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Thread: Spindle drive bearings

  1. #1
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    Default Spindle drive bearings

    Howdy all,

    I'm going trough the belt drive conversion and I have few questions...

    Would you consider using tapered roller bearings for spindle drive sleeve? I've got my setup almost completed and then I realised that the tapered rollers that I've acquired would probably need frequent lubrication as there are no provisions to keep the grease trapped within the bearings...

    Would this type of bearing be NO-NO for this location? What are your thoughts on this bearing position?

    My goal is to reach 6000 rpm with the machine. The tapered rollers are rated to 8000 rpm. I have not found any AC bearings in adequate size for the mentioned position, but I could grab some 6008 2ZR deep groove bearings if your convince me that tapered rollers are not a good idea.

    Hey, feel free to tell me what would you do if you were converting the machine.

    Cheers
    Zeljko

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    Member handlewanker's Avatar
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    Default Re: Spindle drive bearings

    Hi, without seeing the design it's difficult advising how to improve the sealing at the bottom bearing set.

    I would have gone for angular contacts in the conventional spindle configuration with separate seals as is normal......why re-invent the wheel..

    Normally you would have a seal in the bearing cap, or a labyrinth seal that is attached to the bottom of the spindle to, keep the bearings and lube in.

    Post a sketch of the spindle bearing layout for further evaluation and advice.

    BTW....why the heck are you using tapered rollers when the conventional way is to use angular contacts?.......tapered rollers are not all that good for high speed anyway.
    Ian.



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    Default Re: Spindle drive bearings

    Howdy Ian,
    I am going with AC bearings for the spindle. The bearings I'm on about are the spindle drive collar bearings. The collar used to be supported with 2 6008 deep grove ball bearings. These two bearings are actually holding the tension of the belt drive system. I should have left the original ones in util they smoke out, but I just removed all the bearings out while I was cleaning the cover.

    I'll grab some photos tomorrow if the weather permits.





    Quote Originally Posted by handlewanker View Post
    Hi, without seeing the design it's difficult advising how to improve the sealing at the bottom bearing set.

    I would have gone for angular contacts in the conventional spindle configuration with separate seals as is normal......why re-invent the wheel..

    Normally you would have a seal in the bearing cap, or a labyrinth seal that is attached to the bottom of the spindle to, keep the bearings and lube in.

    Post a sketch of the spindle bearing layout for further evaluation and advice.

    BTW....why the heck are you using tapered rollers when the conventional way is to use angular contacts?.......tapered rollers are not all that good for high speed anyway.
    Ian.




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    Member ninefinger's Avatar
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    Default Re: Spindle drive bearings

    Definitely use standard deep groove bearings for this application, the load is entirely radial so no need or benefit to using angular or tapered rolling bearings, those are primarily for handling both axial and radial loads.
    Mike



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    Default Re: Spindle drive bearings

    Thanks for sharing your thoughts with me Mike,
    I've grabbed a pair of inexpensive 6008 2RSR C3 bearings. Their limit speed is rated at 6700 rpm which is probably not achievable with my pulley setup (1:2 and 2:1 with a 4 pole motor)

    I hope I'll have some progress photos soon.



    Quote Originally Posted by ninefinger View Post
    Definitely use standard deep groove bearings for this application, the load is entirely radial so no need or benefit to using angular or tapered rolling bearings, those are primarily for handling both axial and radial loads.
    Mike




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    Default Re: Spindle drive bearings

    The speed limit is likely due to the seals - they can generate a lot of heat. Shielded bearings (6008ZZ) will have a much higher speed rating (~11000 rpm with grease lube) and should be suitable for the application - unlikely to see much or any debris or liquids up there.
    But I wouldn't worry about it too much, if overspeeded (heated) the seals will start to let go and as long as the grease stays in they will turn themselves into rubber shielded bearings!



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    Default Re: Spindle drive bearings

    It has been a bit since I have posted here but I agree with Ninefinger.

    I have had standard deep groove bearings on the upper side of the spindle for years and have only repacked them once. I constantly run RPMs of ~4000 and up to 6500.



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    Default Re: Spindle drive bearings

    Thanks for your help guys.
    The TRs are out and the deep grove BBs are in.

    I am running the spindle today and having fun with the configuration of the open loop vector drive. it is really nice to see the motor run at such low rpm and still have plenty of torque!



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