With moving cable management systems, such as the e-spool and zig-zag, complicated stage applications can be implemented even in confined spaces and with high loads. In this article, Justin Leonard, the-chain director at igus, explains how...
The challenge for every stage builder is to set the perfect stage. Every job is different, because stages are not off-the-shelf. Each one is unique, which means that each and every component not only has to be strong, reliable and efficient but must also fit together perfectly. There are also many other technical requirements; these include carrying high loads, such as those found in sound and lighting systems, stage sets or entire stage platforms, and also quiet and safe operation.
Whether for vertical, horizontal or rotary movement, much has taken place in the theatre since the ancient times. Back then, the ‘deus ex machina’ – a term was coined from the conventions of Greek tragedy, where a machine was used to bring actors playing gods onto the stage – was still moved by hand using winches and pulleys and pure physical strength.
Today, human power has been replaced largely by motors and cables. However, things that have not changed are the basic challenges of dynamic applications. The systems themselves must operate quietly and out of sight, so not to interfere with the performance. However, there is usually only a small amount of space available. At the same time, stage technicians and engineers need systems that are easy to assemble, require little maintenance, and promise maximum service life. Otherwise the curtain may fall at the most inopportune moment.
Traditionally, cable reelers are used for these applications; they are reliable and have served the industry very well but do have their limitations. And these are becoming more and more obvious as we enter this multimedia age with high speed data and digital services. In the heart of the cable reeler is a slip ring, which has its limitations. These limitations have to do with reliability due to the effects of corrosion or debris getting into the system, which is generally not a common problem in the theatre or studio but it can become an issue for outdoor venues. The biggest issue is when trying to move different bus systems and power systems together. Under these circumstances, it becomes quite complicated; either requiring separate reelers or a composite cable, which will invariably be very expensive and nearly always be of a bespoke design.
Understanding the special requirements in stage technology, igus developed an operationally reliable alternative that is suitable for noise-sensitive applications. The e-spool system is extremely compact and is able to guide a large number of different energy, data, control or pneumatic cables together in very confined spaces. In terms of design, this is a combination of two proven igus product families, long-lasting e-chains and the flexible twisterband, which connects the spool to the shaft end block and forms the interface between fixed and moving cables. In this way, it allows continuous cable guidance during rotational movements without needing a restrictive slip ring.
Upper and lower stage machinery
Usually, two locations are defined in stage technology: upper and lower machinery. Here, e-spool is suitable for both because it operates so quietly. In-house tests show that with an appropriately equipped e-spool, the noise level could be below 46 dB (A). Such a system is used in the upper machinery in Mountford Hall, one of the largest concert halls in Liverpool. Here four e-spools are used to supply power and signals for the adjustable loudspeaker system, which can be set so that the best possible sound balance is always achieved during different events. At the Culture and Congress Centre in Torun in Poland, a total of ten e-spools are moving the power cables for the lighting trusses. Further afield in Australia, the Sydney Opera House also uses e-spool for its upper machinery. For lower machinery installations, a total of 18 e-spools are used at the Cologne Opera House in the stage pit to ensure the necessary energy supply for stage floor operations.
Wherever stages or heavy stage platforms have to be moved, lifting heights of many metres and heavy loads have to be managed. So far, systems that have been used are noisy, space-consuming and visually intrusive. With the zig-zag installation, there is an effective alternative for this. By reversing links at certain points, igus energy-chains can be stored in a zig-zag pattern which requires little space. When the stage or platform is raised, the e-chain unfolds quietly. When lowered, the zig-zag installation practically disappears as it is stored automatically in a basket, which can be integrated in the stage pit or fixed on movable lighting trusses. At Mountford Hall and the Wielki Theatre in Warsaw, they supply the lighting trusses with energy. At maximum height, the system is fully retracted in its basket directly above the respective crossbeam – the system unfolds automatically when lowered. For similar, more compact installations, liftband offers an alternative system for shorter vertical heights.
Studio camera robots
For camera robots and guidance systems plastic energy supply systems are a cost-effective alternative to the conventional materials used. An example of where they are used is in the ARD-aktuell (ARD current news) studio, where, among other things, the Tagessschau (daily news) and the Tagesthemen (daily prime time news) are produced. The former independent specialist for studio technology, Camerarobot Systems GmbH, which is now part of Mark Roberts Motion Control, was looking for a reliable guidance system for its three camera robots. Not only did it need to have a long service life, even at high loads, it also had to operate very quietly. The E6 modular system, which can be adjusted for the different travels, has chain links with abrasion-resistant connections, which ensure extremely low-noise and low-vibration operation. A more compact alternative is the micro flizz, which is suitable for fast tracking shots in very tight spaces.
As a competent partner that understands the specific problems of stage technology, igus offers a wide range of modular cable management systems that can adapt to any stage application. For more information, please visit: www.igus.co.uk/theatre