Constructed cylinder is skewed???

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  • Constructed cylinder is skewed???

    Hi Guys,

    I have a cylindrical part on a V-block. Datum A is Cylinder OD (250mm long), constructed in y- direction. I am then constructing another cylinder on a bore from two diameters only 3.5mm apart. The first cylinder constructs and makes sense but the 2nd cylinder reads a length of 15.6mm and x and z vectors are out plus the visual shows the cylinder on an angle. I'm a bit confused as to why?



    =FEAT/CYLINDER,CARTESIAN,IN,LEAST_SQR,NO
    THEO/<0.001,2.75,-0.014>,<0,1,0>,147.02,3.5
    ACTL/<1.95,-26.676,-0.608>,<0.0195694,0.9966178,0.0798119>,146.78,15.6 15
    CONSTR/CYLINDER,BF,ID_147_C,ID_147_A,,
    COMMENT/READOUTS,NO,


    Any help appreciated.

    Cheers.

  • #2
    The theoreticals for XYZ look a bit off, unless the cylinder is supposed to be .001,.014 from center. This leads me to believe the theoreticals for the two circles aren't quite right. How are they created, as measured features or as autocircles?

    This should make no difference, but what if you do this:

    CONSTR/CYLINDER,BF,ID_147_C.HIT[1..ID_147_C.NUMHITS],ID_147_A.HIT[1..ID_147_A.NUMHITS],,

    Comment


    • dph51
      dph51 commented
      Editing a comment
      +1

      Accessing the hits should work.

  • #3
    They are auto circles. The cylinder theo shouldn't be off?? The circle theo seem okay. I have tried it with the can sat on bed in z+ and still same issue?

    Comment


    • #4
      Is there a minimum height between two circles that a cylinder will struggle to accurately construct?

      Comment


      • RandomJerk
        RandomJerk commented
        Editing a comment
        What's the roundness of the two circles you're using?

    • #5
      Try adding a third circle. PCDmis has always struggled with only two levels when constructing a cylinder. There are a bunch of threads about cylinder construction on here. Do a search.
      You can never tell exactly how deep a mud puddle is without getting your feet wet -- Dennis the Menice

      Comment


      • #6
        mode/dcc
        pln2 =feat/contact/plane/default,cartesian,outline,least_sqr
        theo/<0,0,0>,<0,0,1>
        actl/<0.0006,0.0036,0.0027>,<-0.0001828,-0.0004453,0.9999999>
        targ/<0,0,0>,<0,0,1>
        angle vec=<1,0,0>,radial
        show feature parameters=no
        show contact parameters=yes
        numhits=5,numrings=1
        spacer=74
        avoidance move=no,distance=10
        show hits=no
        cir2 =feat/contact/circle/default,cartesian,in,least_sqr
        theo/<0,0,-15>,<0,0,1>,145.6
        actl/<0.0513,-0.1908,-15>,<0,0,1>,145.6382
        targ/<0,0,-15>,<0,0,1>
        start ang=0,end ang=360
        angle vec=<1,0,0>
        direction=ccw
        show feature parameters=no
        show contact parameters=yes
        numhits=7,depth=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
        a2 =alignment/start,recall:a1,list=yes
        alignment/level,zplus,pln2
        alignment/trans,zaxis,pln2
        alignment/trans,xaxis,cir2
        alignment/trans,yaxis,cir2
        alignment/end
        cir3 =feat/contact/circle/default,cartesian,in,least_sqr
        theo/<0,0,-2.5>,<0,0,1>,147.02
        actl/<-0.0003,0.0042,-2.5>,<0,0,1>,147.0294
        targ/<0,0,-2.5>,<0,0,1>
        start ang=0,end ang=360
        angle vec=<1,0,0>
        direction=ccw
        show feature parameters=no
        show contact parameters=yes
        numhits=11,depth=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
        a3 =alignment/start,recall:a2,list=yes
        alignment/level,zplus,pln2
        alignment/trans,zaxis,pln2
        alignment/trans,xaxis,cir3
        alignment/trans,yaxis,cir3
        alignment/end
        cir4 =feat/contact/circle/default,cartesian,in,least_sqr
        theo/<0,0,-0.75>,<0,0,1>,147.02
        actl/<0.0004,0.0033,-0.75>,<0,0,1>,147.0364
        targ/<0,0,-0.75>,<0,0,1>
        start ang=0,end ang=360
        angle vec=<1,0,0>
        direction=ccw
        show feature parameters=no
        show contact parameters=yes
        numhits=13,depth=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
        cir5 =feat/contact/circle/default,cartesian,in,least_sqr
        theo/<0,0,-2.5>,<0,0,1>,147.02
        actl/<0.0004,-0.0001,-2.5>,<0,0,1>,147.0301
        targ/<0,0,-2.5>,<0,0,1>
        start ang=0,end ang=360
        angle vec=<1,0,0>
        direction=ccw
        show feature parameters=no
        show contact parameters=yes
        numhits=13,depth=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
        cir6 =feat/contact/circle/default,cartesian,in,least_sqr
        theo/<0,0,-4.5>,<0,0,1>,147.02
        actl/<0.001,0.0006,-4.5>,<0,0,1>,147.0277
        targ/<0,0,-4.5>,<0,0,1>
        start ang=0,end ang=360
        angle vec=<1,0,0>
        direction=ccw
        show feature parameters=no
        show contact parameters=yes
        numhits=13,depth=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
        cyl1 =feat/cylinder,cartesian,in,least_sqr,yes
        theo/<0,0,-3.375>,<0,0,1>,147.02,3.75
        actl/<0.0018,-0.0055,-2.6663>,<0.0143058,-0.0787143,-0.9967946>,146.7957,15.4207
        constr/cylinder,bf,cir4,cir5,cir6,,

