Decimal places

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  • Decimal places

    Can someone help me with this question a customer asked me....It concerns the deciaml output on the cmm reports...."how many digits is needed to create the reports with less digits, is the data Truncated or Rounding Up?"

  • #2
    F5 - Dimension - Number of Decimal Places .......... I believe they are rounded up
    sigpic

    It goes "dink" so it must be workin'

    Bollocks

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    • #3
      They are rounded nearest.

      1.00049 will report as 1.000 in 3 decimal places, 1.00051 will report as 1.001 in 3 decimal places.
      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
        Originally posted by Matthew D. Hoedeman View Post
        They are rounded nearest.

        1.00049 will report as 1.000 in 3 decimal places, 1.00051 will report as 1.001 in 3 decimal places.
        But will show OOT
        sigpic

        James Mannes

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        • #5
          Originally posted by JamesMannes View Post
          But will show OOT
          You are correct, BOTH will show OOT if the limit is 1.000

          HOWEVER, and I am NOT telling anyone to do this OR that this is right or correct in anyway....

          If you use 1.000499999999 for the tolerance, then unless the actual deviation is enough to show up as 1.001, it will not show as OOT since once it hits 1.0005 it will report as 1.001.
          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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          • #6
            Originally posted by Matthew D. Hoedeman View Post
            You are correct, BOTH will show OOT if the limit is 1.000

            HOWEVER, and I am NOT telling anyone to do this OR that this is right or correct in anyway....

            If you use 1.000499999999 for the tolerance, then unless the actual deviation is enough to show up as 1.001, it will not show as OOT since once it hits 1.0005 it will report as 1.001.


            Sad part is that there are manager types which would prefer this just so they don’t see a number that looks ‘good’ colored in red.

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            • #7
              OK..thanks but inorder to get a resolution on a Cpk, how many places should I report?...The blueprint supplied by the customer shows only three places and they are questioning the CMM's ability

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              • #8
                Never report more than the blue print calls for to a customer, it will backfire on you!!

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                • #9
                  Three decimal places in inches or mm? You can always point the customer to the cmm manufacturer's website to answer their question about the cmm's claimed accuracy.

                  Like nightrider said, my rule of thumb is measure 1 decimal place beyond what the customer drawing specifies (if possible) and report the results as the same number of decimal places the customer drawing specifies. Unless the customer requires results 1 place beyond their dwg to be reported. For example; if the dwg is inches & they only specify the dimension to one decimal place, measure it to two decimal places & report it to one.

                  Originally posted by Eric Hollenbeck View Post
                  Sad part is that there are manager types which would prefer this just so they don’t see a number that looks ‘good’ colored in red.
                  That is one reason why it is usually better to enter the cmm data into a separate layout form. Many programmers I know won't let their Enineers, let alone the customers, see the cmm printout.
                  Last edited by Slug Dawson; 01-27-2010, 05:26 PM.
                  To some the glass is half full
                  To some it is half empty
                  To me it is poorly designed by the Eng & Prod wants me to find a way to measure it in spec!

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