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Motion Sim w/ Surge & Traction Loss

Discussion in 'DIY Motion Simulator Projects' started by Boomslangnz, Oct 26, 2014.

  1. Boomslangnz

    Boomslangnz Active Member SimAxe Beta Tester Gold Contributor

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    Hi guys,

    I am looking at converting my current sim to 2dof motion

    [​IMG]

    Currently looking at building a new base with pivot point under belly button position while racing. With 12v 200w worm gear drive motors either 50:1 or 60:1. Either attaching arms to rear of seat or rear of top sim itself. Will start getting parts soon but plan is to build this fully early in the new year. Shifter position will change aswell as removing the table and will need new brace put on it for pivot to attach too.
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  2. Ads Master

    Ads Master

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  3. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

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    Good plan @Boomslangnz.

    Best way to find a pivot point is grab a mate, put the rig on a roller with yourself in it and move the whole lot until it balances. With a full frame and screen it could be a good deal further forward than where you expect. You put a great deal of strain on the motors in a poorly balanced rig so it pays to do it right.
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  4. Boomslangnz

    Boomslangnz Active Member SimAxe Beta Tester Gold Contributor

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    My Motion Simulator:
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    im trying to work out the gear I need but as far as I can tell I need

    2x 200w Worm gear drives with either 50:1 or 60:1 ratio (not sure where I get these)
    2x Pololu JRK 12v12
    Universal Joint or Similar for Pivot
    12v Power Supply to power the motors
    Arms to attach between motors and sim
    2x 4.7k or 5k ohm potentiometers with continuous turn

    Anything else im missing?

    I believe I need fans etc to cool the gear....does it matter if arms attach to back of sim itself or is it best to try attach to back of seat. Not sure if it really would but Id obviously like to get the best torque on it is possible
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  5. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

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    That is pretty much the basics @Boomslangnz.

    A little while back @Avenga76 posted this link for a New Zealand motor supplier: http://www.bgts.co.nz/styled-2/styled-10/index.html

    The JRKs simplify things and there is good info re setting up in the FAQ section

    For a cheap option have a look at modding HP PSUs that @Slider put together, one per motor and very cheap on ebay: http://www.xsimulator.net/community...-server-power-supply-for-12v.5774/#post-60617

    You want a pretty robust mount so consider bracing the seat to the frame upright locating the arms on a T strut around shoulder height. Leaver CTC length will affect how wicked the movement is, @eaorobbie goes for the radical end of the scale 60-68mm while myself and others are more conservative at 40mm CTC.
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  6. Boomslangnz

    Boomslangnz Active Member SimAxe Beta Tester Gold Contributor

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    cool thanks a lot

    Im getting a little curious about adding drift to it aswell. Is it quite simple to add? from what I gather I need a point at front and simply have the rear slide left and right from that point with an actuator pulling and pushing (to get the left and right).

    Is that it? or is there a lot more too it haha
  7. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

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    My Motion Simulator:
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    You can get a good idea of construction of 3DOF traction loss by having a look at @Al.Bundy project. You can also use a cheap lazy susan as a front pivot plate as @Nick Moxley has done. If you want you can start with 2DOF and add the traction loss later, basically by adding a sub frame, motor, JRK, psu...etc
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  8. bsft

    bsft

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    mount the motor connections as high as you can, if need be, make up a t bar behind the seat to shoulder height at least. You have a lot of weight to over come, so going up above centre of gravity is the key here.
    I will find a link later for the motors, they can be found on eBay under crabpot saw mill motors. Try not to go of more than 45mm ctc levers as you need as much torque as you can use .he immersion factor will still be there, even if actual overall throw is not massive.
    Best get the 2DOF sorted first and moving right, then look at 3rd DOF a bit later.
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  9. Boomslangnz

