Diameter Symbol included in FCF of Squareness

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  • Diameter Symbol included in FCF of Squareness

    Good Morning all!

    I had a discussion with one of our Q.C. inspector regarding the diameter symbol which is included in the Squareness tolerance. He said that whatever the Squareess error should be doubled. He treats it like diametral Concentricty or Tru Pos., But if you calculated the angles multibly by the feature length it comes out that the error is the same as what the pcdmis is calculating it.

    Please let me know what are your opinion on this. Why do you need to include the diameter symbol to the Geometric tolerance like the Squareness?
    From what I've learn the squareness is a cylindrical tolerance zone, the feature must lie within that zone in order to call it a good part.

    Thanks to all.

  • #2
    If the toleranced feature is cylindrical (or just round), it should have a diametrical symbol included. When it is a planar surface, the zone is not cylindrical and it would not (should not) have a diametrical tolerance zone.

    I have provided a couple of links below to some GD&T sites that may explain further:

    My personal favorite: (I have taken several training classes with this guy and have a few of his books which are all awesome)...
    James D. Meadows provides Geometric Dimensioning and Tolerancing (GDT) training via on-site and public workshops, books, DVDs, per ASME Y14.5-2009, ASME Y14.5M-1994 and Y14.5-1982 Dimensioning and Tolerancing Standards. He has written three new books and a DVD training series to explain the new Y14.5-2009 standard.

    http://engr.bd.psu.edu/metbd_111/pow...pt#315,1,Slide 1
    Xcel 15-20-10 - PFXcel 7-6-5 - Merlin 11-11-7 - Romer Absolute 7525SI
    PCDMIS 2012
    Windows Office XP


    • #3
      I do not think that the results from PC-DMIS must be doubled.

      The calculated centerline of the feature must lie within a cylinder of given diameter. I do not see where this must be doubled.

      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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