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Flyable grid

Discussion in 'Scenery, Props, and Rigging' started by peacefulone61, Dec 5, 2016.

  1. peacefulone61

    peacefulone61 Active Member

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    I am fairly new to my new theatre home and my predecessors Were not the best at taking and keeping notes.

    That being said , we have a flyable grid with a cable wire run to a single motor. I first am looking for guidance for how often and who should be inspecting/servicing the system? second how to figure out the max load and if it has to be balanced?

    I will admit outside of one class as part of my major in college quite a few years ago I really have not had much in the way of exposure to these types of systems. so I might not have give you all of the information you might need or even be asking the right questions.
     

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  2. BillConnerFASTC

    BillConnerFASTC Well-Known Member Premium Member

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    OK I give up. Whats a flyable grid? Especially one on one lift line.

    General motorized stage equipment that is used for overhead lifting should be inspected annually. The looks of this suggest to me it probably is ancient in terms of motorized rigging and not designed to any current standard and very well maybe should be taken out of service. A picture of what it's lifting would help.

    You need to have this looked at very soon and without knowing more, probably should not allow occupants under the load or loads or whatever it's holding up.
     
  3. peacefulone61

    peacefulone61 Active Member

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    Sorry it's a flyable lighting grid
     

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  4. peacefulone61

    peacefulone61 Active Member

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    What kind of company should I be contacting for inspection?
     
  5. Amiers

    Amiers I wear 6 headphones. I'm that Good!!

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    That whole rig runs on one wire and one motor?
     
  6. peacefulone61

    peacefulone61 Active Member

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    Out of the wire attached to the motor comes the wire splits to two lines then three lines per each beach for a total of six lines which feed six pullies three per side. I spent the day climbing through the rafters trying to understand how it was put together.
     
  7. egilson1

    egilson1 Well-Known Member Premium Member

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    Shameless plug. We (ok, I) at ALPS do rigging inspections. You can reach me via email at [email protected] or 781-437-1134.
     
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  8. peacefulone61

    peacefulone61 Active Member

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    Emailed
     
  9. BillConnerFASTC

    BillConnerFASTC Well-Known Member Premium Member

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    That one 2 hp motor lifts the lighting grid over the entire space?

    I don't feel at all good about what I see in the two photos but will conceded that without seeing the entire system - and I'm thinking gear box(es), shafting, mounting, blocks, and the controls - this looks like a one of a kind rube goldberg that I have more serious doubts about than from one photo. Maybe there's a counterweight? A 2 hp motor can lift maybe 2000 pounds at 30 fpm, or 4000 at 15 fpm. A normal 40-60 ft lighting batten usually uses a 1 1/2 to 2 hp motor. An entire lighting grid should be substantially heavier.

    This also looks like its been around for a while. Lighting use to weigh a lot less than it does today, and it looks like you have movers and LED - a lot heavier than what was common when this was probably designed.

    I've only once in 35+ years of consulting said "don't let anyone under that rigging". I could imagine if I walks into your space saying that for a second time. Tie it off and get someone in there to assess it properly. I'm sorry I'm not close or I'd stop in because of the nature of the system. I won't name friends or acquaintances, but try to find someone who is a ETCP Certified Rigger. Heres a list (assuming links works after I paste it) to certified riggers in MA http://etcp.esta.org/cert_technicians/searchresults.php?state=MA but Rhode Island might have some also.

    Get approval and find someone in the morning.
     
  10. BillConnerFASTC

    BillConnerFASTC Well-Known Member Premium Member

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    Oh look. While I was looking at maps to see where you were, you found someone. Do it.

    Ethan: Please take some photos and tell us about it!
     
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  11. What Rigger?

    What Rigger? I'm so fly....I Neverland.

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    Excellent move! I too would love to hear or see more. Sounds like more than a few clew plates involved.
     
  12. peacefulone61

    peacefulone61 Active Member

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    I spent yesterday combing through all of the archived documents for the space and at least have been able to figure out when it was installed and by who. I have contacted the company to see what information they have. I also found a bill for a replacement shive that was done about five years ago and have reached out to them to see if they did an inspection at that time as well. I have put in a request for an inspection through the school for budget authorization and plan to take more pictures today
     
  13. AlexDonkle

    AlexDonkle Active Member

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    The arrangement of a single motor splitting off into multiple lift lines locations for the grid sounds very similar to how most center hung scoreboard hoists work, e.g. Peter Albrecht hoists.
     
  14. BillConnerFASTC

    BillConnerFASTC Well-Known Member Premium Member

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    But not usually clewed were they? Separate lines all wound separately on a drum? Putting them all on one lead line to a single clew sure seems the antithesis of design to eliminate single point failure.
     
  15. peacefulone61

    peacefulone61 Active Member

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    So I was able to get more covers out of the way here are additional photos

    I was wrong with my initial view from the ground. it appears there are two lines on the drum that feed the six lines for the individual shives.
     

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  16. BillConnerFASTC

    BillConnerFASTC Well-Known Member Premium Member

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    Too much unknown about design factors, brakes, and control.
     

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