    Boomslangnz Active Member SimAxe Beta Tester Gold Contributor

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    would it be much better to have a lighter frame? I could always start from scratch to try lighten the weight
  10. bsft

    bsft

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    it might help, however, a TV is between 5-10kg and thats quite a bit of weight up high. And also taking into account your actual weight as well. Your head may weigh near the same as a TV, but most of your weight is lower than the TV, so even 5-10 kg extra that high will move, but you need to consider re-enforcing the TV mount as well to stop flex.
    I did built a PVC pipe full frame a while ago and motioned it.
    The frame was lighter than steel and very sturdy, but again, I didnt have a TV on it .
    pvc1.jpg
    As Mario found out as well as another guy , lee, screens , no matter how light can be moved, but the problem is that you are trying to move extra weight higher on the frame.
    Both guys ended up taking the screen off and making it still.
    That being said, again, frame design will need to be taken into account of how you plan to motion it.
    If you use a really light seat like under 10kg, that will help.
    I think maybe you could look at mounting the connecting arms at the front, again up as high as you can , like behind the TV.
    Remember, with a full frame, it will flex under motion, and from experience I found it needs a LOT of extra steel to re-enforce it to support it.
    You could support the whole thing on a bit of 19mm plywood to stiffen it up. Heres my suggestion
    Driving_Simulator_0177A.JPG
    Mount the motors at the front but up right behind the tv, re-enforce the TV mount part and toss the whole frame on a sheet of ply, then pivot under that for balance point.
    Maybe that helps a bit.
    Cheers, David.
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  11. bsft

    bsft

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    yes but Robs is a seat mover, not a full frame.
  12. Boomslangnz

    Boomslangnz Active Member SimAxe Beta Tester Gold Contributor

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    hmm okay that's a bit diferent to what I was planning. I was under the assumption the motors are always best behind the seat and add a T bar or such behind seat with arms connecting up high. Also the whole sim is welded together with steel and I would be very surprised if it couldn't handle the motion. However If you think it needs the ply then ill add it
  13. bsft

    bsft

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    with your frame, roll it on a broom handle and see how it flexes, if its sturdy enough on its own, you are set. If it flexes and bends, then you may have to re-enforce it somehow.
    Any frame will handle motion, its how it flexes is the thing.
    My suggestion about connecting to the TV is that the TV is the high point of extra weight. It may help motion it from that point as you are working with the higher point of weight.
    You can put them behind the seat no problems as well. Just remember that the TV mount may flex and you may have to strengthen it.
    I found from builds I have done, to overcome full frame flex, I cheat by putting motors at the front to help support the frame. But behind seat is best option overall.
    I though with the TV being the extra high part in weight, it would make sense to motion it from that point.
    I recall @nclabs , I think did that with a 3 screen rig, mounting the actuators at the front behind screens.
    Anyhoo, prove me wrong! :)
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  14. Boomslangnz

    Boomslangnz Active Member SimAxe Beta Tester Gold Contributor

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    @bsft

    Thanks for your input. It might sound silly but are those worm gear drives going to handle moving me okay? Is it even possible to add more then 2 motors eg 2 at shoulder at rear and 2 at front as per your tv idea? Would this benefit in any way?
  15. bsft

    bsft

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    yes 2 of those motors will do it, heres Lees with 25:1 boxes, but internals are plastic. So under great strain they may fail over time. Although I have not had that issue.
    Shoulder mount at rear.

    however he chewed out gearboxes, so I suggest 50:1 or 60:1 with yours as the internals are metal.
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  16. bsft

    bsft

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    these days he uses 3 projector screens, and really sets the profile to throw him around.
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  17. Boomslangnz

    Boomslangnz Active Member SimAxe Beta Tester Gold Contributor

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    wow....that is AWESOME.
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  18. bsft

    bsft

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    which video?
    stronger gearboxes are cheap insurance for longer life sim action
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  19. Boomslangnz

    Boomslangnz Active Member SimAxe Beta Tester Gold Contributor

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    well both to be fair. But love the 3x projectors for the lack of bezels etc while his actual motion from first video looks really cool as well.

    Ive spent all afternoon reading posts on here and loving all the jobs. Every project seems to have their own differences of course and it's interesting seeing them all.

    Ill definitely go for the stronger gearbox.
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    Last edited: Oct 26, 2014
  20. Boomslangnz

    Boomslangnz Active Member SimAxe Beta Tester Gold Contributor

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    What is the Leaver CTC length? I mean what does that actually mean. Is it the movement the bracket off motor can move around?
  21. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

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    It is the center to center hole measurement on the lever that attaches the motor shaft to the leaver arms that move the rig.
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