Problem? Maybe you guys can help. Not sure whats causing it.

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  • Problem? Maybe you guys can help. Not sure whats causing it.

    So Im working on a fuel cap door, in a fixture, and im having repeatability issues. Im using an sm25 scanning head with a probe change to the TP20 midprogram. There's no CAD model, program is finished and repeats with each run, but when I move the fixture/part and put it back in place I get completely different results. I set an initial manual alignment, unmarked it, then had DCC find and align to the fixture and use that alignment in running the rest of the program. Each feature Im dimensioning levels and zeros the Z axis at different scans around the fixture but when i move it and rerun, these dimensions vary each time. Any ideas?

  • #2
    you align to the fixture not to part, you should expect some deviation.
    B&S One
    PC-DMIS CAD v2014

    Romer Infinity

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    • #3
      Sure, but I aligned to the fixture just to find it. Then it aligns off the individual spots on the fixture it has to dimension from. It cant align off the part since its checking the part in relation to the fixture anyway, so why does this vary on the same part?
      Last edited by ANDREW CRAWFORD; 11-26-2014, 08:49 AM.

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      • #4
        ahh ok, what kind of dev are you getting? Even a very good fixture can easily produce dev up to .005.

        Does your fixture has 3 balls? or 3 pins?
        B&S One
        PC-DMIS CAD v2014

        Romer Infinity

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        • #5
          It has two holes that hold the door hinge and it closes on a third spot. It has to check the height of certain spots versus the flat spots on the fixture. It takes the scans okay and doesnt have any problem taking points but when the report prints I get a .010-.015 deviation, which repeats on each dimension til i move the fixture and set it again. Still repeats, just deviates on different dimensions.

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          • #6
            I also cant access the datums, either. The alignment is set off the edges of the fixture and the plate, then levels and zeros off a constructed plane using scans on the part itself (to locate again) then levels and zeros to a feature set using all the fixture scans, then levels and zeros to each of those individually when dimensioning.

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            • #7
              Can you upload a picture with the part setup on your fixture?

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              • #8
                Sure, one sec.

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                • #9
                  A complete shot in the dark, but an easy check and fix. Make sure you are not recalling your MANUAL ALIGN anywhere other than for your DCC ALIGN.

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                  • #10
                    Originally posted by ANDREW CRAWFORD View Post
                    I also cant access the datums, either. The alignment is set off the edges of the fixture and the plate, then levels and zeros off a constructed plane using scans on the part itself (to locate again) then levels and zeros to a feature set using all the fixture scans, then levels and zeros to each of those individually when dimensioning.
                    it's all good and dandy, but without a clear picture it hard to say what you doing. Post some code, and some photos
                    B&S One
                    PC-DMIS CAD v2014

                    Romer Infinity

                    Comment


                    • #11
                      Originally posted by Schlag View Post
                      A complete shot in the dark, but an easy check and fix. Make sure you are not recalling your MANUAL ALIGN anywhere other than for your DCC ALIGN.
                      true dat, I have done that in the past, ooooops. I used man align features by an accident
                      B&S One
                      PC-DMIS CAD v2014

                      Romer Infinity

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                      • #12
                        Yeah, i already went through and made sure all my other alignments recall the most recent DCC one I went with. Here are pictures:fuel door.jpg1121141512.jpg

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                        • #13
                          I can also post whatever bits of code you want, not sure what all i should put up.

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                          • #14
                            So, your datums are on the Fixture?
                            B&S One
                            PC-DMIS CAD v2014

                            Romer Infinity

                            Comment


                            • #15
                              To be honest, we need to see the whole picture: Print callout, Code
                              B&S One
                              PC-DMIS CAD v2014

                              Romer Infinity

                              Comment

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