Bonus yet again?

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  • Bonus yet again?

    Hello Folks,

    Running ver3.7mr3.

    In this version of the software, is it possible to be able to dimension a feature which is at MMC to utilize additional bonus tolerance from the datums?

    For example; I have many features dimensioned like this |1.0m|A|Bm|Cm|,
    where "A" is a leveling surface and typically "B" is a hole, and "C" is a slot.

    Matthew and Craig,

    I have tried to weed through some of the previous posts.
    I'm still not sure how to correctly set up and report out the true position to include all available bonus tolerances.

    If possible, please include an example of the methodology in your responses.

    One of our engineers is asking me if this can be done.

    Thanks in advance for your assistance.

    Blessings,
    ZydecoPete
    sigpic

  • #2
    Originally posted by Peter Warcholyk View Post
    Hello Folks,

    Running ver3.7mr3.

    In this version of the software, is it possible to be able to dimension a feature which is at MMC to utilize additional bonus tolerance from the datums?
    No. Any version before V4.1, does NOT take the material condition on the datums into account to calculate the VC (vitual condition). It always defaults your datums to RFS. So you may have been failing parts that should have passed.

    V4.1 fixes this issue. Simple to program, easy to interpret.

    But be careful, because MMC on datums can suddenly give you HUGE bonusses, depending on the lay-out of the datums. I had to revert to reporting RFS and in case of a OUTTOL, I analysed it with the VC on the datums. Almost always passes, in my case.


    Jan.
    ***************************
    PC-DMIS/NC 2010MR3; 15 December 2010; running on 18 machine tools.
    Romer Infinite; PC-DMIS 2010 MR3; 15 December 2010.

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    • #3
      Originally posted by Jan d. View Post
      I had to revert to reporting RFS and in case of a OUTTOL, I analysed it with the VC on the datums. Almost always passes, in my case.


      Jan.
      That is what I would suggest. Apparently in 3.7 with modifiers on the datums (MMC or LMC) it will act as if it is simulating a hard gage and "wiggle" things to give you results. The results will either be bad (out of tol) or perfect (.0000).

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      • #4
        You could be violating 14.5 by coding. If you do not have simultaneous requirements (you are dimensioning one feature) you may be able to get away with coding it if it is on the secondary. Like Jan said you can get into deep doo doo with the modifier on the tertiary, I would not attempt to code that.

        Craig
        <internet bumper sticker goes here>

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        • #5
          Here is the explanation of the use datums feature in PCDMIS VER 3.7 MR3.
          This was Written by Rob Jensen from B&S. It gives you several examples of how the use datums work. If the customer gives MMC<MMC<MMC on a true position then that is what they want (or allow) the part to deviate by. If you use the use datums option just know that the reported values on location (xy) will be best fitted and will not represent the actual deviation from nominal. If you need to know those then you will need to tolerance those features a second time without the use datums on, and then you will have the actuals from nominal.
          Attached Files
          Time for the Trolls to leave.

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          • #6
            Gentlemen,

            With all due respect, after reading the article concerning this issue in ver 3.7,
            I cannot see where the true position is correctly applied.

            For instance, on the following callout; Position |0.010m|A|Bm|Cm|, first of all on the particular part that I'm working on, I have 3 points at different heights for datum "A". I'm using iterative alignment on my part. I don't believe that I can create a "plane" out of these 3 points..... am I correct in this assumption.

            Regardless, after looking at the article, reference "condition 1b".
            the bonus on the feature is 0.006, the bonus on D2 & D3 is 0.003, therefore shouldn't the total be 0.010 + 0.006 + 0.003 + 0.003 = 0.022 ????

            Regards,
            ZydecoPete
            sigpic

            Comment


            • #7
              Bonus "could" be considered additional tolerance in some cases but not when applied to the datums. In the case of datums it is datum shift that gives you additional mislocation freedom. There are cases where a material condition modifier applied to a datum can end up being a one for one additional tolerance but I can not visualize it on a tertiary under any circumstances. I am not very articulate at explaining datum shift so I'll leave it to someone else. Best thing to do is picture a hard gage and the movement of the part as the datums depart in whatever direction (depending on the feature type) to allow the part to shift around on the gage. That movement is not in most cases a one for one in regards to the size difference of the datums.

              If the simple question is can I cacatenate code to the tolerance field of my dimensions, the simple answer is yes. You probably will not be legal in regards to 14.5 but you can do it.

              Craig
              <internet bumper sticker goes here>

              Comment


              • #8
                Originally posted by Peter Warcholyk View Post
                Gentlemen,

                With all due respect, after reading the article concerning this issue in ver 3.7,
                I cannot see where the true position is correctly applied.

                For instance, on the following callout; Position |0.010m|A|Bm|Cm|, first of all on the particular part that I'm working on, I have 3 points at different heights for datum "A". I'm using iterative alignment on my part. I don't believe that I can create a "plane" out of these 3 points..... am I correct in this assumption.

                Regardless, after looking at the article, reference "condition 1b".
                the bonus on the feature is 0.006, the bonus on D2 & D3 is 0.003, therefore shouldn't the total be 0.010 + 0.006 + 0.003 + 0.003 = 0.022 ????

                Regards,
                ZydecoPete
                You can create a plane out of those 3 points by creating a offset plane.Read attached doc. page 4 and it will e

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                • #9
                  Folks,

                  Thanks for your input thus far. Your insight and advice is appreciated.

                  Regards,
                  ZydecoPete
                  sigpic

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                  • #10
                    Jim,

                    I don't know how I would construct the offset plane.
                    Where is the "attached document page 4".

                    I do have a cad model. Please advise.

                    ZydecoPete
                    sigpic

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                    • #11
                      Sorry for the delay.To construct a offset plane go to you construct plane menu and go to offset plane.There will be a menu where you can enter your offsets.The document I tried to post is has a tif extension having a hard time posting it.Does anyone know how to do this.

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                      • #12
                        Jim,
                        How / where do I pull the offsets from? Currently, I use cast points created from two holes and one slot for my iterative alignment.

                        Would I use the nominals from these features, or the actuals.

                        If the actuals, then this would have to be different each time.

                        Thanks for your patience.

                        Regards,
                        ZydecoPete
                        sigpic

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                        • #13
                          You would use the nominals.Still trying to figure how to post doc.

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                          • #14
                            Peter the file is to large.E-mail me @ [email protected] & Iwill send it to you.
                            Last edited by JIM HARRIS; 11-16-2006, 11:27 AM.

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                            • #15
                              Plane with 3 points in different heights

                              Originally posted by Peter Warcholyk View Post
                              Gentlemen,

                              With all due respect, after reading the article concerning this issue in ver 3.7,
                              I cannot see where the true position is correctly applied.

                              For instance, on the following callout; Position |0.010m|A|Bm|Cm|, first of all on the particular part that I'm working on, I have 3 points at different heights for datum "A". I'm using iterative alignment on my part. I don't believe that I can create a "plane" out of these 3 points..... am I correct in this assumption.

                              Regardless, after looking at the article, reference "condition 1b".
                              the bonus on the feature is 0.006, the bonus on D2 & D3 is 0.003, therefore shouldn't the total be 0.010 + 0.006 + 0.003 + 0.003 = 0.022 ????

                              Regards,
                              ZydecoPete
                              You just construct a offset plane

                              Per

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