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Cable management with chain motors

Discussion in 'Lighting and Electrics' started by Aaron S., Aug 14, 2017.

  1. Aaron S.

    Aaron S. Member

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    I have been looking for a way to manage my cable runs a little more efficiently. My theater uses truss on chain motors for our electrics. No raceway or anything. The location of the electrics change every show, so we can't just drop cable and leave it. We drop our cable onto the truss and run it off stage to the rack. We normally hang a few pulleys to pick up the slack when the truss goes up. This normally works fine, but when we need to fly in an electric in to work on it, we have to fly in a few cable picks.

    I'm trying to see if there is any solution that lets me fly the truss in and out while picking up the slack on the electric. I have seen from Sapsis what they call "chain runners". This is sort of what I'm thinking of, but I have a few issues.

    1) When the electric is at it's highest trim there is only about 10" of clearance between Hook and Motor.
    2) My cable obviously can't hang in the way of lighting fixtures. Which means a distance of about 2'6" from chain runner to the bottom of the cable loop.
    3) If I have 4 multi runs on an electric, and I have 5 loops to pull the swag up, I now have a bundle of 25 multi's hanging off the electric.

    If I think about it more I could probably come up with a couple other concerns, but I think this will get the conversation started.

    Trying to see if there are any other suggestions or options that I can look take a look at.

    Thanks for any suggestions.
    Aaron S.
     
  2. BillConnerFASTC

    BillConnerFASTC Well-Known Member

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    There are many cable managment designs. Where are the feeeders coming from, or specifically, is there a walk on grid overhead or feeding from wall?
     
  3. Aaron S.

    Aaron S. Member

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    No grid access above the electrics. Coming out of the wall directly off stage of the electrics, about 15' as the crow flies.
     
  4. BillConnerFASTC

    BillConnerFASTC Well-Known Member

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    When you say high trim, i guess you mean play trim. About how much travel to low trim?

    Nothing simpler than a tub or pan sitting on the truss. Feeder piles in tub as you fly.
     
    Last edited: Aug 15, 2017
  5. porkchop

    porkchop Well-Known Member

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    Depending on the infrastructure you have in place the easiest thing to do might be buy a CM prostar or two and use them as motorized cable picks. They aren't exactly cheap, but depending on how much labor is required for other methods they might pay for themselves in a pretty reasonable amount of time.

    Another simple solution that comes to ming is to have the cable run through large pulleys and let gravity to the work for you on the rack end. If coiled well at the rack the cable will pull nicely out of the coil when the truss comes in and when the truss goes back out gravity (and/or a little human encouragement) will take up the slack and you just coil it nicely again and be done with it. The loose cable by the rack could even be tied off if there is fear that slack will fall through the pulleys inadvertently.
     
    RonHebbard likes this.
  6. BillConnerFASTC

    BillConnerFASTC Well-Known Member

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    Just trying to picture but is part of the problem that the travel and space above the truss do not allow enough space for a single pick and the swag or loop to stay clear above the truss?

    Cable cradles and floating sandbags is an option. Double purchase the first cradle. Ive even triple purchased a cradle. How big is the feeder? Several mults per truss?
     
    Last edited: Aug 15, 2017
  7. Aaron S.

    Aaron S. Member

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    Our electrics get trimmed anywhere from 15'-22' depending on the show. The lowest point we would want to bring them in would be a working height of about 4'.

    How would the cable be ushered into the tub properly? Also, do you think this would cause the truss to roll one way or another at all?

    I do like the tub idea. Thanks for the idea.
     
  8. Aaron S.

    Aaron S. Member

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    We currently have a few swags running from the end of the truss to the racks. The main issue is once we get a set in and masking we can't always bring in the cable swags to allow the truss to come in so we have to work in the air from a ladder or lift. And yes, there is normally 4 or 5 mults per truss.

    I was going to say yes, there isn't space above the electric, but I might be able to rig something up. We have a steel I-beam grid that we hang the chain hoists from, so from the electric to the I-beam is usually about 3', but I might be able to get higher and have the cable run it's own path, not along the chain.
     
  9. Aaron S.

    Aaron S. Member

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    I have thought about the CM solution, but I think the cost is just too far out of reach. Also, once the set is in, that pick might not be able to fly in anyhow. My thought of having the cable run up the chain picking the electric means if the truss is clear to fly in, we can bring it in and out even with the set in.
     
  10. BillConnerFASTC

    BillConnerFASTC Well-Known Member

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    Now I know that your heights are limited and you want to drop it in between side masking - conceptually no different than inside a box set or orchestra shell - that does limit it some. I'm not sure if the weight in the tub would tip the trusses or not. Depends on how truss is rigged. Longer bridles maybe? Last one I did with tubs I got the tubs - from TSC - tractor supply company. I think these: https://www.tractorsupply.com/tsc/product/fortex-round-feeder-15-gal-capacity-black Very thick black rubber like. And then that link kept leading me to others, like a rubbermade oval 100 gal tank but this seemed interesting: Tuff Stuff Products Heavy Duty Oval Tank, 40 gal.

    I did spend time "training" the mults to coil into the tank. The problem is they can hang up on the edge of the tub. I ended up fabricating a hula hoop like ring clipped to lift lines above the piece and that solved it 100%.

    One idea I've not done but have heard some others have tired and it worked - a series of brackets - like a U or Y shaped piece - in this case atop the truss - and the feeders lay in them as it goes up. It does pull the pipe or truss to one side of stage UNLESS you divide your feeders from left and right. Not sure this would work for you - that the anchor point would be high enough.

    You can try the pulley but my one experience was it eventually shredded the insulation. 12/18 would probably require an 18-24" wheel - consider bicycle rims. You could of course go to the flat cable like ETC uses on thier prodigy E series and rollers - but that is expensive.

    Last, look at Igus products - their twister series. These guys have shown up at LDI and are eager to get into theatre. (I think the "live pipe" may use this.) http://www.igus.com/wpck/17659/twisterband_HD Looks expensive but it is just a very clever plastic casting that clips together so I suspect not as expensive as it looks.
     
  11. rochem

    rochem Well-Known Member

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    One tried and true method is to run a rope through one or two loft blocks on the ceiling, tie your cable to one end of the rope with an appropriate amount of swag, then weight the other end of the rope with sandbags until the line is just barely sandbag-heavy (cable wants to go up). As you fly in the electric, the cable will descend with it but always remain fairly taught above the truss, thus staying out of the way. Since the set is bag-heavy, the cable pick will always stay a fixed distance above the truss, unless of course you run out of trim height in which case it'll simply stop. This will work automatically without any human intervention required, but since the set is pretty close to evenly weighted you can also tie it off or manually move it if you have a reason to do so.
     

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