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Thread: Callout for hole pattern on variable thickness

  1. #1

    Callout for hole pattern on variable thickness

    Gentlemen,

    I've got some tapped holes that need to be drilled into the side of a weldment. I'm scratching my head a little bit on calling out the holes... the picture attached can probably explain better than words.

    Hole Pattern question.jpg

    The hole depth is technically .315", but the plate thickness is .25", which really makes the holes a thru hole. However, the upper hole inside the red box is drilled transverse to the bigger plate, which means... no thru hole.

    So far I've got "8x M4x0.7 ↧.315/THRU". I guess that one hole can have its own callout, but there's got to be a better way!

  2. #2
    Administrator Kelly Bramble's Avatar
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    Quote Originally Posted by mbanerj View Post
    So far I've got "8x M4x0.7 ↧.315/THRU". I guess that one hole can have its own callout, but there's got to be a better way!
    When features are different "THRU" vs Blind, then they are seperate and different features and require separate/different callouts - most correctly.

    So, for the threaded hole features that are blind you might indicate "8x M4x0.7 ↧.315 MIN FULL THREAD" - or whatever the count is.

    For the threaded hole features that must be drilled thru to get the full thread you might indicate "8x M4x0.7 ↧.315 MIN FULL THREAD, DRILL THRU PERMISSISBLE"

    or

    For the threaded hole features that must be threaded thru the material you might indicate "8x M4x0.7 THRU"

    These would be separate callouts (specifications) clearly associated with the applicable threaded feature.

  3. #3
    Well, there's only 1 hole that falls on the side of a plate, with 7 others being thru holes only because of their location.

    Not as concise a solution as I'd like, but I guess calling them out separately is the only way to eliminate any room for interpretation.

    Thanks!

  4. #4
    Wait a second... What about

    8x M4x0.7 THRU
    (↧.315 MAX)

  5. #5
    Administrator Kelly Bramble's Avatar
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    Quote Originally Posted by mbanerj View Post
    Wait a second... What about

    8x M4x0.7 THRU
    (↧.315 MAX)
    Yes, that would work, it says to me that manufacturing is to tap all the way thru which happens to be .315 maximum depth. I would lose the depth symbol though (↧).

  6. #6
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    Quote Originally Posted by mbanerj View Post
    8x M4x0.7 THRU
    (↧.315 MAX)
    I would be reluctant to use that with the possibility of someone not reading the second part. They see "thru" and that's what they drill to. It also does not make sense, if it is a "thru" hole then how can it have a depth?

    Of course, after the drilling, when it came down to whom to blame, the driller would be wrong, but then remedial work will be needed and that is just counter productive.

    Use separate call-outs. I am not sure whey you are reluctant to do that. Does it make the drawing look untidy? Maybe, but does it remove all ambiguity? YES!

    To me you can never give too much information to the workers.

  7. #7
    Quote Originally Posted by PinkertonD View Post
    I would be reluctant to use that with the possibility of someone not reading the second part. They see "thru" and that's what they drill to. It also does not make sense, if it is a "thru" hole then how can it have a depth?

    Of course, after the drilling, when it came down to whom to blame, the driller would be wrong, but then remedial work will be needed and that is just counter productive.

    Use separate call-outs. I am not sure whey you are reluctant to do that. Does it make the drawing look untidy? Maybe, but does it remove all ambiguity? YES!

    To me you can never give too much information to the workers.
    Well, I had about two paragraphs typed out about SolidWorks, and then when it was all typed out realized that you're right. So I'm calling them out separately.

    However, the main reason I'm reluctant to call out that one hole is because I'm way more concerned with communicating design intent between engineers. In my (admittedly short) experience, much more time and money seems to be wasted on engineering when we're not all on the same page, especially on recurring low-volume builds. In this case, it seemed to me to be more effective in the long run to firmly establish the relationship between the holes to remove ambiguity for any of our engineers that modify this in the future.

    But long story short - there are now separate callouts!
    Last edited by mbanerj; 07-09-2012 at 08:00 AM.

  8. #8
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    Quote Originally Posted by mbanerj View Post
    Well, I had about two paragraphs typed out about SolidWorks, and then when it was all typed out realized that you're right. So I'm calling them out separately.
    OK, that made me chuckle. Glad to hear you are going with an individual call-out for that "different" hole. Most importantly it draws attention to the "different" aspect of that one hole.

    On your philosophy of "same page" there is never a universal solution to detailed explanations, well, not that I have experienced in 40+ year of Engineering. If anything, I tend to over explain, often stating the same thing in two different places and with different wording. To me, having things go out the door with no corrections or variations to compensate for ambiguity in instructions-to-build, is the prime consideration.

    It enhances your personal reputation, it saves your company money, it enhances your company's reputation for quality work and has it viewed favorable in a tight bid scenario. Often the lowest bidder will not get the job when someone almost as competitive - but - has a good track record of "right first time and on-time."

    As I mentioned above, (yes, repeating myself ) you can never give too much information to the workers. I've been there, seen that as I started my work life as an Apprentice Toolmaker on the shop floor.

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