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Showroom Aluminium 3DOF (with Heave) Build Log

Discussion in 'DIY Motion Simulator Projects' started by Tim McGuire, Oct 24, 2017.

  1. Brett Horton

    Brett Horton Active Member Gold Contributor

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    What are the specs on your helper spring? Any links by chance?
    I am wanting to upgrade my rig to a true heave unit and also continue to use my 25:1 like yours.
    I have been told for obvious reasons that they will not hold the load (And agree). Your solution is easy and seemingly a great solution to my needs.
    I to will be adding traction loss to my setup from the start (Already incorporate it into my current rig)
    Do you think it is possible to still utilize the 25:1 motors and include the additional weight of pedals and wheel (And associated gear)? I am wanting to incorporate a full motion rig in this next build (currently use a seat mover only with traction loss) What is your Z axis range?
    Sorry for the random questions lol
    Thanks for the inspiration!
    Last edited: Nov 6, 2017
  2. Tim McGuire

    Tim McGuire "Forever a work in progress"

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    There are no links to the design files (it's all pretty much custom), but I can probably upload my drawings at some point.

    I'm using 4 these springs:
    https://www.leespring.com//product_spec.asp?springType=C&partnum=LHL750A15

    and the bearings are just your standard aliexpress 20mm linear ones.
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  3. Brett Horton

    Brett Horton Active Member Gold Contributor

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    Rgr thanks,
    I do not necessarily need the design files, was just interested in the springs you purchased.
    Thanks for the info
    Don't go to any trouble for me on drafting your design.
    If you don't mind I will just ask a few questions here and there.
  4. tahustvedt

    tahustvedt Member

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    Yeah, I know that's what everyone is doing with under-the-seat hinges, but the tilt won't be sensed felt until the rig stops moving. The push happens immediately.
  5. Tim McGuire

    Tim McGuire "Forever a work in progress"

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    Ask away! Theoretically you could add a wheel and pedals, you'd just need to make sure the mounts are very far from the pivot, and the rig is well balanced, and use short CTC levers.

    True, and this is something I grappled with as well, but I don't notice the short delay as much as the change in motion when the rig completes the movement. The ideal solution would be something like combining forward translation and tilting backwards like in a 6DOF, but for a small rig like this having the response "backwards" is the standard mode of operation for most people. You notice the change in direction far more than the push.
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  6. Archie

    Archie Eternal tinkerer

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    That heave mechanism is awesome.
    It's one of those hard to achieve forces on a sim that is not a 6 DOF and you have nailed it.

    You could manufacture that mechanism and a small queue would form!

    Great sim. Well done. :thumbs
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  7. Tim McGuire

    Tim McGuire "Forever a work in progress"

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    Thanks for the praise! I'm not sure about manufacturing, but I could definitely put up my solidworks drawings for anyone who wants them.
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  8. Brett Horton

    Brett Horton Active Member Gold Contributor

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    Please do, I would like to see them
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  9. Tim McGuire

    Tim McGuire "Forever a work in progress"

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    Here you are :)
    Some of the bits on my actual rig have been modified for easier manufacturability, etc. Also, the design for this could have been made MUCH simpler, but I have access to a CNC milling machine so I decided to get fancy. You could probably make some changes and be able to fabricate it with just a drill press and some alignment pins.

    Here's a link to the solidworks files:
    https://www.dropbox.com/sh/4n4ezdebdojlm3i/AAD7DChrYvcGANDG5PEZrDx_a?dl=0

    Attached Files:

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  10. Brett Horton

    Brett Horton Active Member Gold Contributor

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    My Motion Simulator:
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    Thanks for the link, but it says I can't download due to number of prior downloads...
  11. Zed

    Zed VR Simming w/Vive

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    @Tim McGuire - when you had the gearboxes apart to put in the solid shafts, did you happen to look at the backlash or if the worm gear had endplay?
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  12. Tim McGuire

    Tim McGuire "Forever a work in progress"

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    Not again... I'll look into another file hosting solution.

    Unfortunately not. I asked around and apparently there's really not too much that can be done to reduce the backlash in these boxes. It's engineered to have a certain amount of slop in the mechanism to allow for proper lubrication. That being said, I've heard of people shimming the worm gear downwards slightly (closer to the wheel), but I didn't want to risk breaking anything.
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  13. Archie

    Archie Eternal tinkerer

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    @Tim McGuire - I can host the files you in my Google Cloud Instance if you like?
    If they are not super large, email them to me support at fmit dot com dot au and I'll post a link to them here.
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  14. Zed

    Zed VR Simming w/Vive

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    Thanks, Tim. Noorbeast said the same thing. For me at least the down shimming is out. I may still see about shimming end play on the worm if there is any even at the expense of lubrication.
  15. Tim McGuire

    Tim McGuire "Forever a work in progress"

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  16. Brett Horton

    Brett Horton Active Member Gold Contributor

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    Thank you sir
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  17. Nick Moxley

    Nick Moxley Well-Known Member

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    Brett build 2, ill take one. ;)



    PS Tim, Freekin awesom job, somehow missed this project due to being absent but Stellar work bud. :thumbs:thumbs
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  18. Tim McGuire

    Tim McGuire "Forever a work in progress"

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    Much appreciated!
  19. Brett Horton

    Brett Horton Active Member Gold Contributor

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    I'm not following your "Spring_Preload_Mechanism" Drawing in Solid works.
    Can you splain? Do they wind the collective springs to pretension? Assume preset initial position upon assembly?
  20. Tim McGuire

    Tim McGuire "Forever a work in progress"

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    That was one of the parts that I still have to finish. Think of it like a screw jack for a car, as you turn the outside part, the inner part moves up and down to preload the springs. The part that the spring attaches was supposed to have an ACME thread cut into it, and the hollow bit that it slides into would have the corresponding female thread (I ran into problems trying to find a reasonable way to cut ACME threads without buying expensive lathe inserts). The timing belt is wrapped around the outside to ensure that all of the springs are preloaded equally. I also wanted a small electric motor attached to one of the drive pulleys to allow it to automatically calibrate to user weight eventually, but the mechanism was turning out to be much harder to actually build than I anticipated, so I decided to put it on the backburner for now:

    heave_module_lowered.PNG heave_module_raised.PNG

    What I ended up doing as a temporary measure was using a 1 1/8" nut, and a hollowed out piece of the corresponding threaded rod, which I turn manually to adjust the preload (it's a bit messy, just applied a fresh coat of grease to it):
    26241875_1912278552133959_367819321_n.jpg