Spinning Flat for The Producers

[Bix]

Here is a fun little project I have coming down the pike for The Producers. The designer has called for a circular flat to fly in and then spin around. The flat is essentially an inverted revolve with a swastika on the front of it (see attached drawing from the designer).

Here is my question to all of you. How would you drive this spinner and why that method?
· Cable/Chain drive around the circumference?
· Friction drive around the outer edge?
· Shaft at pivot with roller chain sprocket?
· Find a stagehand that has been on “Wheel of Fortune”?

Consider the following:
· The materials for the circular flat will weigh around 280 lbs.
· The flat will need to spin at around 10 rpm with speed being adjustable.
· The motors I have available are; ¾ HP with a 10:1 reducer, 2 hp with 20:1 reducer and a 5 hp with a 20:1 reducer.
· Although the designer specified direction of rotation, we all know that as soon as it hits the stage the Director will want it to spin in the opposite direction. Would this change which method you would choose?
· For ease of discussion let’s assume we have a solid structural plan for the rotation and a control system for whatever method you might choose.

 

[tayklor]

While I don't do much scenic work at all, I'm going to take a stab at it. I have no idea how safe this might be, or what the 'right' way of doing this is.

Start with a flat. This is the backing and main structure. This is also what will be attached to the line set. It will house the electrics for the motor, too. I would anchor the rotating piece to the center of the flat with free-rotating hardware. The rotating piece would be driven with an outer-circumference cable. The size of the motor would have a lot to do with the size of the thing. I have no idea how this is determined. Are these AC or DC motors? If they were DC, I'd use some sort of autotransformer and rectifier to allow for speed control. To change directions, reverse the polarity of the connection to the motor.

Again, I kind of have no idea what I'm talking about. I'm more of a lighting and sound person. I'll be following this closely...

 

[65535]

Need a lot more info on the motors.

I would spec a 3PH or a DC motor because you want to be able to adjust speed and direction. Depending on your motor (1725/1800 and 3450/3600 being common) and reduction available you'll want to target your maximum RPM to match the desired speed of rotation of the piece.

The easiest way would be to couple the motor to the shaft that the piece rides on, probably using pillow blocks and pulleys.

This isn't a simple quick endeavor and unless you have 3PH or DC motors available pretty much impossible.

 

[esmphoto]

I would probably use a stage hand because that means pretty much 100% adjust-ability of speed and direction without costing anything.

if not that then probably friction drive on the outer edge because this would be the easiest to install and engineer.

 

[Teber]

This may be an odd way of doing it, but i would make it a separate piece on the flat with a bolt and a washer through the flat, hook up a drill once it touches the stage floor and have a crew member operate the drill. It's an odd way and I hope it answers the question

 

[David Ashton]

forget all that structure, fly in a rear projection screen and use a rotating gobo or video projector, you also wouldn't be left with a big useless lump of hardware.

 

[Bix]

Here is an update. The director and designer informed me that they will need a stagehand back behind the flat anyway for other business. Simple is better, so we will operate it with a stagehand.

If that was not going to work, I would have went with a friction drive around the outer edge using a 5" wheel and a 3/4HP motor (mainly because that is what I have available.) The 5" wheel gives me the appropriate RPM on the flat and the 3/4 hp motor is plenty big to handle the torque.

 

[sww1235]

I would have done it with the friction drive, except drive it inside the rotating bit, so the wheel would not be seen

 

[dancarden]

I would probably use a stage hand because that means pretty much 100% adjust-ability of speed and direction without costing anything.

if not that then probably friction drive on the outer edge because this would be the easiest to install and engineer.

since when did a stage hand cost nothing?

 

[chausman]

since when did a stage hand cost nothing?

When you've given him something to do other than eat free doughnuts.