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Question Is this u-joint big enough (images attached)?

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by mayoms, Dec 6, 2017.

  1. mayoms

    mayoms New Member

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    So I picked up this u-join online- it's from the steering column of a 93 Mustang:

    IMG_0697.JPG IMG_0696.JPG

    It's a bit smaller than I expected. It seems like folks are using much bigger joints, maybe from a different part of a car. Has anyone built a frame mover with this sort of joint?

    I think that if properly welded, it'd probably take the weight of me, my frame, and chair. I am doubting myself because I haven't found any examples of folks using anything that looks to be around this size.
  2. Archie

    Archie Eternal tinkerer

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    Hi, You may have success with that. I'm seen builds using the U-Joint from the Steering column of a Land Rover (Can't find the link at the moment)

    Chances are, if it's in a car, it's been engineered beyond what we could throw at it :)
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  3. PiaMan

    PiaMan Active Member

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    The srock simxperince joint is about that size. As long as no side to side play you should be fine
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  4. mayoms

    mayoms New Member

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    Thanks to both of you for your input. Glad to hear this is going to work.
  5. Gadget999

    Gadget999 Active Member

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    My Motion Simulator:
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    i used a steering joint and in my opinion it was not stiff enough

    however - i managed to get rid of the flex using a pan hard bar
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  6. mayoms

    mayoms New Member

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    @Gadget999

    Can you give a bit more detail? How specifically was it not stiff? I found your post about it here:

    Formula 3 simulator :)

    You said you were getting some twist in the front? Does that mean there was some unexpected yaw, putting improper pressor on the rod arms and motors? Do you have a pic somewhere of the pan hard bar fitted, by chance?

    In the images you posted here:

    Formula 3 simulator :)

    The rod that the u-joint is mounted on seems quite a bit smaller than what I was imagining. Something like this:

    u-joint-placement.png

    The 75mm base would probably be steel, but possibly a ticket aluminum. Either way the bottom of the u-joint will be welded to either a steel cap the is bolted to the aluminum, or welded to the steel base. The black line at the top of the u-joint is a 75mmx75mm steel plate that will be bolted to an aluminum plate or some other mechanism to attach the chair.

    I am wondering if maybe a more robust base might counteract the twist you were experiencing? The joint itself seems quite solid.
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  7. Gadget999

    Gadget999 Active Member

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    yes there is some twist in the front of the sim - i used part of the steering joint to raise the sim up a bit, this thin rod is part of the problem

    you would not believe a steering joint would have so much twist - but i guess i am applying much greater forces than it was designed for

    I think your joint is strong enough, if you have a problem you can fit a panhard bar later on
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  8. Zed

    Zed VR Simming w/Vive Gold Contributor

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    That was what also happened to me except it was my mounting on the steering U-joint I used that allowed the top part of my platform to rotate about the U-joint. It was a bolt with a bolt coming in from the side to lock it and it just wasn't strong enough. I added two Panhard bars and no problems at all now. It's rock steady. You can see them in the photo - the two thin black rods on a slight diagonal front to back with rose joints on the ends. The top/rear attaches on the top frame right in line with the U-joint pivot, and the lower/front attaches to brackets on the lower frame. The geometry is basically totally correct for pitch but not for roll. There is a minor mismatch that technically should (and probably does) introduce a tiny amount of yaw when the top platform rolls but it's not noticeable. As the top platform rolls, the Panhard rods then trace a small angle arc with the center/vertex of the arc at the front where they attach to the bottom frame. The yaw goes with the cosine of the angle if that matters for an explanation. That's where the yaw comes in but again, not noticeable. The rods have a very small amount of slack in them so are only active in tension which is why I put one on each side. Whichever way the top platform tries to yaw, a rod goes into tension and stops it. They are only 1/4-20 all thread rods that I used and then put some wire loom plastic over them to dress them. This setup let me use a pretty small U-joint, have the pivot right under the seat to keep the roll and pitch from having much translation added in, and still not have to deal with the U-joint having to resist any twist since the Panhards take all of that. (Older image before I went to smooth piping on the wind generator.)

    [​IMG]
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  9. gSeat

    gSeat Member

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    If you search the internet for "xj650" and simulator keywords, someone used motorcycle u joints successfully. Don't want to post the link because not sure if appropriate as it's a different forum.

    I asked about any concerns here: https://www.xsimulator.net/community/threads/u-joint-motorcycle-vs-car-truck.11112/, and like @Archie said, these are designed for moving vehicles, so I'm going to give the motorcycle u joint a go. Why? Less mass than a regular u joint, that much lighter for whenever I break down the sim to take it somewhere. 100% sure at least 2 times per year I'll be take it places, and whenever packing/breaking down gear, every bit of convenience comes into play for me. In addition, many motorcycle ujoints already have a 4 hole plate built in, so you'd only have to take care of the other side. I'm still contemplating possibilities of addressing the "hollow" side without welding for no particular reason.
    Last edited: Dec 9, 2017
  10. Archie

    Archie Eternal tinkerer

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    @gSeat - Good find! You could get two of them so that you can take them apart and make sure both ends have the flange for easier mounting.
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  11. gSeat

    gSeat Member

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    Archie, that's an excellent idea, you may have just addressed the "hollow" side...I'm so curious, will order a second one and see how taking it apart works, thank you!
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  12. gSeat

    gSeat Member

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    Maybe should have made a different thread...here seemed a good place to continue though..

    It's always a head shaker when looking at things from various angles, and missing the simplest solution....until your comment, my brain didn't wake up(take apart the u joint, add another flange, duhhh)...so I'd been thinking of "filling in the hollow" with a 3d printed plate, but your solution just made basic sense, so ebay search found 2 flanges, buy 1 u joint...of any type, like a spicer flange/yoke model and pop them together.

    However, been wondering about an entire 3 printed u joint with high tensile not so shattering type of material, reading up/watching vids and checking into 90% metal filament or even the 20% with something stronger than PLA. It seems polycarbonate and some other hybrid mixes of non metal may even suffice if reinforced otherwise.

    Anyway, again, used up time searching around for 3d u joints until finally searching xsimulator....once again, people have already done both of the above, including 3d printing the whole unit practically. Thank you a TON @Hoddem who posted data files and details on 3d print joint in the posts over at 6 DOF from scratch ...

    @Hoddem said,
    So it'd be intersting if Hoddem could provide a note if the joints were actually implemented and how they worked out beyond the stand test? In any case, I'm just going forward with a 3d printed system with metal joint, but instead of regular PLA, will use something stronger/reinforced.

    +100 vote @Hoddem's post for a place under U joint info the FAQ.
  13. Hoddem

    Hoddem Active Member

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    Keep in mind, my u-joint was designed to used with linear actuators which wont have nearly the twist force that a single joint under a seat will have. That being said, it is pretty strong and could be made even stronger if needed, increase the fill density and move to a stronger material like nylon or carbon fiber filled. If I were doing a seat mover with a single u-joint I would probably pay the money and just buy the parts to build a double flange u-joint. being that you are only buying 1 set it wont set you back too far. I would take a look at www.driveshaftparts.com I started down this road, but at $40 each and needing 6 u-joints it got too expensive.

    2017-12-14 11_03_05-Greenshot.jpg
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  14. gSeat

    gSeat Member

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    Ah, thanks for the clarity, guess I'll go the double flange route, but may end up testing a 3d print later for pure curiosity reasons (trying to make this during December break, and with the new stronger materials and greater infill I'm almost positive it'd work, who knows. Forgot to ask if you used special tools for your u joint fittings (for snap rings or any other purposes), or just needle nose or something?