TSM Project 2008 - Raked Revolve

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FIRST IDEAS.

I have only seen a few plays and two musicals in my whole life, so the ideas ill be coming up with are just going to be completly from my imagination. With this disadvantage I have still been able to come up with a few ideas and a final project that I want to do.

The first thing I wanted to try and create in the Ath was a flying person for the performance "Peter Pan". Not just one that flies from one side of the stage to the other, but when the actor actually flies out to the audience and is able to control the height they are flying at themselves. The health and safety issues and risk assesments would in my eyes be alot of trouble when it is just easier to make the person fly across the stage. The main pieces of equipment needed for this would be a channel track, hanging clamps, 1/8" aircraft cable, 1" rope, a special head block, tram and traveling blocks, a floating block, aircraft cable, a cable end stop, 3/8" cord, a floor pulley, a live-end pulley and a dead-end pulley. I was really wanting to do this but felt that other peoples ideas were a bit more challenging, so I decided to keep my options open and keep thinking about things.

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I then thought of "The Wizard Of Oz" and its yellow brick road. For this I was thinking of having a spiral staircase going from centre stage round to one of the fly floors a that also dissapeared when the actors would walk up it. For this the staircase would have been built with metal and no welding atal. The main equipment i would have needed here would be a pipe coupling, washers, newel post section of PVC, 3/4" plywood tread, 3/4" pipe bluster, 2" pipe nd 2 1/2" PVC column, 3/4" plywood bracket and a pipe flange. To help with the stairs actually disappearing with the actor I would use something similar to a chain hoist. However, I felt like this idea was far too complex for me and quite a few other people are wanting to do their projects using staircases.

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Finally I was in one of my Lighting Design classes and my teacher mentioned something about a revolve stage. After that, I soon realised what my project was going to be. Enjoy the making of a revolve on a raked stage.

PROJECT INTRODUCTION.

My final decision is to create a revolve on a raked stage. First of all I want the revolve to be sitting flush with the raked stage. There are several ways to make a revolve work. You can hace a cable-driven revolve, it can be gear driven ( like Peter Strains(graduate 08s)spining disc.), a wheel-less revolve (using pivots), a frame-less revolve and finally theres a spring-driven revolve. The raked stage is going to be odd-shaped just to make things a little more complex. I will make a list of the pros and cons of the revolve. Then I am going look at how to build the revolve seperatly from the raked stage after which I will make adjustments to fit the two together if needed to.


PROS AND CONS OF THE REVOLVE AND RAKED STAGE.

RAKED STAGE

When making this raked stage, I'll have to make the angle of it rather small as there will be a person standing on the revolve as it is moving. It will be moving at a fairly fast speed and I do not really want to have the actor come flying off it at high speed. So the stage will have only a small angle.

REVOLVE

The frameless revolve would be built by cutting segements of ply and putting them together with overlaps and small pivot points. If I have chosen to use the frameless revolve the pros and cons would be as follow:

PRO'S:

    • The design offers several advantages over framed and laminated plywood revolves.
    • The segement developed should minimize waste of plywood.
    • The revolve can be easily taken apart and put into storage and be taken out to put on stage again as many times as needed.
    • The revolve needs no framing and only an ordinary bolt basically to work.

CON'S:

    • Roughly 26 sheets of plywood would be used to make it
    • Really need to think about the overlap, if its too small it may make the revolve rather stiff to work.
    • Have to really look through caster types as rehersals are taking place they may get rattely easily, so try and get heavier duty casters than load analysis might suggest.

The wheel-less revolve would be built by creating semi-circles glued together to create several layers and a full circle revolve, id also need a certain perimeter ring of oil filled ultra high molecular weight to mount to the bottom of the revolve add pivots etc to make it work.

PRO'S:

    • This revolve has been used before and has said to have run 15 revolutions per performance for 40 performances plus tech rehersals,the revolve hows no sign of wear and the UHMW still had traces of oil.

