True Position Calcs, yet again

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  • True Position Calcs, yet again

    Ok, I know this subject has been beat to death but I need some serious (preferably) opinions on the correct way to True Position holes using 3.7 MR2

    I've attempted to attach a pic of the part and pasted the program text in here so that you can see I'm True Positioning these holes in two fashions. The first one being what my boss wants me to do and the second format being the way I've been taught to do it since I wandered off the street and into this field.

    I guess what I'd like to know for starters is which way is more accurate? Which way is the accepted generally correct way? Is there a better 3rd why that I'm not aware of yet?? Why in the H*** are the numbers in the measured column different from the first block to the second one????? That doesn't make any sense me at all.

    Someone PLEASE! explain how to use True position in PC-Demons correctly so I don't end up in Forest Park, drooling all over myself. If I haven't explained it well enough or more info is needed hollar at me and I'll try and explain the best I can.

    ok, this thing just told me I talk to much and too shorten up the post so I hope you get enough info here to do the job......


    Tom,
    ==================================================
    ================================================== =
    DCC1 =ALIGNMENT/START,RECALL:MANUAL, LIST= YES
    ALIGNMENT/LEVEL,YMINUS,PLN1-DCC
    ALIGNMENT/ROTATE,ZPLUS,TO,LIN1-DCC,ABOUT,YMINUS
    ALIGNMENT/TRANS,YAXIS,PLN1-DCC
    ALIGNMENT/TRANS,XAXIS,B-DCC
    ALIGNMENT/TRANS,ZAXIS,B-DCC
    ALIGNMENT/END
    DCC2 =ALIGNMENT/START,RECALLCC1, LIST= YES
    ALIGNMENT/TRANS_OFFSET,XAXIS,342.81
    ALIGNMENT/TRANS_OFFSET,YAXIS,-24.679
    ALIGNMENT/TRANS_OFFSET,ZAXIS,49.201
    ALIGNMENT/END
    PART =LABEL/
    COMMENT/REPT,=================================
    ,True Position of C Datum Hole
    ,
    DIM LOC34= TRUE POSITION OF CIRCLE C-DCC SD=0.000 UNITS=MM ,$
    GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH DEV PERPEN CENTERLINE=OFF DISPLAY=DIAMETER
    AX MEAS NOMINAL +TOL -TOL BONUS DEV OUTTOL
    X -333.810 -333.810 0.000
    Z 11.499 11.499 0.000
    DF 7.086 7.000 0.100 0.100 0.086 0.000 --#
    D1 PLANE PLN1-DCC AT RFS
    D2 6.560 6.500 0.100 0.100 0.160 CIRCLE B-DCC AT MMC
    TP RFS 0.140 0.137 0.000 0.000 #--
    END OF DIMENSION LOC34

    DIM LOC1= TRUE POSITION OF CIRCLE C-DCC SD=0.000 UNITS=MM ,$
    GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH DEV PERPEN CENTERLINE=OFF DISPLAY=DIAMETER
    AX MEAS NOMINAL +TOL -TOL BONUS DEV OUTTOL
    X -333.811 -333.810 -0.001
    Z 11.488 11.499 -0.011
    DF 7.086 7.000 0.100 0.100 0.086 0.000 --#
    TP RFS 0.140 0.000 0.022 0.000 #--
    END OF DIMENSION LOC1

