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Question Aluminium Extrusion - how thick?

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Cripple, May 15, 2019.

  1. Cripple

    Cripple New Member

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    Afternoon,

    I am considering using Aluminium extrusion for the framework of my simulator. Mainly as I don't weld, and outdoors is 40ft down a narrow spiral staircase if I did. I also like the idea of being able to tweak the prototype.

    Question is though, what type? Would the 30mm x 30mm be adequate, or should I go for 4040?

    Thinking for a 2-dof, full-frame, flight sim, with 95kg pilot, rift headset, controls, and lightweight (hardboard & foamcore) switch panels. Say 110kg +/-? 1400mm x 600mm base dimensions of mobile section?

    Ta.

    (Edit: Simkits seem to favour le 4040, oui? Sorry, but I don't have the privileges to link to their site.)
    Last edited: May 15, 2019
  2. dododge

    dododge Member Gold Contributor

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    40x40mm is typical for sim rigs, often with 40x80 or even 40x120 pieces where you're worried about flexing or just want more attachment points for brackets.

    I currently use 1.5x1.5-inch and 1.5x3 (basically identical to 40x40 and 40x80) for primary framing, and some 1x1-inch (around 25mm) pieces to attach the pedals and wheel.

    I mainly use the 1x1 because it's thinner and lighter and I already have a lot of it lying around from other projects. I definitely would not recommend using the 1x1-inch for an entire rig. Long pieces will twist too easily, and the joints between them can flex. You can solve that by bracing it, but that ends up complicating the design and adding weight. The 30mm is probably not as bad, but it'd be better to just use the 40mm from the start. If you have concerns about weight, I think most manufacturers offer "light" versions of their extrusions that have the same outer dimensions but use less material.
    • Like Like x 1
  3. Zed

    Zed VR Simming w/Vive

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    My Motion Simulator:
    2DOF, DC motor, JRK
    I used 8020.net 1” x 2” extrusion in a 2' x 4' frame for the base of my sim with a 2" x 2" square cross member to support the universal joint that supports my top full frame motion part that’s made from 1" x 2" under the seat but the rest is 1" square tube. Strength isn’t any problem at all for the rig I built with it.

    https://www.xsimulator.net/communit...-20-strut-jrks-wind-flying-driving-rig.11281/

    8020 also has a deflection calculator if you want to verify your design: https://8020.net/deflection-calculator
    • Informative Informative x 1
  4. dododge

    dododge Member Gold Contributor

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    In my experience torsion is a bigger issue than deflection. I seem to feel a little bit of springiness even when just trying to twist a piece of 1010 with my bare hands (about 4' apart). On my old 10-series rig, what happened in practice was that the base pieces along the sides twisted a little bit which allowed the vertical pieces holding up the wheel deck to tilt left and right, and ended up with the wheel deck moving from side to side at the top. Stopping that would require some sort of cross-bracing, which could end up in the way of your legs.

    In your rig using 1020 instead of 1010 probably helped a lot. You've also got solid panels bolted into several of the rectangular frames which would brace them against the sort of flexing I ran into.