Cylinder Alignment

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  • Cylinder Alignment

    Good Morning,
    I have an issue with an alignment. I can't put a pic on here,,,,,for legal reasons, but imagine a tube,,,,,aprox 2', holes pierced,,,,dimples in the surface from the piercing operation,,,,,and aprox 4" from the end there is an offset bend. Like a piece of electrical conduit where it comes into a junction box or any electrical box.
    Ok, I have taken an auto circle with 3 sample hits on the end, two more circles on the outside of the tube to establish a cylinder, an auto circle for the Datum B hole. If i do an interative alignment, I get an error, regardless of the tol, I have even given it 2mm and no luck.
    Then I went old school, creating the cylinder, measuring the dat b hole and doing a manual alignment, with an offset for the body alignment. I still get errors in the alignment. It skews and the rotation is out a little when I measure the offset height. I'm reverting to doing the layout on the fixture, but it prevents me from measuring the dat b and one other hole. Therefore I have to use a height gage at the end of my prg.
    What advice or suggestion are there for cylentrical alignments????

    Thanks,
    A.Gore
    PC DMIS 3.7 MR3
    sigpicA.Gore

  • #2
    With cylinder alignments you want to make sure both ends are 0,0. I usually report the circles at the ends to prove this. If it is not, you will have to rotate the centerline to the parallel axisa about the two other axis and make it the origin.

    I don't think you need an iterative alignment. These work best when using points anyway.
    I used to be high on life but I built up a tolerance.

    Brown & Sharpe Global Advantage
    PCDMIS CAD++ v2011mr2
    PH10MQ/SP600M


    sigpic

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    • #3
      Originally posted by ag162 View Post
      Good Morning,
      I have an issue with an alignment. I can't put a pic on here,,,,,for legal reasons, but imagine a tube,,,,,aprox 2', holes pierced,,,,dimples in the surface from the piercing operation,,,,,and aprox 4" from the end there is an offset bend. Like a piece of electrical conduit where it comes into a junction box or any electrical box.
      Ok, I have taken an auto circle with 3 sample hits on the end, two more circles on the outside of the tube to establish a cylinder, an auto circle for the Datum B hole. If i do an interative alignment, I get an error, regardless of the tol, I have even given it 2mm and no luck.
      Then I went old school, creating the cylinder, measuring the dat b hole and doing a manual alignment, with an offset for the body alignment. I still get errors in the alignment. It skews and the rotation is out a little when I measure the offset height. I'm reverting to doing the layout on the fixture, but it prevents me from measuring the dat b and one other hole. Therefore I have to use a height gage at the end of my prg.
      What advice or suggestion are there for cylentrical alignments????

      Thanks,
      A.Gore
      PC DMIS 3.7 MR3
      I am a little confused.
      Is Datm B Parallel to the tube? Perpendicular to the Tube? What is Datum A?
      Cylindrical Alignmnets work well with PC DMIS. You just have to follow a few rules.
      Bill Jarrells
      A lie can travel half way around the world while the truth is putting on its shoes. - Mark Twain

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      • #4
        Rudie

        Here is an example of aligning a cylinder where two holes at the end of the cylinder is needed for rotation.

        Lets say that the cylinder is lying in a y direction on your cmm.

        1.) measure the cylinder . The direction is either +y or -y.
        2.) Create new alignment and level using the cylinder in =y or -y.
        3.) Change your work plane to +y or -y and measure the 2 holes on the front
        of the cylinder. lets say hole 1 is in -x direction and hole2 in +x direction.
        4.) Create a new alignment and rotate using hole 1 and 2.
        Rotate in +x direction about +y or -Y (levelled axis)
        5.) Set the origin to required position.

        You can use this example on constructed cylinders also.

        Comment


        • #5
          Originally posted by Rudie View Post
          Here is an example of aligning a cylinder where two holes at the end of the cylinder is needed for rotation.

          Lets say that the cylinder is lying in a y direction on your cmm.

          1.) measure the cylinder . The direction is either +y or -y.
          2.) Create new alignment and level using the cylinder in =y or -y.
          3.) Change your work plane to +y or -y and measure the 2 holes on the front
          of the cylinder. lets say hole 1 is in -x direction and hole2 in +x direction.

          4.) Create a new alignment and rotate using hole 1 and 2.
          Rotate in +x direction about +y or -Y (levelled axis)
          5.) Set the origin to required position.

          You can use this example on constructed cylinders also.
          Don't forget to set the XZ Origin to the Primary Cylinder.

          This assumes the clocking holes are parallel to the primary cylinder.
          Bill Jarrells
          A lie can travel half way around the world while the truth is putting on its shoes. - Mark Twain

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          • #6
            Hello wingman,
            The dat b hole is aprox 2" from the end and the dat a & c is the tube (Cylinder).

            A.Gore
            sigpicA.Gore

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            • #7
              ag162

              I send you a pm.

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              • #8
                Originally posted by ag162 View Post
                Hello wingman,
                The dat b hole is aprox 2" from the end and the dat a & c is the tube (Cylinder).

                A.Gore
                So Dat B is Perpendicular to Dat A. Does Dat be go through (thru hole) or is it just a hole on the surface of a hollow tube?
                Bill Jarrells
                A lie can travel half way around the world while the truth is putting on its shoes. - Mark Twain

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                • #9
                  Dat B is parallel to the tube and it is a thru hole. I have set the work plane to y, which is the dir of the tube or cyl, and leveled the dat b cir to the ctr of the cyl. But when zoomed in, i could see that the alignment was skewed. I still believe that this may be caused by deformation of the tube itself.

                  Thanks,
                  A.Gore
                  sigpicA.Gore

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                  • #10
                    You cannot LEVEL to two different features.
                    Bill Jarrells
                    A lie can travel half way around the world while the truth is putting on its shoes. - Mark Twain

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                    • #11
                      Basic Desc

                      Attached is a basic description of my process. Which is in acceptance of the pc dmis application. I believe I'm using the correct process.

                      Thanks,
                      A.Gore
                      Attached Files
                      sigpicA.Gore

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                      • #12
                        Originally posted by ag162 View Post
                        Attached is a basic description of my process. Which is in acceptance of the pc dmis application. I believe I'm using the correct process.

                        Thanks,
                        A.Gore
                        OK, that is what I was thinking you had.

                        Make sure the hole (Datum B) is aligned closely with an Axis (either X or Z)
                        LEVEL to Cylinder (Y axis)
                        SET ORIGIN to Cylinder
                        Set Origin to one end of Cylinder (Plane Cylinder Intersect Point is good choice)
                        Create Point at X =0, Z = 0, and Y = nominal of hole.

                        Change Workplane to either X or Z depending on whis Axis the hole is in . The hiole is not in Y axis. The hole is perpendicular to the Cylinder

                        Measure Hole and create line from created Point to hole.
                        ROTATE about the Y Axis to Align either the X or the Z aix to this line.
                        You never want to level to two different features. Doing so invalidates the first level and keeps only the second one. Use Rotate to retain the Primary Datum.

                        Remeasure everything in DCC as the original measurements of Datum B will be suspect.

                        Re Clock to DCC Measured Features and you should be good to go.

                        I have inspected Condenser and Evaporator Manifolds using this alignment scheme and it works fine.
                        Bill Jarrells
                        A lie can travel half way around the world while the truth is putting on its shoes. - Mark Twain

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