I am having 2 small line arrays installed soon. The contractor is concerned about the arrays rotating as the hoists go up. I recall seeing audio riggers tying a line back to the hoist to prevent rotation but since i was not on the audio crew at the time, I don't recall what the actual method was.
Does anyone know of a method that would prevent rotation, without having to anchor to a nearby structure?
Got a picture? The hoist has to hang on something. Generally to prevent swing you just tie off to that. Like was mentioned it will twist going up but it will eventually straighten itself out.
Amiers
Unfortunately I do not have photos. The install has not started yet. The mount point will not be accessible after install so I was hoping to find a solution that does not entail tying off to that if possible.
Coldnorth57
That was my thought as well, but my contractor (who should have more experience at this than me) expressed concern. The given solution is to run a tie to an eye-bolt on the wall behind the array. This would entail needing a pole to reach up and unhook it whenever we need to lower the array.
I'm not opposed to this solution, but if i can come up with a solution that doesn't have to be disconnected prior to lowering, that would be better.
If I can't hang a focus point above to keep an array steady, I generally tie off two pieces of tie-line to the bottom of the array and fly it out. I can use the bottom two pieces of tie-line to steer the array, and then get up and clip them once it has been focused. That way you don't need to untie anything once it is flown in.
Two motors per array is the obvious solution to the rotation. Or use a single fixed winch with 4 lines, located in a place you can inspect it, and save a lot of labor and work over the life of the systems.
You may want to question who is installing this for you if they can sell you the line arrays but don't know how to keep them from spinning.
If this is a permanent install, my preference is for a Zbeam and a spine frame adapter on each array. The Zbeam gives you the pan control down to granular precision, and the spine frame adapter interfaces the Zbeam with the array frame your line array hangs from. By wrenching forward/backward the spine frame adapter, you control the location of the pick to adjust the tilt of the array.
Install goes something like this:
Install the points.
Hang the motors.
Assemble the array, mount the rigging frame to the top.
Add the spine frame adapter and Zbeam to the rigging frame.
Raise the cluster so it is fully supported from the single-point motor and splay the cabinets.
Adjust the spine frame adapter to get the x.x° of tilt you need.
Verify coverage & clearances once more and adjust spine frame adapter as necessary if you need to correct for any tilt-adjustment from removing the motor.
Mark Zbeam and Spine Frame Adapter positions on top with a grease pencil when the tilt/pan are finalized, so next time you need to service the cluster for any reason you don't have to painstakingly refocus it.
Dress cables and clean up.
You can opt to leave the motors in place and use the extra points on the Zbeam just as safeties but in permanent installs usually the motors are pulled down immediately and the arrays hang off of the stingers for some number of years before anyone needs to get to them again.
View from Step 6.
View from Step 8.
Goes without saying but this is not the way the weekend warriors or road guys do it. This is how you do it if you want to hang your arrays cleanly and precisely with reliable focus so your boxes aren't wasted spraying over walls or the stage where you didn't want them to spray.
