Creating a-b datum

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  • Creating a-b datum

    I have a part that has -a- datum(dia.) on 1 end and -b- datum on the other end they are 2 different sizes. The 2 of them together create datum a-b. How can you create both datums together to use in exact meas. as a-b.

  • #2
    define your A and B datums then from the drop down in xact, select A then type a hyphen then B.

    Will look something like this when you do it.

    FCF_A-B.JPG

    Comment


    • #3
      Just got it figured out. Thanks

      Comment


      • #4
        I have a lot of parts like that. Below is an alignment I did yesterday. Figured you might like it since it fits your scenario.

        I used a 3D line through the diameters I created so i know I'm getting the whole axis that I physically probed as opposed to using cylinders (centroid-centroid)

        Code:
        CLEARP/ZPLUS,PLN_TOP.Z+0.25,ZPLUS,PLN_TOP.Z+0.25,ON
                    MOVE/POINT,NORMAL,<0,0,PLN_TOP.Z+1>
                    TIP/T1A-95B0, SHANKIJK=0, -0.9962, -0.0872, ANGLE=0
                    CLEARP/YMINUS,-1.75,ZMINUS,-3.4,ON
                    MOVE/POINT,NORMAL,<0,-1.75,1>
                    MOVE/CLEARPLANE
        RAD_G_1    =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
                    THEO/<0,0,-3.4>,<0,0,1>,2.4027,0
                    ACTL/<0,0,-3.4>,<0,0,1>,2.4027,0
                    TARG/<0,0,-3.4>,<0,0,1>
                    START ANG=182.5,END ANG=-2.5
                    ANGLE VEC=<1,0,0>
                    DIRECTION=CCW
                    SHOW FEATURE PARAMETERS=NO
                    SHOW CONTACT PARAMETERS=NO
        RAD_G_2    =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
                    THEO/<0,0,-4.075>,<0,0,1>,2.4027,0
                    ACTL/<0,0,-4.075>,<0,0,1>,2.4027,0
                    TARG/<0,0,-4.075>,<0,0,1>
                    START ANG=-2.5,END ANG=182.5
                    ANGLE VEC=<1,0,0>
                    DIRECTION=CW
                    SHOW FEATURE PARAMETERS=NO
                    SHOW CONTACT PARAMETERS=NO
        RAD_G_3    =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
                    THEO/<0,0,-4.75>,<0,0,1>,2.4027,0
                    ACTL/<0,0,-4.75>,<0,0,1>,2.4027,0
                    TARG/<0,0,-4.75>,<0,0,1>
                    START ANG=182.5,END ANG=-2.5
                    ANGLE VEC=<1,0,0>
                    DIRECTION=CCW
                    SHOW FEATURE PARAMETERS=NO
                    SHOW CONTACT PARAMETERS=NO
                    MOVE/INCREMENT,<0.25,0,0>
        RAD_H_1    =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
                    THEO/<0,0,-7.45>,<0,0,1>,2.3781,0
                    ACTL/<0,0,-7.45>,<0,0,1>,2.3781,0
                    TARG/<0,0,-7.45>,<0,0,1>
                    START ANG=-2.5,END ANG=182.5
                    ANGLE VEC=<1,0,0>
                    DIRECTION=CW
                    SHOW FEATURE PARAMETERS=NO
                    SHOW CONTACT PARAMETERS=NO
        RAD_H_2    =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
                    THEO/<0,0,-7.66>,<0,0,1>,2.3781,0
                    ACTL/<0,0,-7.66>,<0,0,1>,2.3781,0
                    TARG/<0,0,-7.66>,<0,0,1>
                    START ANG=182.5,END ANG=-2.5
                    ANGLE VEC=<1,0,0>
                    DIRECTION=CCW
