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Thread: Older engineering drawing symbols

  1. #1
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    Bang Head Older engineering drawing symbols

    Can anyone help me identify the highlighted symbol? Have had no luck trying to interpret its meaning. Please... enlighten me with your wisdom.
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  2. #2
    Administrator Kelly Bramble's Avatar
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    An underlined dimension means that it is not to scale...
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

  3. #3
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    Quote Originally Posted by Kelly Bramble View Post
    An underlined dimension means that it is not to scale...
    Thank you! Is this tribal knowledge or is it noted in a particular spec? I couldn't find any references.

  4. #4
    Administrator Kelly Bramble's Avatar
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    Most recent Y14.5-2009 and every other dimensioning and tolerancing standard since about ... 1947.
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

  5. #5
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    I think 127cfc was particularly wondering WHY there would be an underlined, i.e., out-of-scale dimension on a drawing.
    The answer is, back in the days of paper, pencil & drafting boards (where I cut my teeth), if a dimension changed only slightly, you did NOT go to the effort of redrafting (manually!) the whole view. You erased the wrong dimension & put in the corrected one, underlined to show that it is out-of-scale. And that concludes this tour of Engineering History...

  6. #6
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    Well written Jeff.

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