Sheffield Endeavor R+R Question

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  • Sheffield Endeavor R+R Question

    We have just completed an ID R+R study on our Sheffield Endeavor, running PC-DMIS 4.1. The ID spec is 63.487 +/- .013. I took 35 hits with a TP-20 using a 3mm x 40mm probe. The R+R results were ~18%. My question is, does this seem typical? The R+R was completed using 5 pieces, taking 3 different readings, and calibrating in-between each user. Any advice, remarks are appreciated.

    Thanks!

  • #2
    Originally posted by jimbob View Post
    We have just completed an ID R+R study on our Sheffield Endeavor, running PC-DMIS 4.1. The ID spec is 63.487 +/- .013. I took 35 hits with a TP-20 using a 3mm x 40mm probe. The R+R results were ~18%. My question is, does this seem typical? The R+R was completed using 5 pieces, taking 3 different readings, and calibrating in-between each user. Any advice, remarks are appreciated.

    Thanks!
    Well, when doing any kind of an R&R study, alignments AND calibrations should stay the same, not be re-done for a part or an operator. Everything that you CAN keep the same should be kept the same. The only variables need to be the parts, the holding fixture and the operators. No alignments, calibrations, don't move the fixture, things like that.
    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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    • #3
      Plus and Minus 13 microns??? that is pretty tight.
      that would require a repeatability of around .002 total to get it under 10%

      Dont recal tips at anytime during R&R.
      Links to my utilities for PCDMIS

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      • #4
        My Leitz Reference can repeat better than that!

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        • #5
          Originally posted by BKulpa View Post
          My Leitz Reference can repeat better than that!
          Ok, do a 5-3-3 study, post your methods and your results or dont make comments like that.
          Links to my utilities for PCDMIS

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          • #6
            Originally posted by BKulpa View Post
            My Leitz Reference can repeat better than that!
            That's Incredible!
            Originally posted by cmmguy View Post
            Ok, do a 5-3-3 study, post your methods and your results or dont make comments like that.
            When in doubt, post code. A second set of eyes might see something you missed.
            sigpic

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            • #7
              Originally posted by John Kingston View Post
              That's Incredible!



              HAHAHAHAHAHAHAHAHAHAHAHAHAHAHA...........GOOD ONE
              sigpic.....Its called golf because all the other 4 letter words were taken

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              • #8
                OK!
                0.014mm diameter tolerance.
                10x3x3 study, ANOVA method.
                9.29% OR 0.0013MM

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                • #9
                  Not that easy... we need data and for you to describe the method that you used. Many incredible people(not implying you) post just as incredible results but dont post the true methods or data. Also when I say method I dont mean your calculations but what conditions were the tests done under. ie, fixtures, physically remove the part, 3 real different operators, etc...


                  btw .0013 range of a .014 tolerance would not yield a 9.295 GR&R. For a GR&R of .014 tolerance your number ranges should be in the .0005xx realm. So maybe this is where the methods helps with this.
                  Links to my utilities for PCDMIS

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                  • #10
                    Originally posted by cmmguy View Post
                    Not that easy... we need data and for you to describe the method that you used. Many incredible people(not implying you) post just as incredible results but dont post the true methods or data. Also when I say method I dont mean your calculations but what conditions were the tests done under. ie, fixtures, physically remove the part, 3 real different operators, etc...


                    btw .0013 range of a .014 tolerance would not yield a 9.295 GR&R. For a GR&R of .014 tolerance your number ranges should be in the .0005xx realm. So maybe this is where the methods helps with this.
                    Bubble Buster ! ! !
                    sigpic"Hated by Many, Loved by Few" _ A.B. - Stone brewery

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                    • #11
                      I used a fixture, 3 independant operators. (It took approx. 20hrs.)
                      I measured a cylinder at 8 levels 17 points per level.

                      The 0.0013 is not the range I observed; It's the total repeatability and reproducability I expect to see when using the program in a production environment.
                      Attached Files

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                      • #12
                        Originally posted by BKulpa View Post
                        I used a fixture, 3 independant operators. (It took approx. 20hrs.)
                        I measured a cylinder at 8 levels 17 points per level.

                        The 0.0013 is not the range I observed; It's the total repeatability and reproducability I expect to see when using the program in a production environment.
                        Those are pretty good numbers. But that looks like a 10x3x1 study not a 10x3x3.

                        A 10x3x3 study would yield 90 different measurements. 10 parts measured by 3 operators, 3 separate times. Removing the part from the fixture on each cycle.

                        That is why most CMM studies lean toward the 5x3x3 study.
                        Links to my utilities for PCDMIS

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