PC-DMIS Flipping features 180°

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  • PC-DMIS Flipping features 180°

    Hi All,
    I am currently working with PC-DMIS 2013 MR1 CAD++ and I have an issue with it flipping features.

    When I am programming the program works fine- As in it runs through features no problem when I'm programming them in.

    Once I've completed the program and then want to run it again it suddenly flips all the features or a select few.

    I have checked my vectors and they all seem fine.

    My Alignments are fine, and the CAD set up on the machine is fine too.

    I can copy and paste it into a new program and set the CAD up again and redo the exact same alignments with the same features and the program runs fine, but if I close and re-open the program I get the same issue. Sometimes I can close and re-open it 5-10 times and it's fine other times I close it once re-open it and then it happens.

    It's driving me crackers and I'm thinking it's probably some obscure little setting that I have no idea about that may have been changed before I started using the machine.

    I have the find nominal box unticked so I don't think it's that issue. I just can't seem to find the root cause of the problem.

    Any help would be much appreciated!

  • #2
    If you are aligning an origin to the midpoint of a line, then conducting a rotation within your alignment afterwards, you can easily see that 180° vector flip.
    the order of how you define alignments is absolutely paramount.
    3pt Level
    2pt Rotate
    1pt Origin
    if you follow this practice you will most likely never see the vector flipping again


    • vpt.se
      vpt.se commented
      Editing a comment
      ...or even use a measured line as an alignment feature. The direction of the line is important, which is decided by how you measure it. If you use a measured (manual) line in your alignment, make sure you measure it in the same direction every time. You should probably have noticed this though as it flips the entire alignment for you.

    • louisd
      louisd commented
      Editing a comment
      or do an alignment to origin to the start point of the line, rotate about the line.
      then do another alignment to origin to the midpoint of the line afterwards.

  • #3
    Pretty much with louisd on this one, although I've had times where my measured/actual values were not equivalent to my theoretical values. That unfortunately took a while to track down (offline run cycles won't show off ALL the same errors as online runs).

    HTH Good luck


    • #4
      I use a quick start with a readpoint- Purely to get the CMM into DCC mode as quickly as possible and, on the latest job it happened to, I used an iterative afterwards (3 points, 2 points, and 1 origin point) but all of the vectors are correct, and at first it flipped all of the features then I copied it to a new program, opened it ran it- No problem then when I opened it again yesterday to check something, 2 features had flipped and not all of them. I will try the line method though as the Axis on the CAD model are not perfect to the Axis on the machine (the X and Y are at a roughly 45° angle) But I will definitely try the line method and see what happens.

      It's just thrown me off the first lot of 2013 MR1 software I worked with never presented the problem which is why I thought it might be some kind of setting within the software.

      Thanks All!


      • Roberto
        Roberto commented
        Editing a comment
        If you want to post your code for others to review.

      • R2ah1ze1l
        R2ah1ze1l commented
        Editing a comment
        What workplane are you using, it seems if you are straddled between X/Y at 45º this could be of some concern... What makes you believe the vector is correct, seeing .7071 in both I/J feilds? Do they appropriately use direction? Roberto is correct, you should post your alignment code strategy for other to review.

    • #5
      Certain types of features ? Only 1 type or random ?


      • #6
        Originally posted by Schlag View Post
        Certain types of features ? Only 1 type or random ?
        Nope, all features after certain alignments.

        I've contacted an outside company now and their application engineers have told me there's nothing wrong with my programming, they think that maybe when I'm changing the CAD setup to match the part maybe the CMM is getting "confused" so they've sent me a document on how to actually rotate and translate the CAD model to match the CMM axis rather than matching the CMM axis to the CAD.


        • #7
          >any help would be appreciated

          Get Calypso


          • louisd
            louisd commented
            Editing a comment
            Calypso would do the same crap, if you origin and rotate to the centroid of a line that is supposed to be parallel to machine axis. You'll never get it perfectly parallel to machine axis every time you sample a part, and each time that line vector is a negative value from parallel, your vector will flip.

            Also, calypso will likely crash on you a dozen times before you actually finish writing the program. :-P

          • UseAsIs
            UseAsIs commented
            Editing a comment
            They don't call it Collapse-O for nothing lol

        • #8
          Post some code.
          PC-DMIS CAD++ 2o19 R1 SP2


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