Dilemma with datums

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Dilemma with datums

    What I have run into while looking into correlation issues with a customer is datum feature measurement. The parts were programmed with CAD (and using measured features) and I am not sure why or how (noms NOT from CAD this was done as I always use auto features or consrtucted feaures from individual points. I am seeing at least .001" difference in the measured results between their original program and their program with the datums feature's nomials reset to zero. This makes a huge difference between reporting the part as good or bad.

    I have tried to duplicate what they have done off the CAD model and cannot get the same numbers they have. What I am seeing in their program is nominals and vectors being different from the CAD when I pull feature off the CAD.

    Something we ran into a year and a half ago with a similar program from them was that with the noms being off is seemed to skew the alignment. Does the DEMON look at the noms of datum feature(s) and use them in the math to say where and how that feature should be used in the DRF??

    Their program code, the "Z's" and vectors are not at nom. I don't know how the targets were changed becuase when I pull feature point off that model the zero reads zero and the vectors are square.
    Code:
    DATUM-A-   =FEAT/PLANE,RECT,TRIANGLE
                THEO/0.0008,0.9069,0,-0.000024,0.0001118,1
                ACTL/0.0008,0.9069,0,-0.000024,0.0001118,1
                MEAS/PLANE,8
                HIT/BASIC,NORMAL,-1.3976,0.6606,-0.0002,-0.000024,0.0001118,1,-1.3976,0.6606,-0.0002,USE THEO = YES
                HIT/BASIC,NORMAL,-1.287,1.1577,-0.0002,-0.000024,0.0001118,1,-1.287,1.1577,-0.0002,USE THEO = YES
                HIT/BASIC,NORMAL,-0.5636,1.1438,0.0002,-0.000024,0.0001118,1,-0.5636,1.1438,0.0002,USE THEO = YES
                HIT/BASIC,NORMAL,-0.5747,0.5704,0.0003,-0.000024,0.0001118,1,-0.5747,0.5704,0.0003,USE THEO = YES
                HIT/BASIC,NORMAL,0.5562,0.5953,-0.0001,-0.000024,0.0001118,1,0.5562,0.5953,-0.0001,USE THEO = YES
                HIT/BASIC,NORMAL,0.5685,1.2403,0,-0.000024,0.0001118,1,0.5685,1.2403,0,USE THEO = YES
                HIT/BASIC,NORMAL,1.309,1.1972,-0.0001,-0.000024,0.0001118,1,1.309,1.1972,-0.0001,USE THEO = YES
                HIT/BASIC,NORMAL,1.395,0.6897,0.0001,-0.000024,0.0001118,1,1.395,0.6897,0.0001,USE THEO = YES
                ENDMEAS/
                MOVE/POINT,NORMAL,1.231,0.8999,1.235
    DATUM-B-   =FEAT/PLANE,RECT,TRIANGLE
                THEO/0.0211,0.0015,0.8361,0.0000208,0.9999969,-0.0024716
                ACTL/0.0211,0.0015,0.8361,0.0000208,0.9999969,-0.0024716
                MEAS/PLANE,8
                HIT/BASIC,NORMAL,1.2345,0.0019,0.983,0.0000208,0.9999969,-0.0024716,1.2345,0.0019,0.983,USE THEO = YES
                HIT/BASIC,NORMAL,0.851,0.0018,0.9831,0.0000208,0.9999969,-0.0024716,0.851,0.0018,0.9831,USE THEO = YES
                HIT/BASIC,NORMAL,-0.7368,0.0018,0.9833,0.0000208,0.9999969,-0.0024716,-0.7368,0.0018,0.9833,USE THEO = YES
                HIT/BASIC,NORMAL,-1.1041,0.0019,0.9833,0.0000208,0.9999969,-0.0024716,-1.1041,0.0019,0.9833,USE THEO = YES
                HIT/BASIC,NORMAL,-1.2557,0.0013,0.7171,0.0000208,0.9999969,-0.0024716,-1.2557,0.0013,0.7171,USE THEO = YES
                HIT/BASIC,NORMAL,-0.7156,0.0011,0.717,0.0000208,0.9999969,-0.0024716,-0.7156,0.0011,0.717,USE THEO = YES
                HIT/BASIC,NORMAL,0.65,0.001,0.6611,0.0000208,0.9999969,-0.0024716,0.65,0.001,0.6611,USE THEO = YES