        dim loc1= location of circle cir4 units=mm ,$
        graph=off text=off mult=10.00 output=both half angle=no
        ax meas nominal dev +tol -tol outtol
        x 0.0004 0.0000 0.0004 0.0000 0.0000 0.0004 -------->
        y 0.0033 0.0000 0.0033 0.0000 0.0000 0.0033 -------->
        d 147.0364 147.0200 0.0164 0.0000 0.0000 0.0164 -------->
        rn 0.3617 0.0000 0.3617 0.0000 0.0000 0.3617 -------->
        end of dimension loc1
        dim loc2= location of circle cir5 units=mm ,$
        graph=off text=off mult=10.00 output=both half angle=no
        ax meas nominal dev +tol -tol outtol
        x 0.0004 0.0000 0.0004 0.0000 0.0000 0.0004 -------->
        y -0.0001 0.0000 -0.0001 0.0000 0.0000 0.0001 <--------
        d 147.0301 147.0200 0.0101 0.0000 0.0000 0.0101 -------->
        rn 0.3579 0.0000 0.3579 0.0000 0.0000 0.3579 -------->
        end of dimension loc2
        dim loc3= location of circle cir6 units=mm ,$
        graph=off text=off mult=10.00 output=both half angle=no
        ax meas nominal dev +tol -tol outtol
        x 0.0010 0.0000 0.0010 0.0000 0.0000 0.0010 -------->
        y 0.0006 0.0000 0.0006 0.0000 0.0000 0.0006 -------->
        d 147.0277 147.0200 0.0077 0.0000 0.0000 0.0077 -------->
        rn 0.3558 0.0000 0.3558 0.0000 0.0000 0.3558 -------->
        end of dimension loc3
        dim loc4= location of cylinder cyl1 units=mm ,$
        graph=off text=off mult=10.00 output=both half angle=no
        ax meas nominal dev +tol -tol outtol
        x 0.0018 0.0000 0.0018 0.0500 0.0500 0.0000 ----#----
        y -0.0055 0.0000 -0.0055 0.0500 0.0500 0.0000 ----#----
        d 146.7957 147.0200 -0.2243 0.0500 0.0500 0.1743 <--------
        end of dimension loc4

        Comment


        • #7
          Above is just a quick test program with can sat on bed.

          Comment


          • #8
            Try changing to

            Code:
            [B]cyl1 =feat/cylinder,cartesian,in,least_sqr,yes
            theo/<0,0,-3.375>,<0,0,1>,147.02,3.75
            actl/<0.0018,-0.0055,-2.6663>,<0.0143058,-0.0787143,-0.9967946>,146.7957,15.4207
            [COLOR=#FF0000]constr/cylinder,bf,cir4.HIT[1..cir4.NUMHITS],cir5.HIT[1..cir5.NUMHITS],cir6.HIT [1..cir6.NUMHITS],[/COLOR],[/B]
            Last edited by dph51; 10-27-2017, 10:18 AM. Reason: left off ".HIT" Thanks RJ

            B&S CHAMELEON/PCDMIS CAD++ V2011

            There are no bugs, only "UNDOCUMENTED ENHANCEMENTS!"

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            • #9
              Cyl1 =feat/cylinder,cartesian,in,least_sqr,yes
              theo/<0,0,-2.625>,<0,0,-1>,147.02,3.75
              actl/<1.7866,-4.8599,-2.6212>,<-0.0266581,-0.0105757,-0.9995887>,10.3593,3.7485
              constr/cylinder,bf,cir4[1..cir4.numhits],cir5 [1..cir5.numhits],cir6[1..cir6.numhits],,

              Comment


              • #10
                I'm not quite sure what the 'numhits' feature does. My cylinder is reading correct length but i don't understand the actual dims and diameter of cylinder?

                Comment


                • RandomJerk
                  RandomJerk commented
                  Editing a comment
                  you're missing something there, you've got cir4[1..cir4.numhits], it should be cir4.HIT[1..cir4.numhits]

                  What that does is force it to use the actual hits of the feature to do the construction. the notation [1..CIR4.NUMHITS} tells it to use hit #1 through the total NUMber of HITS in the feature. If you took 8 hits, it could say [1..8], but if you ever changed the number of hits in the feature you'd have to change this, also. by using NUMHITS, you can change it in the feature to your heart's content and not have to update.

                • dph51
                  dph51 commented
                  Editing a comment
                  RJ Thanks for spotting my mistake. These tired old eyes missed that ".HIT"

              • #11
                Hi guys, been on holiday shutdown for a week. First day back.... Doom and Gloom!! Thanks for the replies. Corrected the .HIT and it has skewed my cylinder again?

                CYL1 =FEAT/CYLINDER,CARTESIAN,IN,LEAST_SQR,YES
                THEO/<0,0,-2.625>,<0,0,-1>,147.02,3.75
                ACTL/<0.0029,-0.004,-2.655>,<0.0153082,-0.0786107,-0.9967879>,146.7978,15.4427
                CONSTR/CYLINDER,BF,CIR4.HIT[1..CIR4.NUMHITS],CIR5.HIT[1..CIR5.NUMHITS],CIR6.HIT[1..CIR6.NUMHITS],,


                Any ideas?

                Comment

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