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  1. #1
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    slotted holes and bolts question

    forgive me for asking what might be a stupid question to you all but ive never dealt with slotted holes this way before and its quite important. this is just a rough template but say i make a plate that needs to have adjustment and i tighten the bolt like in the pic below, how do i prevent the bolt from slipping due to vibration over time?

    Thanks

    Attached Thumbnails Attached Thumbnails bolt.jpg  

  2. #2
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    Re: slotted holes and bolts question

    A flat washer and a lockwasher.


  3. #3
    Community Moderator Jim Dawson's Avatar
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    Re: slotted holes and bolts question

    Once adjusted into to position and tightened, you could pin the plate to the frame. This is common in machine tool building to prevent lateral movement in assemblies.
    Jim Dawson
    Sandy, Oregon, USA

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    Re: slotted holes and bolts question

    Quote Originally Posted by Jim Dawson View Post
    Once adjusted into to position and tightened, you could pin the plate to the frame. This is common in machine tool building to prevent lateral movement in assemblies.
    thanks this would help

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    Re: slotted holes and bolts question

    How about the ballscrew, it is important that the ballscrew doesnt spin and i feel as if a nut at the end aint enough. i was thinking of making a plate that slots over the thread pretty much like a large washer and then tighten the nut once in position and then bolt the plate to the main mounting plate with the 4 holes to stop the ballscrew from moving left or right in the slotted hole over time. would this work?

    Attached Thumbnails Attached Thumbnails Untitled2.jpg  

  6. #6
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    Re: slotted holes and bolts question

    The ballscrew is designed to turn... that is how the machine moves. There should be bearings on both ends of the ballscrew.

    https://www.phidgets.com/?tier=3&cat...=32&prodid=682
    Gecko G540, Rack and Pinion Drives-X and A axis, 1/2-10 5 Start Acme-Z Axis
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  7. #7

    Re: slotted holes and bolts question

    If you want to prevent rotation, you can put a nut on both sides and clamp your mounting bracket between them, only use one to apply tension. As for preventing loosening under vibration in your first image, double-nut or a belleville washer would be better choices than the so called spring-lock washer shown above.

    When working with vibrations in electrical cabinets or on vehicles, spring-lock washers are wholly discounted, they don't hold over time. A double-nut would be a thin nut first and a standard nut tightened down onto it, locking them together. You want to tighten the final nut until you start to feel that 'yield' sensation, that is when the threads in one or both sides begin to deform and it won't vibrate loose. You can also use a distorted thread lock nut. These are the kind that are all metal, no nylon thread lock features. They are usually a slightly ovoid shape. Only use them one time, if you remove the nut, use a fresh one in any locknut situation.

    Belleville washer: https://www.mcmaster.com/belleville-...isc-springs-7/
    Thin nut: https://www.mcmaster.com/thin-nuts/h...-nuts-grade-8/
    Distorted Thread Locking Nut: https://www.mcmaster.com/locknuts/hi...read-locknuts/

    EDIT: Just as a note, you want to tighten until the belleville just goes flat. The belleville provides the proper holding tension at that point. If you need a high range of compression for some reason, then you can stack bellevilles back to back. You can also use flat washers or either side of the belleville or both, if you feel your bolt head or nut don't make good contact with the belleville.
    Attached Thumbnails Attached Thumbnails Belleville_Flange.jpg  

  8. #8
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    Quote Originally Posted by adam_m View Post
    The ballscrew is designed to turn... that is how the machine moves. There should be bearings on both ends of the ballscrew.

    https://www.phidgets.com/?tier=3&cat...=32&prodid=682
    Not when using a rotating ballnut or moving ballnut some may call it

  9. #9
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    Re: slotted holes and bolts question

    Quote Originally Posted by reefy86 View Post
    Not when using a rotating ballnut or moving ballnut some may call it
    Indeed.
    Gecko G540, Rack and Pinion Drives-X and A axis, 1/2-10 5 Start Acme-Z Axis
    4-THK HSR 25 Linear Slides, KL23H2100-35-4B, Power Supply-KL-600-48 48V

  10. #10
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    Quote Originally Posted by StrawberryBoi View Post
    If you want to prevent rotation, you can put a nut on both sides and clamp your mounting bracket between them, only use one to apply tension. As for preventing loosening under vibration in your first image, double-nut or a belleville washer would be better choices than the so called spring-lock washer shown above.

