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2DOF Compact almost-no-weld aluminum build

Discussion in 'DIY Motion Simulator Projects' started by mayoms, Jan 8, 2018.

  1. mayoms

    mayoms New Member

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    I stumbled upon this community a couple of months ago and have become obsessed with sim-building. I spend more time thinking about/planning my sim (and future revisions) than playing the games I want to build it for! At any rate, I've posted a few questions in the FAQ/QA builders category, but am far enough along where a proper build thread feels appropriate. In my 'first-post' I outlined some of my needs, but I'll quickly restate them:

    1. Compact.
    2. Lightweight.
    3. Primarily for flight sim- but this community has definitely piqued my interest in racing.

    Right now I am looking at 2DOF. If I'm able to successfully complete this stage, I want to experiment with maybe modifying the chair to be a gSeat and/or have belt tensioners to simulate sustained G forces.
    Materials:

    Aluminum Frame

    I settled on square-tube and angle aluminum as a lightweight and easy-ish to work with medium. It's relatively inexpensive, can be found at my local building supply and I can cut it with my mitre saw with a regular blade. I didn't have access to a TIG welder, though, so it will primarily be assembled with bolts and rivets. I've purchased a bucket set on Ebay, and have started to assemble the frame:

    IMG_0715.JPG IMG_0712.JPG

    Here I have a 12x12" .25" aluminum plate bolted to the frame of the chair- the universal joint will be bolted to this plate once I have determined the COG. When attaching the plate I found beneath the pleather 4 bolts, that I assume were for attaching the seat sliding mechanism. I decided to attach this angle and tube aluminum to those bolts and built out the frame from there.

    I say this build is "low" or "almost no" welding because the only bit that will *need* to be welded will be the the universal joint, which will have a 4x4" steel plate attached to either side, and bolted to the post/seat plate. I'll expand on that later in this thread.

    Motor Controller:


    Arduino and Sabertooth 2x32

    I had an unused Arduino UNO laying around, and was originally going to use MotoMonsters, but after reading about the QA issues, I decided to go with the Sabertooth 2x32 because it seems to be pretty plug and play, and the manufacturer stands behind their product.

    Motors:

    I went with these, from the motor shopping section in the FAQ:

    https://www.ebay.com/itm/GEAR-MOTOR...LL-FEED-SIMULATOR-75-80RPM-50-1-/371596157992

    At first I was looking to do a lower cost wiper build. After doing much reading I decided that compactness was more important, and didn't the wiper motors would provide the needed torque for such a build, and went with these more expensive and 50:1 ratio gear motors. I got two 'left-handed' motors. Here is a shot of one them open, as I revered the shaft so they'd have 'opposite' hands:

    IMG_0711.JPG


    I'll keep posting here as the build progresses. Now that the holidays are over I have been able to find much more time to work on evenings and weekends.

    Attached Files:

    • Like Like x 4
  2. mayoms

    mayoms New Member

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    I've been working on power supplies lately. I have two HP DPS-600PB B power supplies I purchased on ebay for $30 (as a set). I followed @Slider's guide from the FAQ, and my motors appear to be in working order:



    So I am a bit concerned about power though - I am not sure how to attach two power supplies to 1 Sabertooth.

    In this thread the advice is just to join the +/- on both PSUs on the Sabertooth's terminals. Is this not essentially wiring the PSUs in parallel, and do I need to connect the grounds like this article mentions?

    https://www.xsimulator.net/community/threads/wiring-server-psus-in-parallel.6251/
  3. mayoms

    mayoms New Member

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    More work on the seat frame today. As I've mentioned, compactness is something that is important to me. So I've designed the seat frame to be modular- the footrest/pedal mount (and attached post), as well the mounts for my HOTAS/HOSAS controls will be easily removable and storable when the seat is not in use.


    So this will be the bottom view when the seat is not in use:

    IMG_0725.JPG


    And the (yet to be completed) footrest/pedalmount will slip in like so:

    IMG_0726.JPG

    I am looking for an easy way to secure this in place. I am thinking some sort of quick release pin, like this one:



    Or the type of 'pop-pin' you find in adjustable gym equipment. I found these:

    http://www.fullcirclepadding.com/catalog/cfProduct_Detail.cfm?c=1024&p=FW130T

    But I am still trying to figure out how it would work, given that I don't have the facilities to weld aluminum. At any rate, the frame is moving forward, and I am happy with how this is turning out. Once I have the seat frame assembled I can figure out the COG, which will aid in a couple of design choices I am stuck on for the base.

    Looks good so far, though:

    IMG_0727.JPG
    IMG_0730.JPG


    I am still hoping to get some guidance on my question above re: multiple power supplies to one sabertooth, if anyone has any experience there.

    Thanks to everyone for all your help.
    • Like Like x 1
  4. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    You can get bolts with knurled or smooth plastic ends so you can do them up by hand, or you could 3d print them, drill a couple of holes and you can easily quick release, similar to what I did here:

  5. mayoms

    mayoms New Member

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    Thanks for the tip @noorbeast - that's a good idea that may be the solution I go with.