    HOLE 4.1 =AUTO/CIRCLE,SHOWALLPARAMS = YES,SHOWHITS = NO
    THEO/-270.694,30.679,30.378,0,-1,0,6.35
    ACTL/-270.715,30.652,30.281,-0.0009162,-0.9999787,-0.0064606,6.421
    TARG/-270.694,30.679,30.378,0,-1,0
    THEO_THICKNESS = 0,RECT,IN,CIRCULAR,MAX_INSC,ONERROR = NO,$
    AUTO MOVE = BOTH,DISTANCE = 10,RMEAS = None,None,None,$
    READ POS = NO,FIND HOLE = NO,REMEASURE = NO,$
    NUMHITS = 5,INIT = 3,PERM = 3,SPACER = 2,PITCH = 0,$
    START ANG = 0,END ANG = 0,DEPTH = 1,$
    ANGLE VEC = 1,0,0
    COMMENT/REPT,=================================
    ,True Position of HOLE 4.1.
    ,
    DIM LOC35= TRUE POSITION OF CIRCLE HOLE 4.1 SD=0.000 UNITS=MM ,$
    GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH DEV PERPEN CENTERLINE=OFF DISPLAY=DIAMETER
    AX MEAS NOMINAL +TOL -TOL BONUS DEV OUTTOL
    X -271.060 -270.694 -0.366
    Z 30.670 30.378 0.292
    DF 6.421 6.350 0.100 0.100 0.071 0.000 --#
    D1 PLANE PLN1-DCC AT RFS
    D2 6.560 6.500 0.100 0.100 0.160 CIRCLE B-DCC AT MMC
    D3 7.086 7.000 0.100 0.100 0.186 CIRCLE C-DCC AT MMC
    TP RFS 0.300 0.000 0.937 0.637 -->
    END OF DIMENSION LOC35

    DIM LOC4= TRUE POSITION OF CIRCLE HOLE 4.1 SD=0.000 UNITS=MM ,$
    GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH DEV PERPEN CENTERLINE=OFF DISPLAY=DIAMETER
    AX MEAS NOMINAL +TOL -TOL BONUS DEV OUTTOL
    X -270.715 -270.694 -0.021
    Z 30.281 30.378 -0.097
    DF 6.421 6.350 0.100 0.100 0.071 0.000 --#
    TP RFS 0.300 0.000 0.198 0.000 -#-
    END OF DIMENSION LOC4

    HOLE 4.2 =AUTO/CIRCLE,SHOWALLPARAMS = YES,SHOWHITS = NO
    THEO/-287.892,41.956,-78.458,0,-1,0,6.35
    ACTL/-287.612,41.79,-78.544,-0.0016305,-0.9999986,0.0004593,6.423
    TARG/-287.892,41.956,-78.458,0,-1,0
    THEO_THICKNESS = 0,RECT,IN,CIRCULAR,MAX_INSC,ONERROR = NO,$
    AUTO MOVE = BOTH,DISTANCE = 20,RMEAS = None,None,None,$
    READ POS = NO,FIND HOLE = NO,REMEASURE = NO,$
    NUMHITS = 5,INIT = 3,PERM = 3,SPACER = 2,PITCH = 0,$
    START ANG = -1.612,END ANG = -1.612,DEPTH = 1,$
    ANGLE VEC = 1,0,0
    COMMENT/REPT,=================================
    ,True Position of HOLE 4.2
    ,
    DIM LOC38= TRUE POSITION OF CIRCLE HOLE 4.2 SD=0.000 UNITS=MM ,$
    GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH DEV PERPEN CENTERLINE=OFF DISPLAY=DIAMETER
    AX MEAS NOMINAL +TOL -TOL BONUS DEV OUTTOL
    X -287.382 -287.892 0.510
    Z -78.243 -78.458 0.215
    DF 6.423 6.350 0.100 0.100 0.073 0.000 --#
    D1 PLANE PLN1-DCC AT RFS
    D2 6.560 6.500 0.100 0.100 0.160 CIRCLE B-DCC AT MMC
    D3 7.086 7.000 0.100 0.100 0.186 CIRCLE C-DCC AT MMC
    TP RFS 0.300 0.000 1.107 0.807 -->
    END OF DIMENSION LOC38

    DIM LOC3= TRUE POSITION OF CIRCLE HOLE 4.2 SD=0.000 UNITS=MM ,$
    GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH DEV PERPEN CENTERLINE=OFF DISPLAY=DIAMETER
    AX MEAS NOMINAL +TOL -TOL BONUS DEV OUTTOL
    X -287.612 -287.892 0.280
    Z -78.544 -78.458 -0.086
    DF 6.423 6.350 0.100 0.100 0.073 0.000 --#
    TP RFS 0.300 0.000 0.587 0.287 -->
    END OF DIMENSION LOC3


    END OF DIMENSION LOC6[/SIZE]
    Last edited by TCeckels; 10-01-2008, 11:04 AM.
    sigpic
    Heading for the Badlands...


