Type and location of nut when attaching a bolt to steel sheet
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  1. #1
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    Default Type and location of nut when attaching a bolt to steel sheet

    Hello,

    I have a general question about where to place a bolt and what kind of bolt to use in a specific situation. I can't share all of the details of the project but will give links to some parts and a description of my issue.

    I will be attaching a ball joint with a male 1/2"-20 bolt to a 1/2" thick piece of steel. Male ball joint link:
    McMaster-Carr
    There will be some aluminum extrusion attached directly underneath the steel piece and I would like to limit the number and size of holes drilled into the extrusion. The current plan is to tap the steel sheet and have a lock-nut on top. Then screw the the ball joint into the steel sheet and tighten the nut (which would be in between the head of the ball joint and the steel). This way the aluminum extrusion can remain unmodified. The bolt of the ball joint can just be cut to the correct length. I would like to be able to adjust the height of the ball joint using the nut or by including a spacer (once a height is chosen then the bolt can be cut to length).

    Using this idea will prevent the ball joint from moving ClockWise (assuming everything is right-handed and you are looking top down)AKA tightening more. But is it true that it will not prevent CounterCW movement (loosening)? Is there a specific type of nut you would suggest? Also, is there any way you can think of attaching the ball joint without putting anything underneath the steel sheet? You could always just wield it to the top of the steel, but that kind of defeats the purpose of using bolts/nuts.

    Thanks

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    I thinks what you need is called a re-design.

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    That doesn't answer any question and is not helpful.

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    I mean, common sense tells us to use a double nut on the thing...but we have no clue, and obviously you don't either, of what you are trying to accomplish. So, either share what the "expected" end result will be or GTFO and tell your professor that your brain and internet skills are not up to the task.

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    have a lock-nut on top
    This prevents CW / CCW assuming you actually tighten it. I mean, YOU used the word LOCK

    There are also first class thread locker compounds if you don't need to "adjust" it all the time

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    No need to get nasty. I am just trying to find out if it is possible to rigidly attach the bolt coming off the joint to a tapped piece of steel by tightening a nut in between the head of the ball joint and the steel. I assume it will not work. Normally you would just attach a nut to the other side of the steel, but in my case I can't do that without drilling a big hole in the extrusion which will weaken it.

    I could obviously re-design the whole thing, but that is completely unnecessary if that I am suggesting could work.

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    Maybe I did not explain this properly. If I put a nut on the ball joint bolt, screw it into a tapped material, and then tighten the nut will it stop rotation? I expect a nut would be needed on the opposite side of the material, as you would usually attach a bolt/screw to something.

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    One picture worth 1000 words. Please post a pic or get typing because I cannot visualize your situation.

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    First you need to learn the difference between steel "sheet" and "plate"

    Next to answer you question there are several types of self locking nuts. Or you can use two nuts together to lock them to each other or use a castle nut and cotter pin, but you have to drill the stud for that.

    mcmaster locknut page:
    McMaster-Carr

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    Quote Originally Posted by EngineerNerd View Post
    Maybe I did not explain this properly. If I put a nut on the ball joint bolt, screw it into a tapped material, and then tighten the nut will it stop rotation? I expect a nut would be needed on the opposite side of the material, as you would usually attach a bolt/screw to something.

    If you tighten a bolt through that ball joint into a threaded hole it will lock the ball from rotating. No need for other lock nuts on the back.

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    Quote Originally Posted by Erich View Post
    One picture worth 1000 words. Please post a pic or get typing because I cannot visualize your situation.
    Ok, here you go:

    capture.jpg

    That nut could be a lock nut. I just threw in a random one. If you did that (then just cut the extra bolt off), would it loosen if you rotated it CCW?

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    Quote Originally Posted by EngineerNerd View Post
    Ok, here you go:

    capture.jpg

    That nut could be a lock nut. I just threw in a random one. If you did that (then just cut the extra bolt off), would it loosen if you rotated it CCW?
    No need for a lock nut in your situation, I would use a flange nut. As long as the shaft through the ball does not hit the body it will not rotate. If the shaft does hit the body then it will either rotate, bend or break, depending on how hard the hit is, but under normal use with no interference you will be fine.

    Can you turn the ball joint 90º and have the stud end parallel with the plate and a bolt going through the ball into the threaded hole? Spacers as needed to get proper height.

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    I did not have trouble visualizing what you were describing. Yes the nut will lock the ball joint. Of course it depends on what exactly you are doing. I can think of all sorts of ways for that to work loose, or not, depending.


