Profile of analog scan line without CAD

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  • Profile of analog scan line without CAD

    I'm relatively new to scanning so I may be missing something obvious. What is the best way to get the profile of an analog scanned line without a CAD model? No matter what nominal/measure mode I select the theos of the hits always change making the profile relative to the learned location and not the actual theoretical location.

    For example, if I scan the top of a block that is supposed to be 3.500" the scan hit theos change closer to actual and the profile measures less than anticipated.
    Code:
    LIN2       =FEAT/CONTACT/LINE/ADAPTIVE_LINEAR_SCAN,CARTESIAN,UNBOUNDED
                THEO/<2.25,-0.25,3.5>,<1,0,0>,<0,0,1>,<0,-1,0>,0.15
                ACTL/<2.2499,-0.25,3.498>,<1,0,0.0001682>,<-0.0001682,0,1>,<0,-1,0>,0.1445
                TARG/<2.25,-0.25,3.5>,<1,0,0>,<0,0,1>,<0,-1,0>
                SHOW FEATURE PARAMETERS=YES
                  VOID DETECTION=NO
                  SURFACE1=THICKNESS_NONE,0
                  SURFACE2=THICKNESS_NONE,0
                  MEASURE MODE=NOMINALS
                  RMEAS=NONE,NONE,NONE
                  AUTO WRIST=NO
                  GRAPHICAL ANALYSIS=NO
                  FEATURE LOCATOR=NO,NO,""
                SHOW CONTACT PARAMETERS=YES
                  NUMHITS=5,DEPTH=0
                  SAMPLE METHOD=SAMPLE_HITS
                  SAMPLE HITS=0,SPACER=0,INDENT1=0,INDENT2=0
                  AVOIDANCE MOVE=NO,DISTANCE=0.3937
                SHOW HITS=YES
                  HIT/BASIC,<2.2508,-0.2545,3.4983>,<-0.0234538,0.1208771,0.9923904>,<2.2499,-0.2498,3.498>
                  HIT/BASIC,<2.2632,-0.2506,3.4985>,<-0.1689986,0.0176207,0.9854588>,<2.2565,-0.2499,3.498>
                  HIT/BASIC,<2.2705,-0.2511,3.4987>,<-0.1867219,0.0294052,0.9819726>,<2.2631,-0.2499,3.498>
                  HIT/BASIC,<2.2768,-0.2514,3.4986>,<-0.1774737,0.0403044,0.9832999>,<2.2698,-0.2498,3.498>
                  HIT/BASIC,<2.2827,-0.2508,3.4985>,<-0.1620777,0.0245799,0.9864718>,<2.2763,-0.2498,3.498>
                  HIT/BASIC,<2.2894,-0.2505,3.4985>,<-0.1642405,0.0179502,0.986257>,<2.2829,-0.2498,3.498>
                  HIT/BASIC,<2.2962,-0.2506,3.4986>,<-0.1711856,0.0180951,0.9850726>,<2.2895,-0.2499,3.498>
                  HIT/BASIC,<2.3029,-0.2508,3.4986>,<-0.1729989,0.0229138,0.9846554>,<2.2961,-0.2499,3.4979>
                  HIT/BASIC,<2.3097,-0.2504,3.4986>,<-0.178764,0.0105109,0.9838358>,<2.3027,-0.2499,3.4979>
                  HIT/BASIC,<2.316,-0.2509,3.4986>,<-0.174209,0.0237945,0.9844212>,<2.3091,-0.2499,3.498>
                  HIT/BASIC,<2.3227,-0.2504,3.4986>,<-0.1733839,0.0101306,0.9848022>,<2.3158,-0.25,3.498>
                  HIT/BASIC,<2.3294,-0.2507,3.4986>,<-0.1826991,0.021383,0.9829363>,<2.3222,-0.2499,3.498>
                  HIT/BASIC,<2.3355,-0.2504,3.4985>,<-0.1684473,0.0139062,0.9856126>,<2.3289,-0.2499,3.498>
                  HIT/BASIC,<2.3421,-0.2507,3.4986>,<-0.1700966,0.021664,0.9851892>,<2.3354,-0.2498,3.498>
                  HIT/BASIC,<2.3485,-0.2503,3.4985>,<-0.1656833,0.0115088,0.9861119>,<2.342,-0.2499,3.498>
                  HIT/BASIC,<2.355,-0.2508,3.4985>,<-0.1650265,0.0257651,0.9859525>,<2.3485,-0.2498,3.498>
                  HIT/BASIC,<2.3618,-0.2505,3.4986>,<-0.1715449,0.0167098,0.9850346>,<2.355,-0.2499,3.498>
                  HIT/BASIC,<2.3689,-0.2507,3.4987>,<-0.183317,0.020281,0.9828446>,<2.3616,-0.2499,3.498>
                  HIT/BASIC,<2.3748,-0.2504,3.4985>,<-0.1661486,0.0122129,0.9860251>,<2.3682,-0.2499,3.498>
                  HIT/BASIC,<2.3812,-0.2507,3.4985>,<-0.163234,0.0191719,0.9864011>,<2.3748,-0.2499,3.498>
                  HIT/BASIC,<2.3876,-0.2503,3.4985>,<-0.1578167,0.0114491,0.9874021>,<2.3813,-0.2499,3.498>
                  HIT/BASIC,<2.3948,-0.2507,3.4986>,<-0.1772081,0.0213446,0.9839419>,<2.3879,-0.2499,3.498>
                  HIT/BASIC,<2.4016,-0.2509,3.4987>,<-0.1830909,0.0258866,0.9827551>,<2.3944,-0.2499,3.498>
                ENDMEAS/
    DIM PROF1= PROFILE OF LINE OF LINE LIN2    FORMANDLOCATION
    AX    NOMINAL       +TOL       -TOL       MEAS        DEV     OUTTOL        MAX        MIN
    M       0.0000     0.0050     0.0000     0.0014     0.0014     0.0000     0.0007     0.0003
    The only way I could figure out how to get it relative to the real theoretical was to construct a line out of the points and define the correct theos, but even then the deviations come out opposite (shows + dev instead of -)
    Code:
    LIN3       =FEAT/LINE,CARTESIAN,UNBOUNDED,YES
                THEO/<2.25,-0.25,3.5>,<1,0,0>
                ACTL/<2.2499,-0.2499,3.498>,<1,-0.0002366,0.0001682>
                CONSTR/LINE,BF,3D,LIN2.HIT[1..LIN2.NUMHITS],,
                OUTLIER_REMOVAL/OFF,3
                FILTER/OFF,WAVELENGTH=0
    DIM PROF2= PROFILE OF LINE OF LINE LIN3    FORMANDLOCATION
    AX    NOMINAL       +TOL       -TOL       MEAS        DEV     OUTTOL        MAX        MIN
    M       0.0000     0.0050     0.0000     0.0041     0.0041     0.0000     0.0020     0.0020

  • #2
    Without CAD, I don't think there's any other way than hand/Excel-calculating the theos of a lot of vector points, measure them, group them in a set and dimension that.
    AndersI
    SW support - Hexagon Metrology Nordic AB

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    • #3
      If you are able to create (or obtain from the designer) a text file of the nominal points then you could use a freeform scan and select the "read file" option on the path definition tab.freeform.png

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