    Mitutoyo Bright Apex 916 / Renishaw PH10M / TP20 Extended Force Probe / PC-DMIS 3.7MR2

  • #2
    Where is your FCF? What are you asking?

    Comment


    • #3
      opinion on the correct way to True Position holes using 3.7 MR2: Don't,
      But if you must, never use datums and always turn perp to centerline on.
      (I plot the measured point in Catia on the model and measure the true position)
      Last edited by RussL; 11-16-2007, 06:39 AM.

      Comment


      • #4
        Code:
        ==================================================
        ================================================== =
        DCC1 =ALIGNMENT/START,RECALL:MANUAL, LIST= YES
        ALIGNMENT/LEVEL,YMINUS,PLN1-DCC
        ALIGNMENT/ROTATE,ZPLUS,TO,LIN1-DCC,ABOUT,YMINUS
        ALIGNMENT/TRANS,YAXIS,PLN1-DCC
        ALIGNMENT/TRANS,XAXIS,B-DCC
        ALIGNMENT/TRANS,ZAXIS,B-DCC
        ALIGNMENT/END
        DCC2 =ALIGNMENT/START,RECALL:DCC1, LIST= YES
        ALIGNMENT/TRANS_OFFSET,XAXIS,342.81
        ALIGNMENT/TRANS_OFFSET,YAXIS,-24.679
        ALIGNMENT/TRANS_OFFSET,ZAXIS,49.201
        ALIGNMENT/END
        PART =LABEL/
        COMMENT/REPT,=================================
        ,True Position of C Datum Hole
        , 
        DIM LOC34= TRUE POSITION OF CIRCLE C-DCC SD=0.000 UNITS=MM ,$
        GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH DEV PERPEN CENTERLINE=OFF DISPLAY=DIAMETER
        AX MEAS NOMINAL +TOL -TOL BONUS DEV OUTTOL 
        X -333.810 -333.810 0.000 
        Z 11.499 11.499 0.000 
        DF 7.086 7.000 0.100 0.100 0.086 0.000 --#
        D1 PLANE PLN1-DCC AT RFS 
        D2 6.560 6.500 0.100 0.100 0.160 CIRCLE B-DCC AT MMC 
        TP RFS 0.140 0.137 0.000 0.000 #--
        END OF DIMENSION LOC34
        
        DIM LOC1= TRUE POSITION OF CIRCLE C-DCC SD=0.000 UNITS=MM ,$
        GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH DEV PERPEN CENTERLINE=OFF DISPLAY=DIAMETER
        AX MEAS NOMINAL +TOL -TOL BONUS DEV OUTTOL 
        X -333.811 -333.810 -0.001 
        Z 11.488 11.499 -0.011 
        DF 7.086 7.000 0.100 0.100 0.086 0.000 --#
        TP RFS 0.140 0.000 0.022 0.000 #--
        END OF DIMENSION LOC1
        
        HOLE 4.1 =AUTO/CIRCLE,SHOWALLPARAMS = YES,SHOWHITS = NO
        THEO/-270.694,30.679,30.378,0,-1,0,6.35
        ACTL/-270.715,30.652,30.281,-0.0009162,-0.9999787,-0.0064606,6.421
        TARG/-270.694,30.679,30.378,0,-1,0
        THEO_THICKNESS = 0,RECT,IN,CIRCULAR,MAX_INSC,ONERROR = NO,$
        AUTO MOVE = BOTH,DISTANCE = 10,RMEAS = None,None,None,$
        READ POS = NO,FIND HOLE = NO,REMEASURE = NO,$
        NUMHITS = 5,INIT = 3,PERM = 3,SPACER = 2,PITCH = 0,$
        START ANG = 0,END ANG = 0,DEPTH = 1,$
        ANGLE VEC = 1,0,0
        COMMENT/REPT,=================================
        ,True Position of HOLE 4.1.
        , 
        DIM LOC35= TRUE POSITION OF CIRCLE HOLE 4.1 SD=0.000 UNITS=MM ,$
        GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH DEV PERPEN CENTERLINE=OFF DISPLAY=DIAMETER
        AX MEAS NOMINAL +TOL -TOL BONUS DEV OUTTOL 
        X -271.060 -270.694 -0.366 
        Z 30.670 30.378 0.292 
        DF 6.421 6.350 0.100 0.100 0.071 0.000 --#
        D1 PLANE PLN1-DCC AT RFS 
        D2 6.560 6.500 0.100 0.100 0.160 CIRCLE B-DCC AT MMC 
        D3 7.086 7.000 0.100 0.100 0.186 CIRCLE C-DCC AT MMC 
        TP RFS 0.300 0.000 0.937 0.637 -->
        END OF DIMENSION LOC35
        