    When working with vibrations in electrical cabinets or on vehicles, spring-lock washers are wholly discounted, they don't hold over time. A double-nut would be a thin nut first and a standard nut tightened down onto it, locking them together. You want to tighten the final nut until you start to feel that 'yield' sensation, that is when the threads in one or both sides begin to deform and it won't vibrate loose. You can also use a distorted thread lock nut. These are the kind that are all metal, no nylon thread lock features. They are usually a slightly ovoid shape. Only use them one time, if you remove the nut, use a fresh one in any locknut situation.

    Belleville washer: https://www.mcmaster.com/belleville-...isc-springs-7/
    Thin nut: https://www.mcmaster.com/thin-nuts/h...-nuts-grade-8/
    Distorted Thread Locking Nut: https://www.mcmaster.com/locknuts/hi...read-locknuts/

    EDIT: Just as a note, you want to tighten until the belleville just goes flat. The belleville provides the proper holding tension at that point. If you need a high range of compression for some reason, then you can stack bellevilles back to back. You can also use flat washers or either side of the belleville or both, if you feel your bolt head or nut don't make good contact with the belleville.
    Thank you for the reply do you have a cad model to demonstrate this? If it wasn't for the rotating ballnut it would be simple by just having 2 fixes bk supports. Or does anyone have a picture of one they have done in the past? Not many rotating ballnut users out there unfortunately

  11. #11
    Community Moderator Jim Dawson's Avatar
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    Re: slotted holes and bolts question

    I would use a threaded, clamp type shaft collar, and bolt that to the mounting plate.

    https://www.mcmaster.com/bolts/shaft...shaft-collars/
    Jim Dawson
    Sandy, Oregon, USA

  12. #12
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    Quote Originally Posted by Jim Dawson View Post
    I would use a threaded, clamp type shaft collar, and bolt that to the mounting plate.

    https://www.mcmaster.com/bolts/shaft...shaft-collars/
    Interesting, would something like this work so it screws onto the ballscrew and then tightened and then bolted to the mounting plate or would this be significantly weaker then a nut?

    Thanks

    Attached Thumbnails Attached Thumbnails Screenshot_20210927-202938_Chrome.jpg   Screenshot_20210927-202938_Chrome.jpg  

  13. #13
    Community Moderator Jim Dawson's Avatar
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    Re: slotted holes and bolts question

    I guess that would work OK. You would just screw that onto the ball screw, then use a jamb nut to secure.

    The alternative would be to thread the plate and just use a jamb nut to secure. The advantage of using some kind of nut that would bolt to the plate is that you could assemble it loose then do an adjustment for final alignment before tightening in place.
    Jim Dawson
    Sandy, Oregon, USA

  14. #14
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    Re: slotted holes and bolts question

    Think i am going to go with this method i have done, ballscrew machined flat to prevent it from turning once plates are attached and then bolted through the ballscrew its self and then once adjusted in place then bolt all plates together. you think this will work well?

    Attached Thumbnails Attached Thumbnails 5.jpg   6.jpg   7.jpg   8.jpg  


  15. #15
    Community Moderator Jim Dawson's Avatar
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    Re: slotted holes and bolts question

    As long as the ''D'' is a tight enough fit on the ball screw, I don't see a problem.
    Jim Dawson
    Sandy, Oregon, USA

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    Quote Originally Posted by Jim Dawson View Post
    As long as the ''D'' is a tight enough fit on the ball screw, I don't see a problem.
    Thanks that's good to hear

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    Just one last question how do I know how much to tighten/preloaded the ballscrew?

    Sorry for the questions

  18. #18
    Community Moderator Jim Dawson's Avatar
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    Re: slotted holes and bolts question

    Quote Originally Posted by reefy86 View Post
    Just one last question how do I know how much to tighten/preloaded the ballscrew?

    Sorry for the questions
    I normally preload them to where I can feel a small amount of resistance when turning by hand. I don't know how to describe it, but maybe a little bit snug? There is most likely some specification published somewhere, but I have always done it by feel.. Maybe not the best way, but it works for me.

    Short story: I was working on a machine with a German tech, there was a callout for ''normal tightness'' I asked the German tech what that was, he said '' Every good German tech knows what that is.'' Kind of the same as above.
    Jim Dawson
    Sandy, Oregon, USA

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