Industrial Motion Control Finds Its Way To The Skylight Opera Stage
Industrial Motion Control Finds Its Way To The Skylight Opera Stage
January 31, 2007:
The Skylight has never built two spinners in one set before, let alone one that had to move 2500lbs of scenery and stop less than an inch away from the other with 1500lbs rotating in the opposite direction. And, do this 12 times a night. Spinners are the turntables that allow multiple sets from different parts of the show to use the same space on the stage. By using hardware donated by Rockwell Automation and Baldor Electric hardware donated by NOVA Systems Inc., along with mechanical drive trains built by The Skylight and the time and expertise of Kenn Anderson of NOVA in particular, they are literally able to move houses. The seemingly effortless motion and accurate repeatability allow the singers to focus on their performance, and the reliability of the system means the crew can focus on running the show.
The set includes two moving decks above the stage floor that interlock for placement of the stairs, which the actors need to use. The smaller one is the Stair Spinner and the larger one is the Big Spinner with the higher deck. There are a total of over 80 casters used for both spinners to allow them to move easily and quietly. The each deck rotates around a pivot, which passes through the floor of the stage into the Trap Room below the stage. The pivots were located by precise measurements and before the decks were set in place onto the spinners and their relationship checked.
The Stair Spinner and the Big Spinner not only are going in different directions, but need to have synchronized motion because both decks are irregularly shaped, not round. The Stair Spinner has to move out of the way and wait for the Big Spinner to complete its move before it can move back to where it’s supposed to be.
The drive mechanism of the Stair Spinner is unique and designed by The Skylight staff specifically for “Tartuffe”. All of the assemblies and mounting brackets were built in The Skylight Scene Shop. The unit is designed to execute a 180 degree rotation in under 20 seconds.
The mechanism of the Stair Spinner is driven by a servo motor mounted to the ceiling of the Trap Room. The drive shaft extends up through the floor and has a large sprocket mounted to it. The spinner has a large steel disk underneath it with an industrial version of a bicycle chain attached to it. When the sprocket on the motor spins, it drives the chain, spinning the platform, much the same way pedaling a bike spins the large back wheel. A gearbox is used to reduce speed and increase torque.
For the Big Spinner, two gear boxes are used, with one being a right angle gearbox. Two drive shafts that counter-rotate make the unit spin. Universal joints allow the twin shafts to angle down to two 8” wide by 18” high, non-marking forklift tires, which drive the unit in a circle. The upper deck on the Big Spinner had to be constructed to support up to five actors when the unit was rotating at top speed. The framing is similar to that used in residential construction, but has to be more robust since most houses do not spin 12 times a night.
The industrial servo system for the Stair Spinner was donated for “Tartuffe” by Rockwell Automation. The servo system for the Big Spinner was donated for “Chicago” by Rockwell in 2002, and has been used in 10 of the last 25 productions. The synchronized motion for both spinners is done with a Baldor Mint Drive (motion controller) which was donated by NOVA Systems. The industrial control panel which houses all this equipment was constructed in NOVA’s panel shop. In large part, the assistance and generosity of Rockwell Automation and NOVA Systems Inc. is what made the spinning spectacle of Tartuffe possible.