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Question Suggestions for 3DOF?

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Opast, Jul 8, 2025 at 09:45.

  1. Opast

    Opast New Member

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    I'm planning to build a 3DOF front motor design, similar to the picture but with my own touch. I will probably be upgrading the lower and middle frame to 2 inch by 8 inch lumber to make it stiffer due to the wheelchair motor mount, and everything else 1 inch 16 gauge steel square tubing. The wheelchair motors I have are 18:1 gear ratio, 24V, but I'm planning to run them at around 26V. The question is, how wide should I make the upper frame connected to the seat since my wheelchair motors have an 18:1 gear ratio? The original designer used a 16 inch width due to the limited steel tubes but I have plenty at the moment. Would you recommend going bigger, smaller, or keeping it the same? After using the calculator here, it kind of got me more confused unless I was doing something wrong. The plan is to use the sim rig 65% flight sim BMS, VtolVR and 35% racing. Would you suggest making similar angle rods or differently?

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    Last edited: Jul 8, 2025 at 10:00
    Opast, Jul 8, 2025 at 09:45
    #1
  2. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    Innovative tech specialist for NGOs
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    My Motion Simulator:
    3DOF, DC motor, JRK
    Not a criticism of DMax, just a design related observation, independent of materials used or dimensions, a lever is most effective at 90 degrees and the greater the distance from the pivot under the seat to where the rods connect the greater the inherent design leverage, and the less strain on the motors.

    In other words, if the motors are mounted near your feet having the rods connect near your feet, rather than knees, has greater inherent design leverage.
    noorbeast, Jul 8, 2025 at 13:56
    #2
  3. Attyla.pl

    Attyla.pl Active Member

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    My Motion Simulator:
    2DOF, DC motor, Arduino
    A bit this DMax design does not fit for flying in BMS
    see this design
    https://www.xsimulator.net/community/threads/diy-3-dof-inspired-by-dof-reality-h3-model.18273/
    much more compact
    I had two similar for flying (wooden and metal ) and this layout for flying with motors at the back was great.
    The 18:1 ratio doesn't tell you much, how much RPM ( revolutions per minute ) do your motors have ?
    What maximum current do they draw in Amperes

    Will you be using a third motor for the TL ?
    Attyla.pl, Jul 8, 2025 at 15:01
    #3
  4. Opast

    Opast New Member

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    I have 3 identical motors, the same motors that DMax used in previous build wheelchair motors. I posted a picture of the motors in the first post. I didn't get a chance to measure rpm yet but from a quick glance they are 18:1 Why do you think motors in the back design is better for flying? The design looks great but I don't think my motors will have enough torque for the design.
    Opast, Jul 8, 2025 at 17:52
    #4