Set Datums

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  • Set Datums

    I know this is going to sound dumb but here goes.

    I took over for another guy here, and he always said that when we are using TP of a feature that we need to UN-Check the box that says "USE DATUMS" because the results were not reliable. I am alomst positive this was because he wasn't SETTING Datums. Is there a way to call a feature a datum in Ver.3.7mr3? I think that if he had been doing that then we could TP back to datums. right? In Ver.4.0 there is an "obvious" way to do this, but is there a way that I just can't find in 3.7?

    Just an FYI, we always TP back to our origin anyways, but for more complex programs where we might have numerous datums this would come in handy, cuz right now i have to create numerous new alignments and create numerous new origins to dimension this way.

    I hope this makes sense, explaining it is a PITA!!
    CMM Programmer
    Jackson Michigan
    Mistral 7.7.5
    4.3MR2

  • #2
    Previous versions did have problems with material condition modifiers for datums so he is probably like me and in the habit of not checking that box. I script in code for bonus tollerance. The problem may have been fixed by now but it is habit for me at this point.
    <internet bumper sticker goes here>

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    • #3
      YES, you CAN use the datums, and it is personal preference if you do or not. My self, I MAKE an alignment to the datums for the feature, THEN TP them in that alignment. IF the FCF says ABC, then your main alignment is what you use and no datums are needed. If you allow Pcdmis to use datums in the TP callout, you have no way of knowing FOR SURE that it did it right where as if you make the alignment, then you know it has done it right (or at elast you CAN check to see if it is right).
      sigpic
      Originally posted by AndersI
      I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

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      • #4
        I believe in V3.7, The second feature you highlight when making a TP dimension becomes first datum, etc.

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        • #5
          WMS

          I'm with Matt. I take care of the datum situation through alignment. I do not trust PCDMIS to think for me.
          <internet bumper sticker goes here>

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          • #6
            Blah, I'll have to wait until I can get 4.0 to make reports like I want em then. I really wanted to use 4.0 just for that reason, but the crappy reoprt editing wasn't worth the hassle.

            Thanks guys, as usual, I come here seeking answers......and I got em!

            Have a good weekend!
            CMM Programmer
            Jackson Michigan
            Mistral 7.7.5
            4.3MR2

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            • #7
              Good ol relationships

              For datuming, the only way I was ever able to get reliable results was the same method that you use. I create new alignments for each datuming scheme, dimension what I need to dimension and then recall the alignment that I need. As for material conditions, if I am allowed to use it (if it's called out on the print) I'll use it. Bonus, is bonus (the more tolerance the bettter).
              28 Years, 8 Months, 0 weeks and 1 Days until retirement...

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              • #8
                .....As for material conditions, if I am allowed to use it (if it's called out on the print) I'll use it. Bonus, is bonus (the more tolerance the bettter)......

                I did not say I don't use bonus I still do the bonus but not on PCDMIs's terms, I code it in. Previously PCDMIS would screw up the bunus if you had MMC for the datums, kind of like how it used to hose you when you TP'd outside the XY plane. Remember that? It was not too long ago. Like I said it may be fixed now but when you get in the habit of skirting PCDMIS's screw ups those habits kind of stick. He11 it took me a long time to warm up to cylinders and even now am still skeptical and construct when in doubt.

                Craig
                Last edited by craiger_ny; 05-05-2006, 11:38 AM.
                <internet bumper sticker goes here>

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                • #9
                  3.7MR3 is still not reliable on checking the use datums boxes. On some features it would read an axis or two right at nominal on others it would give some bogus numbers. We see most of the problems when using the datums and selecting MMC.
                  sigpic

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                  • #10
                    I'm not actually supposed to fully read and understand things before I try to make a smart comment am I???
                    28 Years, 8 Months, 0 weeks and 1 Days until retirement...

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                    • #11
                      Did I say something wrong?
                      sigpic

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                      • #12
                        No, I posted that because I did not thoroughly read craiger_ny's post and added a useless point in my post that followed his.
                        28 Years, 8 Months, 0 weeks and 1 Days until retirement...

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                        • #13
                          This text has been deleted go here for an explination.

                          Craig
                          Last edited by craiger_ny; 08-25-2006, 12:38 PM.
                          <internet bumper sticker goes here>

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                          • #14
                            I was wondering if variables would work in the dimension code. Thanks for the lesson craiger ny. I've also noticed that when you use the MMC in the use datums it will bug up the program in that area. Sometimes the only way I've been able to fix them is start a new program by cutting and pasting the good and re-writing the bad.
                            sigpic

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                            • #15
                              Yes variables and operators do work inside of dimensions. When in report mode it does not show up as an operator it displays the result only the same way comments show results in report mode rather than the operators. That is one drawback of doing it this way. Say you have a TP tolerance of 0.005 in the feature control frame on the drawing and you code in to add the bonus of a datum that is 0.0015 over the min callout. In report mode the TP tolerance is going to say 0.0065. So I guarantee that someone will come to you and say "hey, you have the wrong tolerance in here". Then you have to explain the whole bonus thingy, my favorite is when I have to explain it to the engineer that owns the very drawing the callout is from.
                              <internet bumper sticker goes here>

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