        DIM LOC4= TRUE POSITION OF CIRCLE HOLE 4.1 SD=0.000 UNITS=MM ,$
        GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH DEV PERPEN CENTERLINE=OFF DISPLAY=DIAMETER
        AX MEAS NOMINAL +TOL -TOL BONUS DEV OUTTOL 
        X -270.715 -270.694 -0.021 
        Z 30.281 30.378 -0.097 
        DF 6.421 6.350 0.100 0.100 0.071 0.000 --#
        TP RFS 0.300 0.000 0.198 0.000 -#-
        END OF DIMENSION LOC4
        
        HOLE 4.2 =AUTO/CIRCLE,SHOWALLPARAMS = YES,SHOWHITS = NO
        THEO/-287.892,41.956,-78.458,0,-1,0,6.35
        ACTL/-287.612,41.79,-78.544,-0.0016305,-0.9999986,0.0004593,6.423
        TARG/-287.892,41.956,-78.458,0,-1,0
        THEO_THICKNESS = 0,RECT,IN,CIRCULAR,MAX_INSC,ONERROR = NO,$
        AUTO MOVE = BOTH,DISTANCE = 20,RMEAS = None,None,None,$
        READ POS = NO,FIND HOLE = NO,REMEASURE = NO,$
        NUMHITS = 5,INIT = 3,PERM = 3,SPACER = 2,PITCH = 0,$
        START ANG = -1.612,END ANG = -1.612,DEPTH = 1,$
        ANGLE VEC = 1,0,0
        COMMENT/REPT,=================================
        ,True Position of HOLE 4.2
        , 
        DIM LOC38= TRUE POSITION OF CIRCLE HOLE 4.2 SD=0.000 UNITS=MM ,$
        GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH DEV PERPEN CENTERLINE=OFF DISPLAY=DIAMETER
        AX MEAS NOMINAL +TOL -TOL BONUS DEV OUTTOL 
        X -287.382 -287.892 0.510 
        Z -78.243 -78.458 0.215 
        DF 6.423 6.350 0.100 0.100 0.073 0.000 --#
        D1 PLANE PLN1-DCC AT RFS 
        D2 6.560 6.500 0.100 0.100 0.160 CIRCLE B-DCC AT MMC 
        D3 7.086 7.000 0.100 0.100 0.186 CIRCLE C-DCC AT MMC 
        TP RFS 0.300 0.000 1.107 0.807 -->
        END OF DIMENSION LOC38
        
        DIM LOC3= TRUE POSITION OF CIRCLE HOLE 4.2 SD=0.000 UNITS=MM ,$
        GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH DEV PERPEN CENTERLINE=OFF DISPLAY=DIAMETER
        AX MEAS NOMINAL +TOL -TOL BONUS DEV OUTTOL 
        X -287.612 -287.892 0.280 
        Z -78.544 -78.458 -0.086 
        DF 6.423 6.350 0.100 0.100 0.073 0.000 --#
        TP RFS 0.300 0.000 0.587 0.287 -->
        END OF DIMENSION LOC3
        sigpic

        James Mannes

        Comment


        • #5
          Originally posted by RussL View Post
          opinion on the correct way to True Position holes using 3.7 MR2: Don't,
          But if you must, never use datums and always turn perp to centerline on.
          (I plot the measured point in Catia on the model and measure the true position)
          Rather a bold statement.

