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pivoting track system????


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im trying to work out a problem with a track system. I am trying to move a sofa from left to right (possibly on a track) however the sofe must also be able to pivot 360 degrees and all must be operated from an unseen location. does anybody know if there is a simple way of doing this? if so any links or diagrams or suggestions will be very welcome. thanks!

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Does the sofa need to be able to pivot freely or does it need to be built into the track way so that it pivots and moves at set times? (If that makes sense!)


The latter makes things more difficult and therefore more costly!





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I'm a bit confused by the recommendation of Foys and unusual. Unless I have read this wrong, the OP wishes the sofa to track along the floor, and be able to rotate on a pivot through 360 degrees in a horizontal plane, as in spinning on its castors. I don't think it needs to fly in and tumble - does it?
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I interpreted the O/P the same as Paulears.


It is identical to the movement that was required of the Pool Table in Frantic Assembly's version of Othello.


They used a truck with a pin protruding out of the middle bottom which went into the stage.



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Does the sofa need to be able to pivot freely or does it need to be built into the track way so that it pivots and moves at set times? (If that makes sense!)


The latter makes things more difficult and therefore more costly!


Seconded! Does the sofa need to be able to move when there are people on it? Is there any chance of putting a stage hand behind it? Most importantly what's your budget?


Unfortunately any sort of drive system that's located off the stage is going to necessitate cables (electrical or mechanical) running to the sofa. If you can handle that from a safety point of view (think trip hazard) then you can probably do it fairly cheap. If not you're stuck with either a false stage floor with recessed drive system or motorising the sofa. Neither of which are cheap.


If you can pull it off I'd seriously look at putting the thing on castors and getting a stage hand to crawl along behind it and spin it around.

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The cheapest way to do this is with castors and a stage hand. Remember that there will always be one side of the sofa that's facing away from the audience!


If it really does need to be controlled from off-stage either due to excessive speed of movement or the design of the sofa itself, then you are looking at some form of track system.

(I would avoid free-running motorised setpieces. They can be seriously dangerous!)


At its most basic, a track system uses one or more grooves in the floor and some suitable rope (usually steel wire) that runs in the grooves.

The shape of the grooves depends on the system in use - inverted-T is common as it's easiest to make, but other shapes can be used.

You'll usually have some operating towers in one or both wings, which are used to tension the rope and either provide a vertical section of rope for the operator to pull, or contain the motorised drive system.

They should also have brakes!


If the towers are in both wings, the rope runs between the towers and has weights both ends to tension. These will rise and fall depending on where the setpiece is onstage.


If you only want the tower in one wing, then you'll need to arrange a pulley in the other wing or onstage. This takes up much less space as you can bury the pulley in another setpiece or the false floor. In this case, the rope runs from the tower, across the stage, around the pulley and back to the same tower. Again, weights are used to maintain tension.


The height of the towers is key - you will probably need a pulley system to get the onstage travel you need given the acceptable height of the towers.


The movable scenery has one or more "Pins" that fit into the grooves and engage with the rope. This connection is key, and varies dependant on purpose.

- These are not just sticks. The pins need to be specially shaped and have running bearings suitable for the groove design.


For your requirements, you'd need at least two grooves, although it's easier with three:


The sofa is bolted to the top half of a turntable.

This turntable has a centre pin that goes into Groove 1 and attaches to Motion Rope.

Optionally, the lower (static) half of the turntable has an edge pin that drops into Groove 3. This is to stop the static drum rotating, and doesn't need a rope.


Groove 2 is special, and contains the Rotation Rope.

The rope pops up out of the groove, goes around the rotating half of the turntable and then drops back into the groove. You'll need a simple pulley system to do this.


(It can be done with one groove, but that's considerably more complicated.)


With two grooves, you don't have a static drum and you mount the rotating drum on castors. It's harder to keep the 'spin' pulleys in the groove this way though!


To operate this:

a) Pulling on both ropes simultaneously at the same speed and direction moves the sofa across the stage without rotation.

b) Pulling on the Motion Rope while the Rotation is braked will cause the sofa to spin gently and move across the stage.

c) Pulling on the Rotation Rope while the Motion is braked will cause the sofa to spin on the spot.


You can do any combination of moves by using different timings and speeds of pull.


However, all this requires a seriously good chippy to put together. A reliable system takes precision engineering.

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