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3dof seat mover - limit rod motion

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by nanocba83, Feb 1, 2026 at 04:30.

  1. nanocba83

    nanocba83 New Member

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    I'm trying to build a 3dof seat mover with four scooter motors and crank & rod mechanism. However I'm finding stuck at finding a way to restrict the motion of the rod so they only move in one direction. My idea is to try to find some sort of rail with bearings so the movement is smooth but I can't for the life of me find anything close to it.

    I know that four motors is over constraining the system but I wanted to test the additional power provided by an extra motor. So right now I feel I'm stuck at figuring out the last bits of the mechanical aspect.

    I'm attaching a photo of my build so far for reference.

    Attached Files:

    nanocba83, Feb 1, 2026 at 04:30
    #1
  2. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    noorbeast, Feb 1, 2026 at 07:54
    #2
  3. Radioproffi

    Radioproffi Active Member Gold Contributor

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    This can create a significant amount of parasitic movement, which will place greater strain on some motors.

    An alternative would be a gas strut from a computer chair in the center with a joint attached to the top and a single Watt mechanism to prevent lateral movement.
    Radioproffi, Feb 1, 2026 at 11:11
    #3
  4. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    Indeed that is totally possible and I built my own adjustable version over a decade ago, without the need for a Watt mechanism: https://www.xsimulator.net/community/threads/dx-compact-simulator.5866/
    noorbeast, Feb 1, 2026 at 11:19
    #4
  5. accelero

    accelero Member

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    Hi,
    what if you use another mechanism , like the D.mover implementation, but using motors instead of linear actuators ?
    accelero, Feb 1, 2026 at 11:22
    #5
  6. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    As in a rotary lever that moves a vertical push-rod acting on the ground?

    It could be made to work but operates through an arc, in those circumstances a linear actuator likely makes more sense.

    Sketch out what you have in mind, or make a working model, as that would likely tease out the pros and cons: https://www.xsimulator.net/community/faq/build-a-model-to-test-your-design-ideas.136/
    noorbeast, Feb 1, 2026 at 11:29
    #6
  7. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    noorbeast, Feb 1, 2026 at 11:34
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  8. Radioproffi

    Radioproffi Active Member Gold Contributor

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    Radioproffi, Feb 1, 2026 at 11:37
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  9. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    Yes, one of the many design variations that are possible/viable.
    noorbeast, Feb 1, 2026 at 11:40
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  10. Gadget999

    Gadget999 Well-Known Member

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    if you change the angle of the rods the platform will become stable

    consider a different layout of the motors

    raise the motors so that they will not hit the ground
    Gadget999, Feb 1, 2026 at 18:24
    #10
  11. nanocba83

    nanocba83 New Member

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    As I'm going through the mentioned posts wanted to say to you all I'm really thankful. All the things you have shared are truly inspiring and guiding me to the right path.

    I'm definitely re-thinking this considering the input provided.

    Even with four motors, or you think I should move to three to simplify it?
    Thanks for posting this. I'm getting some ideas from this thread.
    This one thread is a jewel as well! Lots of ideas and great work there!
    nanocba83, Feb 1, 2026 at 19:45
    #11
  12. Gadget999

    Gadget999 Well-Known Member

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    You may as well use 4 motors as you have them
    Gadget999, Feb 1, 2026 at 23:42
    #12
  13. nanocba83

    nanocba83 New Member

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    I'm back at the drawing board and I feel I'm settling down to three motor layout and save the fourth one for traction loss on platform which is more standard configuration. However I do also want to try some new things out and was wondering about having this lineal bearing fixed (one per rod) to restrict linear motion.
    What do you think?

    Attached Files:

    nanocba83, Feb 2, 2026 at 07:32
    #13
  14. Gadget999

    Gadget999 Well-Known Member

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    Can you do a basic sketch of what you are planning - i am not really sure what you are proposing
    • Agree Agree x 1
    Gadget999, Feb 2, 2026 at 09:10
    #14
  15. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    I am not sure in what manner you envisage implementing this particular bearing design, could you please sketch out, explain and post what you have in mind.
    noorbeast, Feb 2, 2026 at 09:11
    #15
  16. nanocba83

    nanocba83 New Member

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    I'm sorry should have provided a drawing too. Here it goes. Only modeled two because that's basically what it would take to restrict both lateral and longitudinal movement, but may as well be extended to all of them.

    Attached Files:

    nanocba83, Feb 2, 2026 at 15:38
    #16
  17. Gadget999

    Gadget999 Well-Known Member

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    My Motion Simulator:
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    if you look at most 3dof sims the actuator are hinged and can only move in a single plane

    there are 3 of them that are arranged to stop the rig from wobbling or toppling

    you may be able to get the rig to be stable if you position 4 rods that are angled like on a 6DOF sim

    you may need to experiment with the angles - I suggest you build a small model and see if you can make it stable - see attached pic

    the linear bearings you are suggesting may work - so may a pair of panhard rods

    Attached Files:

    Gadget999, Feb 2, 2026 at 18:41
    #17