          If you know how to use the datums TP works quite well in PC-DMIS 3.7mr2.

          Please tell us what your FCF (Feature Control Frame) states.

          See attachment for some further help in using datums with True Position in 3.7mr2/mr3.
          Last edited by JamesMannes; 11-19-2007, 08:28 AM.
          sigpic

          James Mannes

          Comment


          • #6
            Bold statement? - Maybe,
            My biggest problem with true position with a modifier on the CMM is you need an accurate measure of the diameters involved.
            We do not get that here,
            perhaps it's because we are rarely looking at a perfectly round hole,
            perhaps it's because operators here consistantly use four hits to inspect a diameter.
            Sometimes those hits are not at 90 degree increments because of access.
            All contributes to my opinion, that we are better off staying away from true position on the CMM,
            and evaluate it after the hole diameter is more accurately measured on the bench.

            Comment


            • #7
              Originally posted by JamesMannes View Post
              Rather a bold statement.

              If you know how to use the datums TP works quite well in PC-DMIS 3.7mr2.

              Please tell us what your FCF (Feature Control Frame) states.

              See attachment for some further help in using datums with True Position in 3.7mr2/mr3.
              Like they would bad talk themselfs in there own news letter. They make it sound like there are and never have been any bugs and we all know better.

              Comment


              • #8
                Originally posted by JamesMannes View Post

                Please tell us what your FCF (Feature Control Frame) states..


                For the C Datum hole the FCF is [ 0.14 | A | Bm ]

                For the 4.1 / .2 & .3 holes it is [ 0.3 | A | Bm | Cm ]

                Looks Like I could use some instruction in pasting text on here too so it doesn't all slam up against the left side of the window......how come yours looks more organized than mine??


                Originally posted by JamesMannes View Post
                See attachment for some further help in using datums with True Position in 3.7mr2/mr3.
                I'm in the process of reading this over right now. I'll bet I'll be back with some questions later. I put in a 17 hour day yesterday so bare with me if my questions aren't as clear as they should be right off the bat. {yawnnnnn}

                Tom
                sigpic
                Heading for the Badlands...


                Mitutoyo Bright Apex 916 / Renishaw PH10M / TP20 Extended Force Probe / PC-DMIS 3.7MR2

                Comment


                • #9
                  Use this icon and then paste your copied code in between the code brackets.
                  Last edited by JamesMannes; 11-19-2007, 08:28 AM.
                  sigpic

                  James Mannes

                  Comment


                  • #10
                    Originally posted by JamesMannes View Post
                    Use this icon and then paste your copied code in between the code brackets.
                    Thanks for the leg up. Do the FCFs help determine what I'm asking / Doing wrong?
                    sigpic
                    Heading for the Badlands...


                    Mitutoyo Bright Apex 916 / Renishaw PH10M / TP20 Extended Force Probe / PC-DMIS 3.7MR2

                    Comment


                    • #11
                      Originally posted by TCeckels View Post
                      Thanks for the leg up. Do the FCFs help determine what I'm asking / Doing wrong?
                      It gives more info to us. Can't take a good look right now. I wil try in the afternoon.
                      sigpic

                      James Mannes

                      Comment


                      • #12
                        Originally posted by TCeckels View Post
                        For the C Datum hole the FCF is [ 0.14 | A | Bm ]

                        For the 4.1 / .2 & .3 holes it is [ 0.3 | A | Bm | Cm ]

                        Looks Like I could use some instruction in pasting text on here too so it doesn't all slam up against the left side of the window......how come yours looks more organized than mine??




                        I'm in the process of reading this over right now. I'll bet I'll be back with some questions later. I put in a 17 hour day yesterday so bare with me if my questions aren't as clear as they should be right off the bat. {yawnnnnn}

                        Tom
                        For your 1st FCF, we treat that as a span between -B- and -C-.

