How do you feel about a three way? Two in the same room?Workable solution if you have qualified riggers to marry the two linesets but does not seem like a good design. Longer arbors and/or wider weights perhaps with ladder truss battens seem safer.
I don't think anyone will argue with you about ideal. That being said, it's a lot more likely to get a venue to marry arbors than in is to get them to renovate the fly system.I find marrying counterweight sets to often lead to unsafe rigging. Generally increasing arbor capacity is safer.
Can you marry line sets safely? Yes. But there is a lot involved. You need to do the proper load calculations to ensure that you’re not overloading individual components of each line set. It’s better to try and treat each line set as a separate system, such as hanging fixtures on one line set, and then all the cable on an adjacent line set and only have the pigtails of the fixtures jump the “gap” between them.
I will continue to advocate for doing what is right and best, not for what we can get away with. Hard sciences, athletics, and other disciplines in academia don't give in nearly as easily as the performing arts, and especially theatre. I suspect it's because we are creative in our approaches and uses of materials. Still, I'd urge everyone to ask for great facilities and systems and equipment and materials, and not be so eager to settle for last place support.
Bill,To me it means a second arbor - often shorter than the prime arbor - installed in guide system just under and connected to prime arbor, with handline retied - so in effect a longer arbor. Usually for electrics, no travel or trim or loading issues. For tall items, like a heavy wall (personal experience), you may have to cut and retrim lift lines, or pick up from bottom of piece.
Bill,
Agreed. But we should caution our audience that these stunts are performed on closed roads with professional drivers.
Adding the trailer arbor is a good solution BUT, if you are going to consider it, be sure and go back to the manufacturer of the head block and find out what load they designed for it. If the set has a 1,400 LB capacity arbor and the HB was engineered for, say 1,800 LB, you don't have a lot of room. Exceeding the design load is not recommended. You should also investigate the loft blocks. And be conscious of where you apply the weight on the battens. Keep in mind that older systems, +15 years, may not have as robust a design factor as most manufactures have now. Typically, the manufacturers I deal with now want to know what the capacities are before they quote. One 2,400 LB set will be a special if all the rest are 1,600.
If the blocks have a manufacturing sticker on them, you should be able to go back to the builder with a job name and approximate date to request the information.
Follow the load path from one end to the other and be sure that your safety factors are accounted for at every part. Be more sure of the actual loads, not a guestimate.
Ted
That must have been rather...uh...exciting.
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