                    SHOW FEATURE PARAMETERS=NO
                    SHOW CONTACT PARAMETERS=NO
                    MOVE/POINT,NORMAL,<1.425,-0.55,-7.66>
                    MOVE/POINT,NORMAL,<1.425,-0.55,2>
                    TIP/T1A-95B180, SHANKIJK=0, 0.9962, -0.0872, ANGLE=0
                    CLEARP/YPLUS,1.75,ZMINUS,-3.4,ON
                    MOVE/POINT,NORMAL,<0,1.75,1>
                    MOVE/CLEARPLANE
        RAD_G_4    =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
                    THEO/<0,0,-3.4>,<0,0,1>,2.4027,0
                    ACTL/<0,0,-3.4>,<0,0,1>,2.4027,0
                    TARG/<0,0,-3.4>,<0,0,1>
                    START ANG=177.5,END ANG=362.5
                    ANGLE VEC=<1,0,0>
                    DIRECTION=CW
                    SHOW FEATURE PARAMETERS=NO
                    SHOW CONTACT PARAMETERS=NO
        RAD_G_5    =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
                    THEO/<0,0,-4.075>,<0,0,1>,2.4027,0
                    ACTL/<0,0,-4.075>,<0,0,1>,2.4027,0
                    TARG/<0,0,-4.075>,<0,0,1>
                    START ANG=2.5,END ANG=-182.5
                    ANGLE VEC=<1,0,0>
                    DIRECTION=CCW
                    SHOW FEATURE PARAMETERS=NO
                    SHOW CONTACT PARAMETERS=NO
        RAD_G_6    =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
                    THEO/<0,0,-4.75>,<0,0,1>,2.4027,0
                    ACTL/<0,0,-4.75>,<0,0,1>,2.4027,0
                    TARG/<0,0,-4.75>,<0,0,1>
                    START ANG=177.5,END ANG=362.5
                    ANGLE VEC=<1,0,0>
                    DIRECTION=CW
                    SHOW FEATURE PARAMETERS=NO
                    SHOW CONTACT PARAMETERS=NO
                    MOVE/INCREMENT,<0.25,0,0>
        RAD_H_3    =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
                    THEO/<0,0,-7.45>,<0,0,1>,2.3781,0
                    ACTL/<0,0,-7.45>,<0,0,1>,2.3781,0
                    TARG/<0,0,-7.45>,<0,0,1>
                    START ANG=2.5,END ANG=-182.5
                    ANGLE VEC=<1,0,0>
                    DIRECTION=CCW
                    SHOW FEATURE PARAMETERS=NO
                    SHOW CONTACT PARAMETERS=NO
        RAD_H_4    =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
                    THEO/<0,0,-7.66>,<0,0,1>,2.3781,0
                    ACTL/<0,0,-7.66>,<0,0,1>,2.3781,0
                    TARG/<0,0,-7.66>,<0,0,1>
                    START ANG=177.5,END ANG=362.5
                    ANGLE VEC=<1,0,0>
                    DIRECTION=CW
                    SHOW FEATURE PARAMETERS=NO
                    SHOW CONTACT PARAMETERS=NO
        SCN1       =FEAT/SET,CARTESIAN
                    THEO/<0,0,-3.4>,<0,0,1>
                    ACTL/<0,0,-3.4>,<0,0,1>
                    CONSTR/SET,BASIC,RAD_G_1.HIT[1..5],RAD_G_4.HIT[1..5],,
        CIR_G1     =FEAT/CIRCLE,CARTESIAN,OUT,LEAST_SQR,NO
                    THEO/<0,0,-3.4>,<0,0,1>,2.4027
                    ACTL/<0,0,-3.4>,<0,0,1>,2.4027
                    CONSTR/CIRCLE,BF,2D,SCN1,,
                    OUTLIER_REMOVAL/OFF,3
                    FILTER/OFF,UPR=0
        PNT_G1     =FEAT/POINT,CARTESIAN,NO
                    THEO/<0,0,-3.4>,<0,0,1>
                    ACTL/<0,0,-3.4>,<0,0,1>
                    CONSTR/POINT,CAST,CIR_G1
        SCN4       =FEAT/SET,CARTESIAN