                HIT/BASIC,NORMAL,1.2458,0.0011,0.6609,0.0000208,0.9999969,-0.0024716,1.2458,0.0011,0.6609,USE THEO = YES
                ENDMEAS/
                MOVE/POINT,NORMAL,0.9825,0.7344,0.6613
                MOVE/POINT,NORMAL,0.0095,0.8674,0.1668
    DATUM-C_L  =FEAT/PLANE,RECT,TRIANGLE
                THEO/-0.4343,0.9768,-0.11,0.9999977,0.0007264,0.0020255
                ACTL/-0.4343,0.9768,-0.11,0.9999977,0.0007264,0.0020255
                MEAS/PLANE,4
                HIT/BASIC,NORMAL,-0.4347,1.2889,-0.0154,0.9999977,0.0007264,0.0020255,-0.4347,1.2889,-0.0154,USE THEO = YES
                HIT/BASIC,NORMAL,-0.4344,0.7185,-0.0156,0.9999977,0.0007264,0.0020255,-0.4344,0.7185,-0.0156,USE THEO = YES
                HIT/BASIC,NORMAL,-0.4339,0.719,-0.2046,0.9999977,0.0007264,0.0020255,-0.4339,0.719,-0.2046,USE THEO = YES
                HIT/BASIC,NORMAL,-0.4343,1.1807,-0.2043,0.9999977,0.0007264,0.0020255,-0.4343,1.1807,-0.2043,USE THEO = YES
                ENDMEAS/
                MOVE/POINT,NORMAL,0.0137,1.0226,-0.2045
                MOVE/POINT,NORMAL,0.0137,1.0225,-0.2045
    DATUM-C_R  =FEAT/PLANE,RECT,TRIANGLE
                THEO/0.4341,0.951,-0.1154,-0.9999981,-0.0008617,0.0017278
                ACTL/0.4341,0.951,-0.1154,-0.9999981,-0.0008617,0.0017278
                MEAS/PLANE,4
                HIT/BASIC,NORMAL,0.4338,1.1547,-0.2044,-0.9999981,-0.0008617,0.0017278,0.4338,1.1547,-0.2044,USE THEO = YES
                HIT/BASIC,NORMAL,0.4342,0.7388,-0.2046,-0.9999981,-0.0008617,0.0017278,0.4342,0.7388,-0.2046,USE THEO = YES
                HIT/BASIC,NORMAL,0.4345,0.7383,-0.0263,-0.9999981,-0.0008617,0.0017278,0.4345,0.7383,-0.0263,USE THEO = YES
                HIT/BASIC,NORMAL,0.4341,1.1722,-0.0261,-0.9999981,-0.0008617,0.0017278,0.4341,1.1722,-0.0261,USE THEO = YES
                ENDMEAS/
                MOVE/POINT,NORMAL,0.1884,1.1694,-0.0261
                MOVE/POINT,NORMAL,-0.1962,-0.0101,1.353
    DATUM-C_POINT=FEAT/POINT,RECT
                THEO/0,0.9179,0.0515,-0.0000303,0.0000596,1
                ACTL/-0.0001,0.9639,-0.1127,-0.0002018,0.0007842,0.9999997
                CONSTR/POINT,MID,DATUM-C_L,DATUM-C_R
    DATUM-B_LINE=FEAT/LINE,RECT,UNBND
                THEO/-0.0036,-0.0007,0.0006,1,-0.000075,0.0000066
                ACTL/0.0109,-0.0006,0.0001,1,-0.0000207,0.000024
                CONSTR/LINE,INTOF,DATUM-B-,DATUM-A-
    AL-AUTO    =ALIGNMENT/START,RECALL:AL-MAN, LIST= YES
                ALIGNMENT/LEVEL,ZPLUS,DATUM-A-
                ALIGNMENT/ROTATE,XPLUS,TO,DATUM-B_LINE,ABOUT,ZPLUS
                ALIGNMENT/TRANS,XAXIS,DATUM-C_POINT
                ALIGNMENT/TRANS,YAXIS,DATUM-B_LINE
                ALIGNMENT/TRANS,ZAXIS,DATUM-A-
                ALIGNMENT/END
    This is their code after tweaking to CAD noms making the "Z's" all read zero and setting the vectors to CAD zero.
    Code:
    DATUM-A-   =FEAT/PLANE,RECT,OUTLINE
                THEO/0.0008,0.9076,0,0,0,1
                ACTL/0.0008,0.9076,0,0,0,1
                MEAS/PLANE,8
                HIT/BASIC,NORMAL,-1.3975,0.6612,0,0,0,1,-1.3975,0.6612,0,USE THEO = YES
                HIT/BASIC,NORMAL,-1.287,1.1583,0,0,0,1,-1.287,1.1583,0,USE THEO = YES
                HIT/BASIC,NORMAL,-0.5636,1.1445,0,0,0,1,-0.5636,1.1445,0,USE THEO = YES
                HIT/BASIC,NORMAL,-0.5746,0.5711,0,0,0,1,-0.5746,0.5711,0,USE THEO = YES
                HIT/BASIC,NORMAL,0.5562,0.596,0,0,0,1,0.5562,0.596,0,USE THEO = YES