    Sent from my iPhone using Tapatalk

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    Quote Originally Posted by Rob F. View Post
    No need for a lock nut in your situation, I would use a flange nut. As long as the shaft through the ball does not hit the body it will not rotate. If the shaft does hit the body then it will either rotate, bend or break, depending on how hard the hit is, but under normal use with no interference you will be fine.

    Can you turn the ball joint 90º and have the stud end parallel with the plate and a bolt going through the ball into the threaded hole? Spacers as needed to get proper height.
    Ok. Thanks Rob F. Unfortunately I can't do that, but that is an interesting idea so thank you.

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    Not sure why; never seen lock nuts flanged or with washers. I see them a lot on threaded plates, sometimes Loctite on main threaded area (bolt or load nut)but never on lock nut. I do not know why no washers and only one section with Loctite or vibratite, just seeing a lot in similar situations. Locking collars are opposite, which collar gets clamped to threads. Again, no reason I can see other than 'way it is done'.

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    OK, you are asking a bunch of machinists an ENGINEERING question. And your question does not include enough information for a definite answer to be formulated.

    A lock nut functions by placing the segment of the screw thread in the primary threads (nut or other threaded part and the lock nut itself). This tension produces friction between the male and female threads and between the nut and the part with the primary threads (your 1/4" steel plate). It is this friction AND THE AMOUNT OF FORCE THAT IS APPLIED that determines weather the various parts will move in relationship to each other or if they will remain fixed. And the amplitude of this friction will be determined by other factors as well, including the types of surfaces, the presence or absence of any lubrication between them, and on the amount of torque that is used when tightening that lock nut. NONE of these factors are included in your question. So it is not possible to state weather this will be a successful design or not.

    One thing that I can assure you is that the side of the screw thread that the lock nut is on does not make a lot of difference. And that difference will probably be dependent on the direction in which a torque (rotational load) is applied to the screw. In one direction that torque will help loosen the lock nut and in the other direction it will tend to tighten it. These two effects will switch direction depending on which side of the main threads the lock nut is placed on. But it need not be a major factor.

    And, as others have said, thread locking compound will help in this respect.

    What it seems like you are doing is known as "seat of the pants" engineering. Another way of expressing that is taking a WAG at it. WAG = Wild Ass Guess. Many things are made this way, but the results are never completely known until there is a good amount of experience with the product in actual use. This is why engineers study for years in college and use things like formulae.

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    1) yes.

    2) It's a jam nut.

    3} Large torque can loosen it.

    4) The assembly will be taller than it needs to be.

    3) If the tapped hole is shallow in the aluminum you risk stripping
    the threads getting it tight enough to resist torque on the heim joint.

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    It can work but you need to do a little more planning.

    The shank length should be correct for the mounting height before installation, not cut off afterwards. If you can't buy the correct ones you need to learn how to cut and dress the end of a threaded part.

    Minimum threads engaged must be at least 4 so you have plenty of depth in a 1/2" steel plate threaded 1/2-20.

    If you are sure there will be no significant rotational force on the housing (which would be a result of improper design) it will work.

    • Use liquid thread locker at assembly.
    • Pre-install your "jam nut" (use a heavy nut, not a thin jam nut.
    • Install the rod end to finish height.
    • While holding the body, torque the jam nut.
    • Allow time for thread locker cure before putting to use.


    While IMO that is far from an ideal design it should work as long as there is no serious twisting action on the BODY of the rod end. If there is the design is fatally flawed.

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    just a thought about the whole joint design - it is difficult to tell from the description how the forces are applied to this joint (see the attached image), if they are in the green arrow direction, you're fine, but if they are also in red direction, the locking nut (and basically any nut will work in this application, but generally these nuts are 1/2-3/4 thickness of a normal nut, since they are there to provide locking function and take as little space as possible) may become loose when the bolt bends under load and the nut is compressing material under it, few iterations of this back and forth motion may loosen the nut, big flange under the nut might help, or a large washer
    edit: forgot to add picture
    capture.jpg

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    Quote Originally Posted by EngineerNerd View Post
    That doesn't answer any question and is not helpful.
    Quote Originally Posted by EngineerNerd View Post
    No need to get nasty. I am just trying to find out if it is possible to rigidly attach the bolt coming off the joint to a tapped piece of steel by tightening a nut in between the head of the ball joint and the steel. I assume it will not work. Normally you would just attach a nut to the other side of the steel, but in my case I can't do that without drilling a big hole in the extrusion which will weaken it.

    I could obviously re-design the whole thing, but that is completely unnecessary if that I am suggesting could work.
    I don't understand who here would offer valuable design time to try to help some one that post's a very vague thread, and then exhibits this attitude toward said help.


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