                    THEO/<0,0,-4.075>,<0,0,1>
                    ACTL/<0,0,-4.075>,<0,0,1>
                    CONSTR/SET,BASIC,RAD_G_2.HIT[1..5],RAD_G_5.HIT[1..5],,
        CIR_G2     =FEAT/CIRCLE,CARTESIAN,OUT,LEAST_SQR,NO
                    THEO/<0,0,-4.075>,<0,0,1>,2.4027
                    ACTL/<0,0,-4.075>,<0,0,1>,2.4027
                    CONSTR/CIRCLE,BF,2D,SCN4,,
                    OUTLIER_REMOVAL/OFF,3
                    FILTER/OFF,UPR=0
        PNT_G2     =FEAT/POINT,CARTESIAN,NO
                    THEO/<0,0,-4.075>,<0,0,1>
                    ACTL/<0,0,-4.075>,<0,0,1>
                    CONSTR/POINT,CAST,CIR_G2
        SCN7       =FEAT/SET,CARTESIAN
                    THEO/<0,0,-4.75>,<0,0,1>
                    ACTL/<0,0,-4.75>,<0,0,1>
                    CONSTR/SET,BASIC,RAD_G_3.HIT[1..5],RAD_G_6.HIT[1..5],,
        CIR_G3     =FEAT/CIRCLE,CARTESIAN,OUT,LEAST_SQR,NO
                    THEO/<0,0,-4.75>,<0,0,1>,2.4027
                    ACTL/<0,0,-4.75>,<0,0,1>,2.4027
                    CONSTR/CIRCLE,BF,2D,SCN7,,
                    OUTLIER_REMOVAL/OFF,3
                    FILTER/OFF,UPR=0
        PNT_G3     =FEAT/POINT,CARTESIAN,NO
                    THEO/<0,0,-4.75>,<0,0,1>
                    ACTL/<0,0,-4.75>,<0,0,1>
                    CONSTR/POINT,CAST,CIR_G3
        SCN10      =FEAT/SET,CARTESIAN
                    THEO/<0,0,-7.66>,<0,0,1>
                    ACTL/<0,0,-7.66>,<0,0,1>
                    CONSTR/SET,BASIC,RAD_H_2.HIT[1..5],RAD_H_4.HIT[1..5],,
        CIR_H2     =FEAT/CIRCLE,CARTESIAN,OUT,LEAST_SQR,NO
                    THEO/<0,0,-7.66>,<0,0,1>,2.3781
                    ACTL/<0,0,-7.66>,<0,0,1>,2.3781
                    CONSTR/CIRCLE,BF,2D,SCN10,,
                    OUTLIER_REMOVAL/OFF,3
                    FILTER/OFF,UPR=0
        PNT_H2     =FEAT/POINT,CARTESIAN,NO
                    THEO/<0,0,-7.66>,<0,0,1>
                    ACTL/<0,0,-7.66>,<0,0,1>
                    CONSTR/POINT,CAST,CIR_H2
        SCN13      =FEAT/SET,CARTESIAN
                    THEO/<0,0,-7.45>,<0,0,1>
                    ACTL/<0,0,-7.45>,<0,0,1>
                    CONSTR/SET,BASIC,RAD_H_1.HIT[1..5],RAD_H_3.HIT[1..5],,
        CIR_H1     =FEAT/CIRCLE,CARTESIAN,OUT,LEAST_SQR,NO
                    THEO/<0,0,-7.45>,<0,0,1>,2.3781
                    ACTL/<0,0,-7.45>,<0,0,1>,2.3781
                    CONSTR/CIRCLE,BF,2D,SCN13,,
                    OUTLIER_REMOVAL/OFF,3
                    FILTER/OFF,UPR=0
        PNT_H1     =FEAT/POINT,CARTESIAN,NO
                    THEO/<0,0,-7.45>,<0,0,1>
                    ACTL/<0,0,-7.45>,<0,0,1>
                    CONSTR/POINT,CAST,CIR_H1
                    WORKPLANE/YMINUS
        LIN_GH     =FEAT/LINE,CARTESIAN,UNBOUNDED,NO
                    THEO/<0,0,-3.4>,<0,0,-1>
                    ACTL/<0,0,-3.4>,<0,0,-1>
                    CONSTR/LINE,BF,3D,PNT_G1,PNT_G2,PNT_G3,PNT_H1,PNT_H2,,
                    OUTLIER_REMOVAL/OFF,3
                    FILTER/OFF,WAVELENGTH=0
                    WORKPLANE/ZPLUS
        A3         =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
                      ALIGNMENT/LEVEL,ZMINUS,LIN_GH
                      ALIGNMENT/TRANS,XAXIS,LIN_GH
                      ALIGNMENT/TRANS,YAXIS,LIN_GH
                      ALIGNMENT/TRANS,ZAXIS,PLN_TOP
                    ALIGNMENT/END
        Capture.PNG

