Dimensioning in PCDMIS > SPC - Concern

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  • Dimensioning in PCDMIS > SPC - Concern

    Hey all,


    I have parts with +/-.005 and lower tolerances. Which means I have to use the 10% rule and use a .0005" or more accurate measuring tool (CMM).

    My manager is telling me if the dimension only goes three spaces (.000") then I should only dimension to only three spaces (.000") in PCDMIS.

    Here are my questions:

    Shouldn't you be dimensioning four spaces (.0000") because of the 10% rule?

    Does PCDMIS round up if using three spaces (.000")?

    Does anyone out there do this?

    I measure mostly diameters so use best fit dimensions. What do you guys think????
    I used to be high on life but I built up a tolerance.

    Brown & Sharpe Global Advantage
    PCDMIS CAD++ v2011mr2
    PH10MQ/SP600M


    sigpic

  • #2
    I would printout my results to one decimal place greater than my blueprint tolerance if at all possible and analyze the results when out of tolerance results are printed.

    H
    Hilton Roberts

    "Carpe Cerveza"

    Comment


    • #3
      3.7 MR3

      PC-DMIS will round up.
      If you have a deviation of .0006 and set dimensioning to 3 decimal places the report will show a deviation of .001.

      John
      Lately, it occurs to me
      What a long, strange trip it's been.

      2017 R1 (Offline programming)

      Comment


      • #4
        Well, it rounds 'nearest'.

        0.0001 = 0.000
        0.0002 = 0.000
        0.0003 = 0.000
        0.0004 = 0.000
        0.0005 = 0.001
        0.0006 = 0.001
        0.0007 = 0.001
        0.0008 = 0.001
        0.0009 = 0.001

        One step further:
        0.00049 = 0.000

        If he only wants you to report to 3 decimal places, it will make no difference since Pcdmis will STILL show it out of tolerance, even if it show a 0.000 out of tolerance amount. with a tol of +/-0.005, if you have an actual of 0.00549 (which will show 0.005 in 3-places) it will still give you the out of tolerance arrow and color. The only way to 'get around' that is to give it a tolerance that will only show 0.005 in 3-places, which would be something like 0.0054999999, which will show as only 0.005.
        sigpic
        Originally posted by AndersI
        I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

        Comment


        • #5
          I guess her concern is that when we start automating data collection to SPC with the control limits and all we should be matching the decimal spaces on print.
          I used to be high on life but I built up a tolerance.

          Brown & Sharpe Global Advantage
          PCDMIS CAD++ v2011mr2
          PH10MQ/SP600M


          sigpic

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