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Truss on crank lifts

Discussion in 'Lighting and Electrics' started by Daveslights, May 19, 2008.

  1. Daveslights

    Daveslights Member

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    Hey all,
    I've got two Applied 11' crank lifts, currently using t-bars but we're looking to replace those with box truss. What would be the best way to go? I'd want to put 6 movers (technobeams, maybe mac 250's??) on the truss.
    My questions are:
    What lengths of truss would be ok to use? 2x5' seems to be a bit short, is it safe to use 2x8' bolted together?

    and i'm assuming that the lifts would need to be centered under each piece of truss, correct?
    The load would be between 210lbs and 330lbs

    thanks
     
  2. Van

    Van CBMod CB Mods Premium Member

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    Hmmm smells vaugely of Rigging.
    Not a good way to answer that question without violating the TOS. I'm sure there are several folks around here that can answer that question, but for liability reasons we simply can't. Sad I know, but true. I'm sure if you get in touch with any dealer, they can give you the ratings and specs on the truss you're looking at. They can usually supply you with a chart showing the load ratings for a given piece(s) of truss at various spans, as well.
     
  3. Daveslights

    Daveslights Member

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    sorry about that, forgot about the rules!
     
  4. Van

    Van CBMod CB Mods Premium Member

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    Darn Those pesky rules ! :mrgreen:
     
  5. Daveslights

    Daveslights Member

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    PM's appreciated!
     
  6. zac850

    zac850 Well-Known Member

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    Hey, tie line has a tensile strength of 100 lbs. If you use 4 pieces of tie line then it should be fine!

    Right? Isn't that how rigging works?
     
  7. MNicolai

    MNicolai Well-Known Member Fight Leukemia

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    Hehe, I'm envisioning four/five movers strapped onto tieline, and just out of the blue a fly comes along, oh-so-carefully lands on the tieline, and the entire rig collapses.

    Reminds me of the old Pinto. If you came to a stop and there was a bug following you, if it suddenly crashed into your rear bumper the entire car would ignite.
     
  8. avkid

    avkid Not a New User Fight Leukemia

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    NO!!!!!!!!!!!!
    -
    L11's are rated for 200lbs maximum at 10 feet 6 inches.
    If you get an imbalance and it throws the load, even partially onto one tower you are done for.
    -
     
  9. len

    len Well-Known Member

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    To avoid talking about rigging in public check your PM.
     
  10. zac850

    zac850 Well-Known Member

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    Not knowing any of the specifics of your equipment, make sure, 5:1 safety factor, please. Just because something is rated for X much weight doesn't mean you should ever load it to anywhere near that.
     
  11. photoatdv

    photoatdv Active Member

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    I thought tie line was rated to 500lbs? Am I wrong?

    Though I did see several pieces snap clean through when some genious decided to fly out the projection screens on my last show. That was a real mess (the screens only weighted about 20lbs, but they didn't fit between the battens on the sides of them.).
     
  12. avkid

    avkid Not a New User Fight Leukemia

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    I believe that was sarcasm.
     
  13. Van

    Van CBMod CB Mods Premium Member

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    Of course it was sarcasm, Everyone knows tie-line has a wsl of 20k pounds.
    :rolleyes:
     
  14. zac850

    zac850 Well-Known Member

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    Exactly, the only thing stronger in the industry is gaff tape!
     
  15. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Some posts from this thread have been moved to the Strength of Tieline thread.
     
  16. Dustincoc

    Dustincoc Active Member

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    [imgl]http://www.roadie.net/portal/html/uploads/photos/1177.jpg[/imgl]
    http://www.roadie.net/portal/html/uploads/photos/1177.jpg

    zip zies work Too. :evil:

    ALWAYS USE ONLY Grade 8 Bolts/Nuts/Washers, or other Manufacturer-Approved Hardware, when connecting truss!
     
    Last edited by a moderator: May 22, 2008
  17. JD

    JD Well-Known Member

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    I am speechless!
    Was it an attempted suicide?
     
  18. SHARYNF

    SHARYNF Well-Known Member

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    Not sure this is really a rigging question. Truss on Crank up stands starts at the entry level dj LEVEL and works up

    Basic logic says you need to have the truss extend from one stand to the other, your stands manufacturer will have a truss mount connector. Global truss makes the one I am familiar with. So a tbar configuration is definitely OUT.

    I usually look at Rigging as configuring a special setup for hanging etc, and not to include the pretty common off the shelf stands and truss setup.
    Sharyn
     
  19. avkid

    avkid Not a New User Fight Leukemia

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  20. TimMiller

    TimMiller Well-Known Member

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    your best bet is calling the manufacturer and asking them. I personally would never use something that light duty to hold a bunch of movers. If you span truss, you have to take in the weight of the truss, cableing, and fixtures. Then muliply that number by 5. now since those stands are rated for 200 lbs, you have a theroetical max weight capacity of 400 lbs. you can then carefully span your instruments across the truss. When i do this I use much mroe heavy duty lifts, but i also put some fixtures on the outside of the lifts also to counter balance the center smile in the truss. But once again, this is only a story of what i have done, and i'm not saying do what i say or do what i do. Just talk to applied, they are very friendly and helpful people, but this does give you an idea.

    Now the disclamer.
    NO one is responsible for what you do except for you.
     

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