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Thread: Drawing ambiguity

  1. #1
    Associate Engineer
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    Drawing ambiguity

    Dear members,


    Problem is supplier has drilled the 4mm holes from opposite face.
    But we are contemplating it's a drawing error where details mentioned are not enough.
    can someone point out the errors in this drawing?
    Untitled.jpg




    Thanks.

  2. #2
    Administrator Kelly Bramble's Avatar
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    Third or first angle drawing?

    If drawing is declared as first angle projection - 4mm holes specification is correct.
    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
    Third or first angle drawing?

    If drawing is declared as first angle projection - 4mm holes specification is correct.
    Hi Kelly we make drawings to Third angle projection.

    In this case could you tell me what is wrong with the drawing in more detail?

    Apologies not very well versed in this subject.

    Regards,
    Mustafa

  4. #4
    Administrator Kelly Bramble's Avatar
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    Given vague - limited information..

    The line showing the center bolt circle should be a center line.

    On the 4 mm holes, what does "Full Dia" do? What else would the hole features be?

    There seems to be an extra surface line in the left plan view.

    "PCD" is a new on me even after publishing 6 books on dimensioning and tolerancing as well as consulting/training within 100's of organizations all around the world..

    If the engineering drawing is produced in the USA, parallel dimensions and Fractions are so... 1960's and before.

    Based on the arrangement of the dimensions it is very unlikely there is any thought given to the functional requirements of the end item.

    Technically, there is enough information to get the 4mm holes on the mount/flange side (assuming that's what going on).
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  5. #5
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    Thanks Kelly,
    Agree with you, perhaps the drawing could be made more clear. As the cutting plane is not passing through the 4mm hole, it is not detailed in a cross section view. An additional section of side view could be created to mention the position of the 4mm hole.

  6. #6
    Administrator Kelly Bramble's Avatar
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    Quote Originally Posted by mkpash View Post
    Thanks Kelly,
    Agree with you, perhaps the drawing could be made more clear. As the cutting plane is not passing through the 4mm hole, it is not detailed in a cross section view. An additional section of side view could be created to mention the position of the 4mm hole.
    All drafting practices including modern ASME and ISO specify that a blind hole starts from the surface which it is shown as non-hidden or by solid outlines.

    Engineering drawings should be created with the intent of being as clear as possible to those who must interpret it.
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  7. #7
    Technical Fellow jboggs's Avatar
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    The drawing could use much improvement. Most of the lines looked like object lines to me. None of them looked like hidden lines or tangent lines. Based on the arrangement of the lines in the left view I would assume the drawing is in third angle projection because the edges shown in that view seem to align with features shown in the section. But some of those lines are tangent lines and should be drawn as such. They are drawn as object lines and are therefore confusing.

    Do your drawings state that they are drawn in third angle projection? Or is it just an assumption?

    Regardless of which type of projection you normally use, the section cutting line A-A includes arrows specifying the view orientation.

    One way to eliminate confusion would be to include this statement in your hole description: "DRILL FROM FAR SIDE" or "DRILL FROM NEAR SIDE".

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