Composite FCF interpretation

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  • Composite FCF interpretation



    See the attachment.
    I would like to see if other folks here agree with my interpretation of the Composite TP FCF in the attachment. I made a sketch based on a model-based part specification.

    My interpretation:

    I setup my alignment for the top portion of the Composite FCF leveling to -D-, rotating to -E- and -F- (offset rotation) and origin on -D- and -E-.

    I dimension the TP as per the alignment.

    For the second portion of the Composite FCF, I rotate to the 4 hole pattern (bestfit, 2D, rotation only), and leave my origin at -E- and remain leveled to -D-.

    So, the only change from the DEF datum scheme is that I am no longer using -E- and -F- for rotation.

    Agree, disagree, got milk?
    Lately, it occurs to me
    What a long, strange trip it's been.

    2017 R1 (Offline programming)

  • #2
    I don't see many composite FCF's , but your interpretation seems correct.

    B&S CHAMELEON/PCDMIS CAD++ V2011

    There are no bugs, only "UNDOCUMENTED ENHANCEMENTS!"

    sigpic

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    • #3
      John you have read that correctly.

      I would like to point out that i do as you have indicated, but the software can now do it for you utilizing the Xactmeasure method of reporting. Just pointing it out.
      sigpic

      James Mannes

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      • #4
        Originally posted by JamesMannes View Post
        John you have read that correctly.

        I would like to point out that i do as you have indicated, but the software can now do it for you utilizing the Xactmeasure method of reporting. Just pointing it out.
        Yeah, I know about Exactmeasure and have used it (a customer is using 2009 and I write the programs with 3.7), but I hate the reporting that started with 4.crap.

        I wanted to get a feel for how other folks would interpret the FCF.
        The examples I have seen in various training materials do not cover that exact scheme.

        The examples I have found explain that the lower portion of the composite indicates that the holes should be measured as a pattern (this usually means using the relationship of the holes to each other as regards location).

        In this case, I see it as leaving the origin alone and only changing the orientation (rotation, or clocking).
        Last edited by John Riggins; 06-03-2010, 10:03 PM. Reason: speelink
        Lately, it occurs to me
        What a long, strange trip it's been.

        2017 R1 (Offline programming)

        Comment


        • #5
          I can't see any examples of this in my manuals either. The ones that I do see that show the lower segment with 2 datums referenced are used only to control the orientation of the pattern, say to keep the pattern parallel to an edge or something like that. I see nothing that points directly to the call out you have. This is an odd one. Doesn't seem that there is much use for DE callout over just using D.
          Ver.2009
          B&S Global

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          • #6
            I think the pattern you talk about would be without any datums in the secondary FCF, at least that is the way (I think) the book calls it out. I think you are doing it correctly with the best-fit 2-D, rotate only. They want the "spread" between the "master hole" and the 4-hole pattern to be correct, the larger, upper, primary FCF controls the "rough" location they want the pattern to remain within. So the "rotation-location" isn't as critical and the spread-relationship.
            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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            • #7
              I normally use best fit 2-D rotation only, when measuring holes equally spaced on a bolt circle.
              For this type of pattern I would thing "Rotate and translate" could be used, Am I wrong?
              sigpicIt's corona time!
              737 Xcel Cad++ v2009MR1....SE HABLA ESPAƑOL

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              • #8
                Originally posted by Roberto View Post
                I normally use best fit 2-D rotation only, when measuring holes equally spaced on a bolt circle.
                For this type of pattern I would thing "Rotate and translate" could be used, Am I wrong?

                If the E datum was not in the second FCF I would think that this would be correct, but with the E datum there you would still need to orient to that. If you do the rotate and translate you would be moving the alignment off of the E datum to balance the error in all the features. I would do rotate only.
                Saving the world, one bad part at a time.

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                • #9
                  Check the spec. Unless I am interpreting this wrong, and I'm not saying that I'm not; The Basic dimensions used to relate the PLTZF (upperframe) to specified datums are not applicable to the location of the lower frame FRTZF. If datums are specified in a lower segment they govern the rotation of the FRTZF relative to the datums and within the boundaries estabolished by the PLTZF.

                  I'm not sure that one single hole Datum E can constrain the rotation of this pattern.
                  So my question is not how he is doing his best fit, but why datum E is in the lower segment all together if it doesn't control the location of the lower segment and doesn't constrain any rotation.
                  Ver.2009
                  B&S Global

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                  • #10
                    Originally posted by John Riggins View Post
                    [ATTACH]5836[/ATTACH]

                    See the attachment.
                    I would like to see if other folks here agree with my interpretation of the Composite TP FCF in the attachment. I made a sketch based on a model-based part specification.

                    My interpretation:

                    I setup my alignment for the top portion of the Composite FCF leveling to -D-, rotating to -E- and -F- (offset rotation) and origin on -D- and -E-.

                    I dimension the TP as per the alignment.

                    For the second portion of the Composite FCF, I rotate to the 4 hole pattern (bestfit, 2D, rotation only), and leave my origin at -E- and remain leveled to -D-.

                    So, the only change from the DEF datum scheme is that I am no longer using -E- and -F- for rotation.

                    Agree, disagree, got milk?
                    Agree.

                    Comment


                    • #11
                      Originally posted by EHines View Post
                      If the E datum was not in the second FCF I would think that this would be correct, but with the E datum there you would still need to orient to that. If you do the rotate and translate you would be moving the alignment off of the E datum to balance the error in all the features. I would do rotate only.
                      Yup!

                      TK
                      sigpicHave a homebrew

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                      • #12
                        Originally posted by zerotolerance View Post
                        Check the spec. Unless I am interpreting this wrong, and I'm not saying that I'm not; The Basic dimensions used to relate the PLTZF (upperframe) to specified datums are not applicable to the location of the lower frame FRTZF. If datums are specified in a lower segment they govern the rotation of the FRTZF relative to the datums and within the boundaries estabolished by the PLTZF.

                        I'm not sure that one single hole Datum E can constrain the rotation of this pattern.
                        So my question is not how he is doing his best fit, but why datum E is in the lower segment all together if it doesn't control the location of the lower segment and doesn't constrain any rotation.

                        This is an MBD. There are no dimensions, BASIC or otherwise, other than features of size.
                        Lately, it occurs to me
                        What a long, strange trip it's been.

                        2017 R1 (Offline programming)

                        Comment


                        • #13
                          Originally posted by John Riggins View Post
                          [ATTACH]5836[/ATTACH]

                          See the attachment.
                          I would like to see if other folks here agree with my interpretation of the Composite TP FCF in the attachment. I made a sketch based on a model-based part specification.

                          My interpretation:

                          I setup my alignment for the top portion of the Composite FCF leveling to -D-, rotating to -E- and -F- (offset rotation) and origin on -D- and -E-.

                          I dimension the TP as per the alignment.

                          For the second portion of the Composite FCF, I rotate to the 4 hole pattern (bestfit, 2D, rotation only), and leave my origin at -E- and remain leveled to -D-.

                          So, the only change from the DEF datum scheme is that I am no longer using -E- and -F- for rotation.

                          Agree, disagree, got milk?
                          Agree! (2 Johns no waiting)
                          sigpic
                          I am fluent in three languages:
                          English, Sarcasm & Profanity.

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