking the datums to carbody coordinates?? If I dimension datumB in carbody coordinates it measures 0,0. Should be able to just offset and rotate back to part coordinates from carbody yes/no??

      Scott

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      • #4
        Sorry,
        I misunderstood, I thought you were creating alignment from tooling balls or fixture edges. Yes, I think theo. that if you create the iterative alignemnt from the part datums then offset and rotate to part corrdinates that it should measure 0,0.
        Kevin

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        • #5
          Are you rotating compound angles?
          Kevin

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          • #6
            Alignments

            Sometimes compound angles, sometimes just 1 angle. If there are no angles involved it seems to work fine.

            Scott

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            • #7
              I know this is obvious but the angles are probaby causing the problems. I think there was a thread about this last week. Look through the previous threads and see if you can find it. I will look when I get home and give you an update if I find it.
              Kevin

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              • #8
                I may be confused here with what you are asking but here are my two cents anyway. I always use iterative and then go in and create a alignment to the part print. I do this by checking each of the DATUMS and then align to them for a 3, 2, 1 alignment.

                By offsetting to the theo. you are setting to areas that may or may not be true to the actual DATUMS.

                I don't know as this is any help but it is my method.

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                • #9
                  Scott

                  does your car body not sit on a fixture with tooling balls
                  PC-DMIS CAD++ 4.3 MR1

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                  • #10
                    Originally posted by Tested
                    I may be confused here with what you are asking but here are my two cents anyway. I always use iterative and then go in and create a alignment to the part print. I do this by checking each of the DATUMS and then align to them for a 3, 2, 1 alignment.

                    By offsetting to the theo. you are setting to areas that may or may not be true to the actual DATUMS.

                    I don't know as this is any help but it is my method.
                    That's how I do it as well.

                    Question: do you have a math model? If so, is it in car position? If so, then the iterative alignment will align the part just as it was imported. Then, to get your print dimensions (very common....2d dimensions on print they MUST have info on) just measure the features and dimension them using the distance or location functions. One thing, make sure you are in the correct work plane or your numbers won't make sense.

                    Good luck.
                    sigpicDF

                    The "NEW AND IMPROVED" Golden Rule!

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                    • #11
                      Alignments

                      Thanks for the help guys. I agree with Tested and Dave that a seperate alignment to part datums is the best method to ensure your measurements are realted back to part datums after completing an iterative. Still not sure why there is a difference if you dimesion a measered point from the iterative alignment or from the ABC alignment when both alignments are using the same datums. The deviation on that point should be the same?? (T value)

                      Scott

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