        Comment


        • #5
          Because I like to measure cylindrical features as cylinders, I make compound datums to the start/end points of the datum cylinders:

          Code:
          CYL1       =FEAT/CONTACT/CYLINDER/DEFAULT,CARTESIAN,IN,LEAST_SQR
                      THEO/<0,0,0>,<0,0,1>,20,3.05
                      ACTL/<0,0,0>,<0,0,1>,20,3.05
                      TARG/<0,0,0>,<0,0,1>
                      START ANG=0,END ANG=0
                      ANGLE VEC=<0.7071068,-0.7071068,0>
                      DIRECTION=CCW
                      SHOW FEATURE PARAMETERS=NO
                      SHOW CONTACT PARAMETERS=YES
                        NUMHITS=3,NUMLEVELS=3,DEPTH=0,END OFFSET=0,PITCH=0
                        SAMPLE METHOD=SAMPLE_HITS
                        SAMPLE HITS=0,SPACER=0
                        AVOIDANCE MOVE=NO,DISTANCE=10
                        FIND HOLE=DISABLED,ONERROR=NO,READ POS=NO
                      SHOW HITS=NO
          CYL2       =FEAT/CONTACT/CYLINDER/DEFAULT,CARTESIAN,IN,LEAST_SQR
                      THEO/<0,0,30>,<0,0,1>,10,3.05
                      ACTL/<0,0,30>,<0,0,1>,10,3.05
                      TARG/<0,0,30>,<0,0,1>
                      START ANG=0,END ANG=0
                      ANGLE VEC=<0.7071068,-0.7071068,0>
                      DIRECTION=CCW
                      SHOW FEATURE PARAMETERS=NO
                      SHOW CONTACT PARAMETERS=YES
                        NUMHITS=3,NUMLEVELS=3,DEPTH=0,END OFFSET=0,PITCH=0
                        SAMPLE METHOD=SAMPLE_HITS
                        SAMPLE HITS=0,SPACER=0
                        AVOIDANCE MOVE=NO,DISTANCE=10
                        FIND HOLE=DISABLED,ONERROR=NO,READ POS=NO
                      SHOW HITS=NO
          START1     =GENERIC/POINT,DEPENDENT,CARTESIAN,$
                      NOM/XYZ,<CYL1.TSX,CYL1.TSY,CYL1.TSZ>,$
                      MEAS/XYZ,<CYL1.SX,CYL1.SY,CYL1.SZ>,$
                      NOM/IJK,<0,0,1>,$
                      MEAS/IJK,<0,0,1>
          END1       =GENERIC/POINT,DEPENDENT,CARTESIAN,$
                      NOM/XYZ,<CYL1.TEX,CYL1.TEY,CYL1.TEZ>,$
                      MEAS/XYZ,<CYL1.EX,CYL1.EY,CYL1.EZ>,$
                      NOM/IJK,<0,0,1>,$
                      MEAS/IJK,<0,0,1>
          START2     =GENERIC/POINT,DEPENDENT,CARTESIAN,$
                      NOM/XYZ,<CYL2.TSX,CYL2.TSY,CYL2.TSZ>,$
                      MEAS/XYZ,<CYL2.SX,CYL2.SY,CYL2.SZ>,$
                      NOM/IJK,<0,0,1>,$
                      MEAS/IJK,<0,0,1>
          END2       =GENERIC/POINT,DEPENDENT,CARTESIAN,$
                      NOM/XYZ,<CYL2.TEX,CYL2.TEY,CYL2.TEZ>,$
                      MEAS/XYZ,<CYL2.EX,CYL2.EY,CYL2.EZ>,$
                      NOM/IJK,<0,0,1>,$
                      MEAS/IJK,<0,0,1>
          LIN1       =FEAT/LINE,CARTESIAN,UNBOUNDED,NO
                      THEO/<0,0,-3.05>,<0,0,1>
                      ACTL/<0,0,-3.05>,<0,0,1>
                      CONSTR/LINE,BF,3D,END1,START1,END2,START2,,
                      OUTLIER_REMOVAL/OFF,3
                      FILTER/OFF,WAVELENGTH=0

          Comment


          • #6
            Originally posted by bfire85 View Post
            define your A and B datums then from the drop down in xact, select A then type a hyphen then B.

