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Advice for welding up the frame

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by JBoogie, Jan 25, 2018.

  1. JBoogie

    JBoogie Member

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    So I think I have decided on welding up a steel frame for my 2DOF seat mover. Is 1" 16ga square tubing going to be strong enough or do I need something bigger?

    thanks!
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  3. yellofella

    yellofella Member

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    hi there
    I'm not sure I can offer a direct answer to your question as you haven't given any idea on frame design or measurements. when you mention 1" 16ga square tube I assume your referring to 25mm square hollow section with a 1.5mm wall. If your 2 dof seat mover sits directly on the floor then yes I guess it will be strong enough for a seat frame and wheel stand but if you wish to add traction loss at a later date then u will probably find as I did that as the frame will then be supported from a swivel point at the front and rollers at the back and that the frame will deflect in the middle under your weight then straighten as u hit the brake. I use 50mmx25mm ( 2"x 1") with a 2mm wall for my side rails and rear bar then used lighter steel for most of the other parts to stop this.
    The most difficult part I found to welding up a steel frame for the first time was getting everything set out for my size ( pedals the right distance from the seat and steering wheel height, distance and angle) this is where aluminium profiles have the advantage as in un bolting and moving is better than cutting, re welding and re painting if you find the driving position to be wrong. It took me a week in the workshop working long hours to finally be happy with my frame at a cost of £200 for the steel here in the uk with delivery and £70 in paint.
    Ive added a diagram on the suggested geometry for a 2dof scn5 setup I used to build mine and adapted the design for motors trying to keep to the same measurements and connecting rod angles. Also a picture of my frame once welded and half way through painting. IMG_0027.JPG
    hope your build goes well and be happy to answer any questions you might have on the way.
    X-Sim Motion Base-no seat.jpg
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  4. JBoogie

    JBoogie Member

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    Thanks @yellofella yes 16ga is pretty close to 1.6mm. I have only been planning for a 2dof so far but you bring up a good point. It might be better to beef up the bottom frame in case I want to add traction loss later.
  5. frankrizzo2

    frankrizzo2 Member

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    I would go with 1.5 inch tubing. You might even get away with a lighter gauge for some parts. Of course it's a little trickier to weld lighter metal though. This is just my opinion and there are some amazing rigs on here to use as templets. Do your research and start welding. Worst case you'll have to grind your welds and move some things around. I use truck bed liner spray paint to paint with to hide imperfections. Good luck with your build!!
  6. JBoogie

    JBoogie Member

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    Do you mean 1.5” for the base frame? Is 1” 16ga enough for the seat frame? By seat frame I mean the part which mounts the seat to the u joint. The only part I was questioning is the part which extends up the back of the seat for a shoulder mount design. It seems like that butt joint would be subject to the most stress.
  7. yellofella

    yellofella Member

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    yes that butt joint will be under more stress than most of the other parts of the frame and using a beefier piece of steel there would be wise. I used 25mm box section 1.5 mm wall for the seat frame and 50mm x 25mm with 2mm wall box section for the back post the same material I used for the side rails. I tried to keep a common measurement of 25mm with all the steel to avoid overhanging steel on the joints. As for the welding @frankrizzo2 was right when he mentioned that thinner steel is trickier to weld. I found that using an arc welder had the advantage in being able to use different thickness welding rods for the weld I had to do, 1mm rod on 1.5mm steel and 1.6mm rod on the 2mm. if u need a stronger weld then clean up the first weld and weld over to strengthen it. once a join is welded put some stress on it once it has cooled and try to break the weld. if you cant break it by hand then its prob good enough for the stress a sim rig will produce. as mentioned there are loads of great sims on here to get an idea of what u want to build and look forward to watching your build progress.
  8. JBoogie

    JBoogie Member

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    Thanks @yellofella I see a couple different designs for that back vertical section so I’ll draw some up and post them tonight for feedback. I’ll be buying a cheap welder soon too. Unfortunately I don’t have the budget for a good one so it’s either a cheap stick welder or a cheap flux core one. I guess neither are ideal but good to hear you had success with stick.
  9. JBoogie

    JBoogie Member

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    So I would really like to weld this up myself, but unfortunately I don't can't stretch the budget to cover a $400+ welder! Does anyone have experience with the cheap ~$100 welders with thin steel tubing? I am looking at 16 or maybe 14 gauge for the most part. (I think this is around 1.6 - 2.0 mm) These cheap AC welders have good reviews on Amazon, but I'm curious is anyone on this forum has actually successfully used one of these. Here are a couple links:
    flux core:
    stick:

    thanks!
  10. cthiggin

    cthiggin Active Member

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    They will work for light weight steel / body panels etc., but don't expect to weld for a long time between "rests" of the machine. Most of these type welders are fine for the
    home diy'ers, but their duty cycle is low.

    For what you are doing, one of these type should work.
  11. JBoogie

    JBoogie Member

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    thanks for the reassurance! Thats what I assumed, but all the similar questions about these cheap welders on the welding forums get flamed so I wanted to get an opinion from a fellow hobbyist. Any feelings on stick vs flux core? (again, specific to this application)
  12. Lol4

    Lol4 Member

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    I used one of these. https://www.google.com.au/search?q=...biw=412&bih=652&dpr=2.63#imgrc=wB39eRxbcB5QIM:

    Cheap $100 odd bucks and worked really well. I had no welding experience before building this rig and with a bit of trial and error and using the steel mentioned in previous posts 1.5mm and 2mm thick square tubing it turned out well. I have had 110kg people thrown around on mine and is still holding solid. The welds are not always pretty but as long as they penetrate through properly you will be fine. You can also bolt as well as weld to be extra safe on high stress areas.

    Just remeber good ventilation and avoid breathing in any of the fumes. Would recommend a quality mask.
  13. cthiggin

    cthiggin Active Member

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    A "good" adjustable variable shade AND auto darkening welding helmet is where it's all at.
    A $ 100.00 unit / or / a $1000.00 unit - IF you cannot see properly, then it's an exercise in futility.
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  14. Lol4

    Lol4 Member

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    Totally agree. It is often over looked when buying a cheap welder. I spent about $90 on a proper auto darken helmet after messing around with the cheap provided one. It made a huge difference to the quality of the welds being able to see properly. Also most of these helmets have a grinding setting that will get a lot of use if starting out welding.
  15. cthiggin

    cthiggin Active Member

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    Lo14,
    Yes, your so correct on the grinding issue.......forgot to bring that up.
    In my early years, I had a small shard of steel hit me in the eye (went under the safety glasses).........Eye Dr. had to drill it out.
    One would NOT have that problem with the grinding feature on a good welding helmet.
  16. JBoogie

    JBoogie Member

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  17. Lol4

    Lol4 Member

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    That would seem to be fine based on the specs.