    On another note, the completion of the seat frame is going to be somewhat delayed. I placed an order for MFG Crosswinds rudder pedals, which unfortunately won't ship until February 23. :( Based on all the reviews it should be well worth the wait, but it delays being able to fully assemble the seat frame and determine the COG. Fortunately there's quite a bit I can do in the mean time.

    I've thought about at a later date upgrading my HOTAS.. I assume this means I'll need to reset the COG on the chair? It'd also be nice to change the joystick position from the side to the center bar (depending on the sim I'm playing, it'd nice for it to be roughly where it is in the 'virtual cockpit'). This makes me think I should consider a 'variable COG' similar to the DX Racer.

    If I change my VR headset should this also require adjustment? If the helmet is balanced properly shouldn't the COG be roughly the same?
  6. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
    3DOF, DC motor, JRK
    You could ask what the weight of the pedals are and just add that to the pedal base for balancing, just so you can get on with it rather than wait.

    A VR HMD is neither here nor there in terms of weight.

    A different HOTAS may have a small effect if it is something like the Warthog, but as they are mounted closer to the COG in the first place do not have as much of a leverage length effect as the pedals
  7. mayoms

    mayoms New Member

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    Yeah - that is a good idea, and something I'd considered doing. However, since I've never used these pedals I am not sure what position I'd want them in, and this affects the design and amount of material used and therefore the weight. So I think I am just going to hold off until I get the pedals.

    That's okay though, there is much to do. I've been working on the base this weekend. I've decided to _not_ use the steering column u-joint I mentioned in another thread... and to take a small risk and use @Hoddem's 3d printed flanges. I did see his comments mentioning that they were designed for actuators and not the seat joint, so I am going to take some additional steps in attempting to strengthen the joint:

    1. Denser infill - I think I've seen folks printing at 50% for actuators. I am going to start at 60% and increase as needed.
    2. I'll be printing thicker layers - I've read several places that there is as much as a 24% increase in overall strength between a .3mm print and a .1mm print.
    3. I am going to try 1 and 2 first, and then experiment with annealing the print. I've read about boiling and also baking prints, and overall I think this article that describes using a 'sous-vide' seems to be a really solid method:

    http://justinmklam.com/posts/2017/06/sous-vide-pla/

    The problem here is that there is some change in the shape of the print when heated, and since this is a mechanical device with moving parts - that is of course, 'not good' (tm).

    I might experiment with fully assembling the joint and flanges, hoping that holding everything together around the u-joint will help keep that shape in tact, and therefore the movement.

    At any rate - I know it's a risk, but I like 3d printing things and seeing what I can get away with doing - and if this works, this wold become a no-weld build. Also, I can just buy metal flanges if the 3d printed ones fail. At $40-$50 a pop, though, I'd love to avoid it.

    Nothing to show are far as pictures-- next weekend I plan to do some assembly, so I'll post some new pics them.
    • Informative Informative x 1
    Last edited: Jan 28, 2018
  8. mayoms

    mayoms New Member

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    It has been a while since I've updated on the build, but I have made progress. I received the MFG Crosswinds Rudder pedals a few weeks ago, and have completed most of the chair frame and a good bit of the base. Since I am using the 3d printed universal joint, which is about 4.5x4.5", I decided to go with a 6x6x.25" square tube for the seat base:


    IMG_0785.JPG

    The u-joint model, I think, assumes that the u-bolts will be cut flush, but I decided for a bit of extra strength to cut through, and there is a nut clamping the u-bolt to to the u-joint flange, and then another fixing it to the plate:

    IMG_0786.JPG

    Here is everything connected:
    IMG_0788.JPG

    Hand-tighten bolts, so I can remove and store the pedal-board:

    IMG_0790.JPG IMG_0791.JPG

    Chair with rudder pedals:
    IMG_0793.JPG

    Chair with rudder pedals and stick:

    IMG_0795.JPG

    I was able to attach the VESA mount I currently use with my hotas/office chair, to the chair frame, which saved me a bit of time. I don't have a more close up photo of this, but can post if ayone is curious.

    Next steps:

    1. Get a buddy to help me work out the COG for the chair.
    2. I've got a better 3d printer on order (have a MP Mini V2, getting Prusa I3, man this hobby ballooned into something else), and will probably reprint the u-joint flanges in NylonX or something else that's quite strong.
    3. Work out power and electronics: while I was waiting for my pedals, I started playing with the Arduino I've had laying around for a couple of years, and familiarizing myself with writing sketches, and doing some basic circuitry. I need to start translating that knowledge into the sim.
    • Like Like x 2
  9. Stouuf

    Stouuf Member

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    Good work ! :)
  10. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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  11. prodigy

    prodigy Burning revs

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    My Motion Simulator:
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    Man, you don't know what you got into :grin

    I have started like about 5-6 years ago with simple thinking "Hmmm, let me try building this cheap 2DOF wiper motor sim".. After doing that, I immediately started on one upgrade, then on another upgrade, then building the whole thing one again from scratch with new equipment, and that never stops. Basically putting thousands and thousands of Euros into simrigs since beginning :grin