NEW ALIGNMENT - Please have a look.

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  • NEW ALIGNMENT - Please have a look.

    Datum A is Y
    Datum B is X/Z
    I rotated my alignment to Datum C X 114.3 Z -88.9

    The XYZ arrow is centered on B, flush with A. Exactly like I want it.

    I kept asking about alignments and everyone seems to rotate with a line between B and C. Or maybe rotate by the degrees of Datum C. I am not used to doing that. I like putting in the coordinates of C.

    Does anyone ever do this?
    Attached Files

  • #2
    Offsetting a basic amount from a datum is fine, but it doesn't control rotation around the Y axis. I'm guessing you have a flat bottomed part that is sitting on the surface plate or something parallel to it. If so, this is physically squaring the part up to the machine coordinate system which is tolerable if you have wide open tolerances, but it's not best practice.

    You really should be rotating the alignment to something but I can't say what without knowing anything at all about the part. If you could post a sketch(not the actual print) and/or also the beginning of the program, it might help. You can copy the text of the program and post it between code tags to format it better. Click on the underlined A and click on the # sign to add the code tags or just type it out. [CODE][/CODE]

    I'm going home for the day, but I'll be in for a few hours Saturday. Someone else here can help as well.
    PC-DMIS 2016.0 SP8

    Jeff

    Comment


    • #3
      You also put X on datum B then X on datum C.
      I agree that you must LEVEL, ROTATE. ORIGIN, in that order. I would never trust that I someone will put fixture/part perfectly square to anything.The offsets are ok as long as they are basic or target dimensions.
      Time for the Trolls to leave.

      Comment


      • #4
        What Bill said, always LEVEL, ROTATE, ORIGIN and one rule to remember is that every time you LEVEL you must ROTATE (even to a generic line/plane) of the DEMON will jack you up big time when you don't expect it

        Originally posted by William Johnson View Post
        You also put X on datum B then X on datum C.
        I agree that you must LEVEL, ROTATE. ORIGIN, in that order. I would never trust that I someone will put fixture/part perfectly square to anything.The offsets are ok as long as they are basic or target dimensions.
        Xcel & MicroVal Pfx & Global 37mr4 thru 2012mr1sp3
        Contura Calypso 5.4

        Lord, keep Your arm around my shoulder and Your hand over my mouth. Amen.

        Comment


        • #5
          Originally posted by Josh Seiden View Post
          Datum A is Y
          Datum B is X/Z
          I rotated my alignment to Datum C X 114.3 Z -88.9

          The XYZ arrow is centered on B, flush with A. Exactly like I want it.

          I kept asking about alignments and everyone seems to rotate with a line between B and C. Or maybe rotate by the degrees of Datum C. I am not used to doing that. I like putting in the coordinates of C.

          Does anyone ever do this?
          Because those are the ways to rotate to the DRF, along with basic offsets (which will happen in only 1 axis).

          What you've done is move the origin around to different places without ever rotating to anything.

          You should ask your company to send you to training.
          "This is my word... and as such is beyond contestation."

          Comment


          • Josh Seiden
            Josh Seiden commented
            Editing a comment
            How would you align the part?

          • VinniUSMC
            VinniUSMC commented
            Editing a comment
            To the DRF as defined by the print. If you post your print, or a snippet of it, I would be happy to answer.

        • #6
          Sorry to say, but that's definitely not an alignment that's going to get you repeatable results. By aligning something to the coordinates of where datum C SHOULD be, you're making the assumption that that's where it WILL be. So if you manually align to -114.3 and the center of datum C is actually at -114.5, you've already ruined any dimensions that reference the datum.

          This may work for this particular alignment on that specific part, but I wouldn't get in the habit of doing it on everything.

          Comment


          • #7
            Originally posted by VinniUSMC View Post
            You should ask your company to send you to training.
            People come to this site looking for help on something. They aren't looking to be told to go to training. When I first started in my quality lab, I wasn't aloud to go to training yet, wasn't in the budget quite yet. So what did I do, I came to this sight looking for help and some people told me the same thing. I questioned if I should even come back to the forum because of that. End of story, the guy/gal is looking for help, not to be told to go get training. What if training isn't in the cards for him/her? What if he/she has already asked and they were told no? Think about that my guy.

            Comment


            • VinniUSMC
              VinniUSMC commented
              Editing a comment
              Training is always the answer.

              That doesn't stop people here from helping. Volunteering our own time to answer questions. I don't care if it hurt your feelings to be told you need training. That's not my problem. If you have a question that I can answer, I will try to answer it. If you demonstrate a lack of understanding of some of the basic fundamentals of GD&T or CMM programming, then I will also suggest training. Being offended for others is the second worst thing wrong with humanity today.

            • ThePudds
              ThePudds commented
              Editing a comment
              VinniUSMC I wasn't offended at all. I was just stating that people don't want to here to go get training on this site. They come for help. Not to be shoved away.
              Last edited by ThePudds; 08-31-2020, 11:34 AM.

          • #8
            VinniUSMC Here's a sketch of the print view. Thank you.
            Attached Files

            Comment


            • VinniUSMC
              VinniUSMC commented
              Editing a comment
              The responses below are my suggestion as well. Rotate B to C, or construct a line with B and C and rotate to the line. Then offset rotation by the basic angle to maintain your DRF square to the print.

          • #9
            i would recommend rotating by degree about datum B

            Comment


            • Josh Seiden
              Josh Seiden commented
              Editing a comment
              Would the angle be 37.875 degrees?

            • gibsonridge
              gibsonridge commented
              Editing a comment
              yes (37.87498417)

          • #10
            Level to "A"
            Rotate to TWO CIRCLES, B & C
            Origin X & Y to "B" and Z to "A"

            Of course, there are some 'questions' that need to be covered by the customer. Do they want the rotation to be through the ACTUAL features to a NOMINAL angle (which will put any error into BOTH the X & Y axis), or do they want the "C" to be perfect in "Y"?
            sigpic
            Originally posted by AndersI
            I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

            Comment


            • VinniUSMC
              VinniUSMC commented
              Editing a comment
              If it's basic in both directions, it should be assumed to be the line B-C.

          • #11
            gibsonridge thank you. I will try this.

            Comment


            • VinniUSMC
              VinniUSMC commented
              Editing a comment
              Rotate to the line B-C, and then offset rotate by the basic angle to maintain the orientation of the DRF.

          • #12
            VinniUSMC thank you for the help.

            Comment


            • #13
              VinniUSMC
              gibsonridge

              I created a 3D line with Datum B and Datum C (Datum BC Line). Is this how you would do it? The arrows are centered on B and flush with A. It looks good.

              Attached Files

              Comment


              • gibsonridge
                gibsonridge commented
                Editing a comment
                looks good to me

            • #14
              Originally posted by Josh Seiden View Post
              VinniUSMC
              gibsonridge

              I created a 3D line with Datum B and Datum C (Datum BC Line). Is this how you would do it? The arrows are centered on B and flush with A. It looks good.
              I would make it a 2D line since both holes are IN the datum "A" plane.
              sigpic
              Originally posted by AndersI
              I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

              Comment


              • Josh Seiden
                Josh Seiden commented
                Editing a comment
                Okay, thank you.

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