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Question SFX 250mm High quality ballscrew and nut upgrade. Plus upgrade stronger FK12 bearing?

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Trigen, Oct 31, 2025 at 04:12.

  1. Trigen

    Trigen Active Member

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino
    Hi guys!

    Ive had my sfx 100 (250mm ) 3 actuator setup. 2x front 1x back for some time now. However i have one actuator that i simply cant get right. Ive checked everything is square but when i tighten it up it starts to bind and i've destroyed a couple of FK12 bearings. Ive tried every different combination. widened the holes and so on. I replaced the ballscrew but same issues. Even reprintet it all. So perhaps somehow the threaded inserts are off but seems so weird since i've widen the holes on the 3d printed part. Ive only gotten it slightly better. I may need to insert some threaded rods to bypass the threaded inserts just to see but im abroad for another two months.

    In any case im thinking i want to upgrade to high grade ones that i know is 100% true/straight as i hate the wobble feel. And i would like to have the FK12 with stronger/more bearings to handle more load.

    Any of you have some links that could help me out?

    I live in Norway
    Last edited: Oct 31, 2025 at 05:54
    Trigen, Oct 31, 2025 at 04:12
    #1
  2. Aerosmith

    Aerosmith Active Member

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    3DOF, AC motor
    Some pictures might help to diagnose what's wrong. To check the spindle the easiest way is to put a bearing on one end and spin it with a power drill on the other. You see it wobble when something is out of round.
    • Like Like x 1
    Aerosmith, Oct 31, 2025 at 09:52
    #2
  3. Trigen

    Trigen Active Member

    Joined:
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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino
    Unfortunately im abroad until 18 december so i cant show any pics right now. I thought i'd order so i have it when i come home. Ive already the ballscrew once so i dont think its whats causing the binding. Wobble sure but not the binding. Cant be 100% sure but the other two has no issues. Only this 100x100 profile so im leaning towards an issue with it. Its really weird to be honest. Everything looks godo but still binds

    On a side note ill order some C3 quality FK12 as i only have C7 and i didnt know any better. https://www.damencnc.com/en/fk12-fixed-ballscrew-support-units-c3-quality/a1432

    "There are many FK blocks on the market, and the problem is, they all look the same, but prices differ greatly. We have chosen to offer only the highest quality bearings (P5 Taiwan), which are suitable for ballscrews in quality classes C3 to C10. Be aware that many webshops offer only the C7 type, which has normal deep groove bearings, and then don't have any pre-load, meaning you will have play in the axial direction."
    Last edited: Nov 1, 2025 at 03:33
    Trigen, Nov 1, 2025 at 03:26
    #3