                HIT/BASIC,NORMAL,0.5686,1.241,0,0,0,1,0.5686,1.241,0,USE THEO = YES
                HIT/BASIC,NORMAL,1.309,1.198,0,0,0,1,1.309,1.198,0,USE THEO = YES
                HIT/BASIC,NORMAL,1.3951,0.6905,0,0,0,1,1.3951,0.6905,0,USE THEO = YES
                ENDMEAS/
                MOVE/POINT,NORMAL,1.231,0.8987,1.235
    DATUM-B-   =FEAT/PLANE,RECT,OUTLINE
                THEO/0.0212,0,0.8355,0,1,0
                ACTL/0.0212,0,0.8355,0,1,0
                MEAS/PLANE,8
                HIT/BASIC,NORMAL,1.2346,0,0.9824,0,1,0,1.2346,0,0.9824,USE THEO = YES
                HIT/BASIC,NORMAL,0.8511,0,0.9825,0,1,0,0.8511,0,0.9825,USE THEO = YES
                HIT/BASIC,NORMAL,-0.7367,0,0.9828,0,1,0,-0.7367,0,0.9828,USE THEO = YES
                HIT/BASIC,NORMAL,-1.104,0,0.9827,0,1,0,-1.104,0,0.9827,USE THEO = YES
                HIT/BASIC,NORMAL,-1.2557,0,0.7165,0,1,0,-1.2557,0,0.7165,USE THEO = YES
                HIT/BASIC,NORMAL,-0.7155,0,0.7164,0,1,0,-0.7155,0,0.7164,USE THEO = YES
                HIT/BASIC,NORMAL,0.6501,0,0.6605,0,1,0,0.6501,0,0.6605,USE THEO = YES
                HIT/BASIC,NORMAL,1.2459,0,0.6603,0,1,0,1.2459,0,0.6603,USE THEO = YES
                ENDMEAS/
                MOVE/POINT,NORMAL,0.9825,0.7332,0.6613
                MOVE/POINT,NORMAL,0.0095,0.8662,0.1668
    DATUM-C_L  =FEAT/PLANE,RECT,OUTLINE
                THEO/-0.4345,0.9775,-0.11,1,0,0
                ACTL/-0.4345,0.9775,-0.11,1,0,0
                MEAS/PLANE,4
                HIT/BASIC,NORMAL,-0.4345,1.2896,-0.0152,1,0,0,-0.4345,1.2896,-0.0152,USE THEO = YES
                HIT/BASIC,NORMAL,-0.4345,0.7192,-0.0158,1,0,0,-0.4345,0.7192,-0.0158,USE THEO = YES
                HIT/BASIC,NORMAL,-0.4345,0.7198,-0.2048,1,0,0,-0.4345,0.7198,-0.2048,USE THEO = YES
                HIT/BASIC,NORMAL,-0.4345,1.1815,-0.2042,1,0,0,-0.4345,1.1815,-0.2042,USE THEO = YES
                ENDMEAS/
                MOVE/POINT,NORMAL,0.0137,1.0213,-0.2045
                MOVE/POINT,NORMAL,0.0137,1.0213,-0.2045
    DATUM-C_R  =FEAT/PLANE,RECT,OUTLINE
                THEO/0.4345,0.9518,-0.1154,-1,0,0
                ACTL/0.4345,0.9518,-0.1154,-1,0,0
                MEAS/PLANE,4
                HIT/BASIC,NORMAL,0.4345,1.1556,-0.2043,-1,0,0,0.4345,1.1556,-0.2043,USE THEO = YES
                HIT/BASIC,NORMAL,0.4345,0.7396,-0.2048,-1,0,0,0.4345,0.7396,-0.2048,USE THEO = YES
                HIT/BASIC,NORMAL,0.4345,0.739,-0.0264,-1,0,0,0.4345,0.739,-0.0264,USE THEO = YES
                HIT/BASIC,NORMAL,0.4345,1.173,-0.026,-1,0,0,0.4345,1.173,-0.026,USE THEO = YES
                ENDMEAS/
                MOVE/POINT,NORMAL,0.1884,1.1681,-0.0261
                MOVE/POINT,NORMAL,-0.1962,-0.0113,1.353
    DATUM-C_POINT=FEAT/POINT,RECT
                THEO/0,0.9647,-0.1127,0,0,1
                ACTL/0,0.9647,-0.1127,0.0000067,-0.0005882,0.9999998
                CONSTR/POINT,MID,DATUM-C_L,DATUM-C_R
    DATUM-B_LINE=FEAT/LINE,RECT,UNBND
                THEO/0,0,0,1,0,0
                ACTL/0.011,0,0,1,0,0
                CONSTR/LINE,INTOF,DATUM-B-,DATUM-A-
    AL-AUTO    =ALIGNMENT/START,RECALL:AL-MAN, LIST= YES
                ALIGNMENT/LEVEL,ZPLUS,DATUM-A-
                ALIGNMENT/ROTATE,XPLUS,TO,DATUM-B_LINE,ABOUT,ZPLUS
                ALIGNMENT/TRANS,XAXIS,DATUM-C_POINT
                ALIGNMENT/TRANS,YAXIS,DATUM-B_LINE
                ALIGNMENT/TRANS,ZAXIS,DATUM-A-
                ALIGNMENT/END
    Last edited by dwade; 06-04-2014, 03:31 PM.
    Xcel & MicroVal Pfx & Global 37mr4 thru 2012mr1sp3
    Contura Calypso 5.4