                        With regards to your second FCF, in 3.7mr2 using the "use datums" function you need a little herbage to correctly use it. When using the "use datums" option, you need to look at it like you are doing a 3-2-1 alignment. That is you first recall your feature to be dimensioned, then a planar device (covers at least 3 points for level), rotational device (covers the 2 in the alignment), and the last is your origin device (covers the 1 in the alignment). With that you should get the correct result. See attachment.

                        Anyone else have some information to add. Or, did I forget anything, mis-state anything?
                        Last edited by JamesMannes; 03-10-2008, 02:45 PM.
                        sigpic

                        James Mannes

                        Comment


                        • #13
                          Originally posted by JamesMannes View Post
                          For your 1st FCF, we treat that as a span between -B- and -C-.


                          Could you possibly elaborate on this a tick? What exactly do you mean by "treating it as a span"?


                          Originally posted by JamesMannes View Post
                          With regards to your second FCF, in 3.7mr2 using the "use datums" function you need a little herbage to correctly use it. When using the "use datums" option, you need to look at it like you are doing a 3-2-1 alignment. That is you first recall your feature to be dimensioned, then a planar device (covers at least 3 points for level), rotational device (covers the 2 in the alignment), and the last is your origin device (covers the 1 in the alignment). With that you should get the correct result. See attachment.

                          Aha....so I was doing it right in the first place and I let 'em talk me into believing I was doing it wrong. Thank You!

                          A couple questions on the attachment though......first, is there a particular reason why you chose the C datum before Choosing the B datum? You have it as Feature first, then plane, then C, then B.......I would've gone B before C but don't have a overriding reason why I'd do it that way..........

                          Second, given the control frame I shared shouldn't the B and C MMC buttons be checked in the box instead of leaving them RFS?

                          Thanks for your help and getting back to this after a weekend! I appreciate it!

                          Tom
                          sigpic
                          Heading for the Badlands...


                          Mitutoyo Bright Apex 916 / Renishaw PH10M / TP20 Extended Force Probe / PC-DMIS 3.7MR2

                          Comment


                          • #14
                            Originally posted by TCeckels View Post
                            Could you possibly elaborate on this a tick? What exactly do you mean by "treating it as a span"?





                            Aha....so I was doing it right in the first place and I let 'em talk me into believing I was doing it wrong. Thank You!

                            A couple questions on the attachment though......first, is there a particular reason why you chose the C datum before Choosing the B datum? You have it as Feature first, then plane, then C, then B.......I would've gone B before C but don't have a overriding reason why I'd do it that way..........

                            Second, given the control frame I shared shouldn't the B and C MMC buttons be checked in the box instead of leaving them RFS?

                            Thanks for your help and getting back to this after a weekend! I appreciate it!

                            Tom

                            Well, to report the -C- back to |A|B| all you have left is one axis. You more than likely are rotated to -C- and that is how you only get one axis(the axis you have rotated "to" is going to be perfect).

                            As I stated, you need to treat the features chosen for "use datums" as you would in a 3-2-1 alignment (plane, line, point).

                            You can try that route, but if I remember correctly, PC-DMIS 3.7mr2 had an issue with that. Hence, you get as close as you can by using the line feature. I believe this to be true for 3.7mr3 also.
                            sigpic

                            James Mannes

                            Comment


                            • #15
                              Originally posted by JamesMannes View Post
                              [COLOR=blue]
                              As I stated, you need to treat the features chosen for "use datums" as you would in a 3-2-1 alignment (plane, line, point).
                              ok, I had to read it a couple more times but I see what you're saying now I believe. Using the plane, line, point system there's no way to assign MMC to a plane OR a line hence RFS in D1 and D2 but I'm still not sure (other than the software not liking to do it) why I wouldn't want to go with MMC on D3 unless the point I'm missing is that D3 is treated as a point in the software and not the circular feature it is........

                              Now, the trick will be explaining to those who know everything, even though they've never run a CMM, why it works the way it does........

                              Thanks again for the help, you've helped lowered my blood pressure a good 10 points today

                              Tom
                              sigpic
                              Heading for the Badlands...


                              Mitutoyo Bright Apex 916 / Renishaw PH10M / TP20 Extended Force Probe / PC-DMIS 3.7MR2

                              Comment

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