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Thread: Coil Rod/Bolt/Nut Specifications

  1. #1
    Associate Engineer
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    Coil Rod/Bolt/Nut Specifications

    Hello,

    I need to model a number of rods and fasteners using coil threads. Where can I find the specifications for these?

    I did a search and could not find anything relevant.

    Yes, I'm a newbie...

    Thanks.

  2. #2
    Administrator Kelly Bramble's Avatar
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    Do you have a specification? Industry standard ?
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

  3. #3
    Principle Engineer
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    Find a copy of a book titled: "Machinery's Handbook" published by Industrial Press. The engineer guiding your modeling efforts should have specified the thread and should be able to help you find a copy of the book.

    If there is no engineer on the project google "Kansas City skywalk" to see what can go wrong with threaded rods.

  4. #4
    Associate Engineer
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    One of the threads is for a 3/4-4.5 bolt and nut. Thanks for the tip on the book. I was unaware it covered coil threads.

    I am aware of the sidewalk failure. Very sad. Many failures by many hands...

    Anyway, this is for concrete formwork.

    Thank you for the help!

  5. #5
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    I have a copy of the 22nd edition of the handbook, and I was unable to locate the coil thread profile data. Can someone verify that the recent edition contains this information?

  6. #6
    Principle Engineer
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    Look for 'Unified Screw Threads".

  7. #7
    Technical Fellow jboggs's Avatar
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    I'm not aware of any standard for so-called coil threads. When you say "coil threads", do you mean as in Helicoil type thread inserts? You can find their information on their website.

  8. #8
    Associate Engineer
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    These are not HeliCoil inserts. There is nothing in the handbook specifying this thread profile under the UNC thread section, at least in the edition I have. Some examples:



    Thanks.
    Attached Images Attached Images

  9. #9
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    Coil Rod/Bolt/Nut Specifications

    @ sjmccart
    I am rowing the same boat, Have you succeed to get the standard ?

  10. #10
    Technical Fellow jboggs's Avatar
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    I have been in machine design for over four decades. I will admit there are a lot of things out there I am unfamiliar with, but I have never even heard of a so-called "coil thread". I am, however, very familiar with heli-coil threads and use them a lot. But you say this isn't for coiled thread inserts.

    Also, I have never seen a screw thread that looks like the one in the image above. It seems kind of pointless because it couldn't create much retaining force. It does look a little like a typical thread on a ballscrew, for linear motion applications. But I've never seen that thread form used in fastener applications.

    My first thought is that this might be similar to the thread one sees on light bulb bases, kind of "rounded off" thread form.

    All of which brings me to the question no one has asked yet. What is the application? Where is this thread used? The answer to that question might help to locate the information you need.

  11. #11
    Principle Engineer Cragyon's Avatar
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    Looks like a ball screw thread.

    See bottom of this webpage: https://www.engineersedge.com/mechan...ions_15235.htm

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