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Thread: Is it legal to use a Centerline as a Datum Feature?

  1. #1
    Associate Engineer
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    Is it legal to use a Centerline as a Datum Feature?

    Hi Guys, I'm new in this forum and I just want to know if you can clarify some doubts that I have with the attached drawing:

    1. The Datum Feature A is a centerline, is that legal?
    2. There are two Basic Dimensions (2.050 and 1.865) from hole to hole with the work "SET". Does anyone know what SET mean? Is it the same as Datum Target?

    I will appreciate your help in this matter.

    Thanks!!!
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    Last edited by Kelly Bramble; 06-30-2014 at 07:41 AM.

  2. #2
    Administrator Kelly Bramble's Avatar
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    Quote Originally Posted by Larat View Post

    1. The Datum Feature A is a centerline, is that legal?
    Absolutely not!

    Datum symbols may NOT be applied to center lines, center planes, or axes.

    References:

    ASME Y14.5-2009, para. 4.8.2 (page 57)

    ANSI Y14.5M-1994, para 4.3.2 (page 52)

    It is likely that the drawing standard of the drawing you attached is ANSI 14.5M-1982 or earlier.

    ANSI Y14.5-1982, para. 4.2.2 (page 36).

    Let me know if the drawing standard is ISO 1101 or one of the derivatives.
    Last edited by Kelly Bramble; 08-05-2014 at 09:14 PM.

  3. #3
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    Thanks Kelly!!!

    The date of drawing is 1988 (last revision 2012) and does not specify the standard.

    Regarding the question # 2: Do you know what "SET" mean?

  4. #4
    Administrator Kelly Bramble's Avatar
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    Quote Originally Posted by Larat View Post
    Regarding the question # 2: Do you know what "SET" mean?
    Nope.... I'm sure it is an "insider" specification...

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