            Will look something like this when you do it.

            FCF_A-B.JPG
            Shouldn't this trick also work with concentricity? In 2019R1 is working only with position. When I try with concentricity A-B letters in edition window is red.

            Comment


            • AndersI
              AndersI commented
              Editing a comment
              I believe it's working for position and runout. Hopefully this will be more generalized in the new geometric dimensions...

          • #7
            The problem i seem to have with these compound datum is that you cannot use MMC on them. I have a cone to cone converter with datum A and B being the center of the inlet and outlet respectively. The inlet in center to the center line of the cone and the outlet is in the center but at an angle of 45 degrees. I get the compound datum A-B but the the <MC> falls away. Is this due to the fact that they not parallel to each other?

            Comment


            • Schlag
              Schlag commented
              Editing a comment
              You have 2 different sizes? If you do, which one should the software use? What if 1 is on the large size and the other is towards smaller size ? It just doesnt work out to a single value

          • #8
            It's astounding. In cases like this, I always create a line between the datum A and B, designated it as AB (for example), and chose it in the FCF. It seems the time has come to recheck all the programs and compare the results

            Comment


            • #9
              Originally posted by Vladimir View Post
              It's astounding. In cases like this, I always create a line between the datum A and B, designated it as AB (for example), and chose it in the FCF. It seems the time has come to recheck all the programs and compare the results
              I do the same... I'm using verison 2013 MR1 :| I cant type a hyphen in xact.

              Comment


              • Schlag
                Schlag commented
                Editing a comment
                Using a line is giving you the same thing. Look at the end alignment in Dans post above. You should be creating this aalignment to actually check the other features.

            • #10
              I almost finished the process of rechecking programs, in most cases the hyphen between datums is actually applied, but in one of the programs I came across an error when introducing a hyphen "compound or pattern datum not valid as tertiary datum", but if I use the old method to build a line between datums and call it AB for example, then everything works as it should, is this the problem of my version PC DMIS? I use 2012.

              1.jpg

              Comment


              • #11
                Using the hyphen combines single datum A and single datum B, making it a pattern/compound datum. Creating a line between them and using that as datum makes it a single datum (line, not compound/pattern). It has nothing to do with the PC-DMIS version, I believe you would get the same message in all versions of PC-DMIS using XactMeasure.

                If you had created A-B as a feature set, you would still get the message (as a feature set is a compound/pattern datum).
                Last edited by vpt.se; 06-24-2020, 03:13 AM.
                PC-DMIS CAD++ 2o19 R1 SP11

                Comment


                • #12
                  Originally posted by bfire85 View Post
                  define your A and B datums then from the drop down in xact, select A then type a hyphen then B.

                  Will look something like this when you do it.

                  FCF_A-B.JPG
                  When i do this, i get an error that says "The second item must be the name of a plane, cylinder, cone, or line". I'm a little confused because those are the only features im using. I am doing a perpendicularity callout. Will this method still work with perpendicularity?

                  Thanks.

                  Comment


                  • #13
                    Originally posted by ThePudds View Post

                    When i do this, i get an error that says "The second item must be the name of a plane, cylinder, cone, or line". I'm a little confused because those are the only features im using. I am doing a perpendicularity callout. Will this method still work with perpendicularity?

                    Thanks.
                    I don't think you can do an A-B on perpendicularity, unless A and B are along the same planar axis, like two concentric cylinders or two planes in the same Z axis.

                    Comment


                    • ThePudds
                      ThePudds commented
                      Editing a comment
                      Gotcha, its not. It is a plane in the Z axis and another plane in the Y axis. We ended up using a constructed line between A and B. Seems to be measuring out ok.

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