    Lord, keep Your arm around my shoulder and Your hand over my mouth. Amen.

  • #2
    Your AL-AUTO commands are different; different alignment recall, different rotate, different yaxis.

    Comment


    • #3
      Yes, I forgot to change that back before the paste, I had played with the alignments trying to get different results. You can ignore that, my apologies
      Xcel & MicroVal Pfx & Global 37mr4 thru 2012mr1sp3
      Contura Calypso 5.4

      Lord, keep Your arm around my shoulder and Your hand over my mouth. Amen.

      Comment


      • #4
        Did you re-execute the alignment after tweaking the vectors?

        Comment


        • #5
          Originally posted by N3WPV View Post
          Did you re-execute the alignment after tweaking the vectors?
          I created a second program with the original alignment then a third program with the tweaked alignment.
          Xcel & MicroVal Pfx & Global 37mr4 thru 2012mr1sp3
          Contura Calypso 5.4

          Lord, keep Your arm around my shoulder and Your hand over my mouth. Amen.

          Comment


          • #6
            I use to tell my customers "If you lie to PC-DMIS (i.e. don't enter correct THEOs), then PC-DMIS will happily lie back to you in the results!" ...
            AndersI
            SW support - Hexagon Metrology Nordic AB

            Comment


            • #7
              Originally posted by AndersI View Post
              I use to tell my customers "If you lie to PC-DMIS (i.e. don't enter correct THEOs), then PC-DMIS will happily lie back to you in the results!" ...
              That is what I am thinking. Without knowing how the calculations are used against the model, I would assume that the software compares the actuals against the nominals and says "this is how I am supposed to oriented and located" and levels/origins accordingly.
              Last edited by dwade; 06-05-2014, 08:32 AM.
              Xcel & MicroVal Pfx & Global 37mr4 thru 2012mr1sp3
              Contura Calypso 5.4

              Lord, keep Your arm around my shoulder and Your hand over my mouth. Amen.

              Comment


              • #8
                One of the 10,000 things commonly forgotten from the 101 class is:
                When using Measured Features, always go back and correct all nominal XYZ and IJK values for everything to print/CAD nominal or your DRFs will be off.

                We recently changed our course structure to allow the students to start using CAD right away, because of the high rate of students whose retention rate hit the full mark after they learned to make features with the jogbox but before CAD was introduced. If I had a nickel for every sloppy measured-feature alignment I've seen...

                Good luck with the battle, Dwade.

                Comment

                Related Topics

                Collapse

                Working...
                X