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  1. #1
    la vache fantôme phantomcow2's Avatar
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    Adding stiffness to this parallelogram

    Imagine a parallelogram. It is made from aluminum extrusion for the longer legs of it, and aluminum plate for the sides.

    __________
    |_________|

    I believe with the loads this will see, this parallelogram will try to make more of a rhombus

    ________
    /______/

    That is not acceptable. I was thinking just get a plate to mount in the back of this parallelogram, that would add excellent resistance to twisting. But, though my stock pile is pretty good, its not that good!

    So my thoughts were to add angle supports, like this

    ===========
    ||/\/\/\/\/\/\/\/\||
    ===========

    Except these angle supports would actually be touching the other material!

    So my question is, what would be the angle of these angle supports to maximize resistance to deforming?

    THis all has to be much more overbuilt than I had expected, for all I know I might have a 4HP motor in the middle of this...
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  2. #2
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    Just went I thought I was logging into foo to unwind from a busy day, you throw this at me?

  3. #3
    Hazardous Taerom's Avatar
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    Oh man, I'm not even gonna try to help you on this one...no clue

  4. #4
    la vache fantôme phantomcow2's Avatar
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    There must be some mathematical way to figure this out. I've not taken physics or statics and dynamics yet
    C://dos
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  5. #5
    later free_pizza's Avatar
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    Quote Originally Posted by phantomcow2
    I've not taken physics or statics and dynamics yet
    wanna buy my statics/dynamics book? its barely used! (my transcripts will back me up on that)

  6. #6
    2-Cyl, 1/2 HP @ 90 RPM slvoid's Avatar
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    Use a thin matrix of honey combs. It's the strongest structure for the most volume inside (meaning the least amount of material for the walls).
    Or stick a couple of arches in there, also one of nature's strongest forms.
    Why use your brain when you have 2 billion years of evolution behind you?

  7. #7
    2-Cyl, 1/2 HP @ 90 RPM slvoid's Avatar
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    I'm beginning to think this guy's the Merton of engineering..

    Quote Originally Posted by blonduathlongrl
    Just went I thought I was logging into foo to unwind from a busy day, you throw this at me?

  8. #8
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    45 degrees

  9. #9
    SERENITY NOW!!! jyossarian's Avatar
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    Jeez, what good is cereal gonna do?
    HHCMF - Take pride in your ability to amaze lesser mortals! - MikeR



    We demand rigidly defined areas of doubt and uncertainty!

  10. #10
    la vache fantôme phantomcow2's Avatar
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    Quote Originally Posted by slvoid
    Use a thin matrix of honey combs. It's the strongest structure for the most volume inside (meaning the least amount of material for the walls).
    Or stick a couple of arches in there, also one of nature's strongest forms.
    Why use your brain when you have 2 billion years of evolution behind you?
    Thanks, I was hoping for a reply from you.
    By Honeycomb, do you mean something like this?


    As for the arch, I see that more as a resistance for loads as if a person was pushing from ontop. The extrusion is very solid, plenty to resist this. I dont see much how the arch would help this thing from turning into a Rhombus.
    THe honeycomb idea is great, might be a little complicated to make, but I think it could be done...
    C://dos
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  11. #11
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    estimate the loads in both directions, one load going straight down, one load going to the right. Lets say the load is 4 down, 3 to the right, so the hypotenuse would be 5. The angles here would be 36.87 and 53.13.
    That should work. Just don't put a 5hp engine in.

  12. #12
    SERENITY NOW!!! jyossarian's Avatar
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    Make sure it doesn't go past 400 watts or it'll drop you like a poser and you'll never catch it.
    HHCMF - Take pride in your ability to amaze lesser mortals! - MikeR



    We demand rigidly defined areas of doubt and uncertainty!

  13. #13
    la vache fantôme phantomcow2's Avatar
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    Well it wont be an engine really, it would be a wood router. I have a 4HP servo motor that I might try to use for a spindle, I am overbuilding everything just incase I use that someday
    C://dos
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  14. #14
    By-Tor...or the Snow Dog? hi565's Avatar
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    Quote Originally Posted by slvoid
    I'm beginning to think this guy's the Merton of engineering..
    Difference: PC has an idea what he is talking about
    ----------------------------------------------------------

  15. #15
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    Quote Originally Posted by slvoid
    I'm beginning to think this guy's the Merton of engineering..
    whoa!!! that was a little harsh..

  16. #16
    2-Cyl, 1/2 HP @ 90 RPM slvoid's Avatar
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    Quote Originally Posted by hi565
    Difference: PC has an idea what he is talking about
    Then he'd be the one giving answers. :-p

  17. #17
    la vache fantôme phantomcow2's Avatar
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    Well, like i've said, I have not taken a physics course yet or anything like it (signed up for next year). I want to build this thing right the first time, so this project has dragged and dragged on as I gather parts, knowledge, all of that. The frame of this SHOULD be done in 2 weeks.
    ALl .5" anodized black aluminum, except .75" in some places. Should be rock solid...
    C://dos
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  18. #18
    Should be riding Bike Lover's Avatar
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    45 degrees
    Agreed. You'd essentially be creating a truss- very strong. That's why you see them in all the large buildings...

    Oh, and it'd be statics you'd want for the question...

  19. #19
    Non Tribuo Anus Rodentum and off to the next adventure (RIP) Stacey's Avatar
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    Plate gusset the corners or truss your parallelogram with tube

  20. #20
    la vache fantôme phantomcow2's Avatar
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    Yea 45 degrees was my plan, I wanted to see if anybody else would agree. I've also heard 30 degrees suggested, but for 30" unsupported length with two parallel bars that are 9" apart, i think 45 is better.
    Maybe one of my teachers has taken statics and can help
    C://dos
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  21. #21
    la vache fantôme phantomcow2's Avatar
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    Quote Originally Posted by Stacey
    Plate gusset the corners or truss your parallelogram with tube
    Already got the Gussets
    C://dos
    C://dos.run
    run.dos.run

  22. #22
    Senior Member FXjohn's Avatar
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    simply connect the corners diagonally. Make an "X"
    Comedian Bill Hicks once said, "Money can't buy happiness, but it can buy a jet ski, and you never see an unhappy person riding a jet ski."

  23. #23
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    Honestly its not going to matter, aluminum is stiff as hell and either 30 or 45 will work for that application.

  24. #24
    Specialized Member ChAnMaN's Avatar
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    wrap in in duct tape, the strongest material in the universe
    You can never be too Specialized
    Click here if any of the following apply to you:
    1 You dont like Specialized, 2 You drive a SUV, 3 Your name is George Bush

  25. #25
    Hazardous Taerom's Avatar
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    Quote Originally Posted by ChAnMaN
    wrap in in duct tape, the strongest material in the universe
    +1

    duct tape for the win!

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