DCC alignment is not stable

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  • DCC alignment is not stable

    I have a simple program to measure the notch steps in a car key. I do a manual alignment to locate the part in a fixture made using a universal fixturing kit. I follow this up with a DCC alignment followed by the actual feature measurements. When I remove the key and place it back onto the fixture and run the program bypassing the manual alignment, my measurement results vary by 0.1 - 0.3 millimeters.

    The program runs through the DCC alignment without stopping. I thought the DCC alignment was supposed to adjust for minor variations in part placement. If I run the manual alignment every time the variation is reduced to less than 0.02 millimeters. My engineers are now requiring me to run a manual alignment before EVERY part!

    What could I be doing wrong?

    I'm running PC-Dmis 2010 mr2 on a Hexagon retrofitted Coord 3 Bridge CMM with a PH10M.
    XANTHOFILE
    Layout Group
    Strattec Security Corp.

  • #2
    Can you maybe paste your code so that we can take a look to see what you got going?
    Sometimes we miss little things that others catch

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    • #3
      without seeing any code... it sounds like you are using a fixed location to run a manual alignment once, then every part gets put in the (roughly) same spot and does (1 only) DCC?

      Speaking just about alignments: you may want to consider doing a second alignment. Do an initial dcc alignment (perhaps an iterative?), then follow up with the actual measurement alignment you want to use.

      Think of the "initial" dcc alignment as the machine doing its own manual alignment.
      Last edited by TheyCallMeWoody; 08-20-2014, 02:42 PM.

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      • #4
        Code CODE.pdf
        XANTHOFILE
        Layout Group
        Strattec Security Corp.

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        • #5
          1. clean up your vectors so they are normalized.
          2. you should be leveling your datum plane A in DCC as soon as you measure it.
          it should be one of the first things you check in DCC.

          start there, see what happens.

          PS you can post code in the forum window using [ CODE ] [ /CODE ] tags
          Last edited by TheyCallMeWoody; 08-20-2014, 02:45 PM.

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          • #6
            I thought about that. I was hoping it might be something more basic. If nothing else works, I'll try that. Thanks
            XANTHOFILE
            Layout Group
            Strattec Security Corp.

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            • #7
              Ummm...this IS basic.

              Nothing else WILL work until you lock down your alignment.

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              • #8
                Letters (A thru Z), Numbers (0 thru 9), and the UnderscoreKey ( _ ) ONLY!

                Get out of the habit of using the "-" (minus sign key)

                PCDMIS COULD read that as a math operator. Especially when using variables.

                B&S CHAMELEON/PCDMIS CAD++ V2011

                There are no bugs, only "UNDOCUMENTED ENHANCEMENTS!"

                sigpic

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                • #9
                  Normalized all the vectors. Locked Datum A before doing the rest of the DCC points. Will find out how well that works tomorrow. Its quitting time.
                  XANTHOFILE
                  Layout Group
                  Strattec Security Corp.

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                  • #10
                    Excellent advice. Will remember that for the future and will correct it here. Thanks
                    XANTHOFILE
                    Layout Group
                    Strattec Security Corp.

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                    • #11
                      I didnt see where you re-define your -y- ? You would still be using the manual align -y- ?

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                      • #12
                        And Behold- The BASIC error I was looking for. Forgot the Y Axis in the DCC alignment. DUH! Thanks Schlag.
                        XANTHOFILE
                        Layout Group
                        Strattec Security Corp.

                        Comment


                        • #13
                          Originally posted by Schlag View Post
                          I didnt see where you re-define your -y- ? You would still be using the manual align -y- ?
                          Originally posted by XANTHOFILE View Post
                          And Behold- The BASIC error I was looking for. Forgot the Y Axis in the DCC alignment. DUH! Thanks Schlag.
                          And this is exactly why posting code is so important. That second set of eyes helps.
                          When in doubt, post code. A second set of eyes might see something you missed.
                          sigpic

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                          • #14
                            I would like to use these tags, but don't know how. I assume it would be easier than opening different software to create a .PDF to post.
                            XANTHOFILE
                            Layout Group
                            Strattec Security Corp.

                            Comment


                            • #15
                              I would like to use these tags, but don't know how. I assume it would be easier than opening different software to create a .PDF to post.
                              You just have to click on the "Go Advanced" button and you'll see the icon to place the CODE.
                              You can always hover your mouse over and icon for a description.

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