CON'S

    • If I was to do this, the revolve would be sitting slightly higher than the stage, there fore a small ramp would also have to be made to hide the front of the revolve.
    • With the chain motor id be using the revolve would take roughly about 10seconds to make half a turn - which is a long time. I want it to be quick.
    • Also, the chain of the the motor will be running from the revolve upstage to the backwall,so it would be seen if not coverd by the back wall, so I dont think it'd look too good.

Theres also a gear driven revolve that Peter Strain (graduate 08) had made. I dont feel that this would work as it would be horizontal and alot of strain on the area where the actor would be standing. I feel as though it would struggle to make that revolve. There is also a way where you make the bottom of the revolve completly covered in casters. This method can be extremely noisy as any dirt or debri on the floor will make a much louder noise than expected. If I was to create a cable driven revolve all the machinary needed will in the end be quite expensive. For this revolve I would need an idling drum, driving drum, worm gear, variable speed drive, 5 H.P motor, cable to stage drum, take-up, channel drum,tracks for slip stage, thrust wheels and an emergancy manual turnstile. This is a good way, but in my opinion a very expensive way to make the revolve when I can find a much simpler way. The final method I thought of and came across was a spring driven revolve. I have chosen this to be my way of building my revolve. I will go into the pros and cons of this method in the next areas.

MAKING THE REVOLVE.

The overall size of the revolve is not going to be massive as it is only to be a bit wider than the actor that will be standing on it,plus if the revolve was huge it would put more strain on the device etc. The diameter of the revolve will be 6 foot. There will need to be two seperate revolves made, one for the person to be standing on and the other for casters to be put on so the revolve runs smoothly.

For the top revolve, plywood can be marked with a trammel bar on a 3foot radius. The revolve can then be cut, and the wastage can possibly used to fill gaps in the floor once the revolve is complete. At halfway point and to either side of this revolve, two small sections/wedges sould be cut into it so the back wall can be screwd/bolted into place and be unnoticable on both sides as they will both be seen by the audience.

The second revolve will have to be made slightly bigger to be supportive and stable. For this one, two sheets of plywood can be butted edge to edge and marked again with a tramel bar but this time on a rdius of 4 foot. The two halves can then be cut out again saving the craps just incase. Six radiating spokes will need to be made and placed evenly on the top of this revolve (hopefully youll understand why later on). These can be used as mounting plates for rubber-tired castors; two of them should be used to form a batten to screw the two halves of the revolve together. The spokes should not meet in the centre, this should be done so that there is a square trap that can be used as a mount for the pivoting axle. Between each spoke, it would be adviseable to cut sections of x amount, these together with the end of each spoke should form a circular sweep that is solidly screwed to the top of the revolve and form a more stable and stronger structure.

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There should be two suppllementary castors mounted near the centre to prevent any strain from the butt joint holding the two halves of the revolve together. The castors should be placed with their wheels at right angles to aline representing radius. All castors should be rigid or locked swivel castors.

THE SPRING MOTOR

For this to work a certain type of spring will have to be used. One that is strong and able to do its job. After thorough research I found that a spring called "torsion-spring" seemed ideal. Self obtained and lightweight, torsion springs start unwinding at full torque and loose effectiveness as they unwind. Bearing this in mind, it will give the revolve the sudden start and the controllable deceleration it needs. To help with the start and stop points a cam like version of the notched discs used on locking-swivel casters would have to be made. Torsion springs are made from various wire sizes, come wound as right or left hand coils that are available in a number of different inside diameters.

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After gathering information from a table supplied by the Bloomington (Minnesota) Door Company and from someone I know, I figured out that a 2 1/4" I.D. x 0.250" wire size garage-door spring would be pretty good for the job. These springs come with two mounting cones designed to sleeve over the shaft they turn. One cone bolts to the supporting structure and the other grips the shaft usually by means of a pair of set screws.

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With help from my friend and other information, we came to an estimate that a spring as short as 2 1/2" would trun the revolve through 180degrees at speed. But torsion springs only last so many cycles before breaking, and the longer the springs are, the longer they last. Besides I wanted more speed options than that spring is capable of. Wedging screwdrivers between the coils to spread them far enough apart to aroound 5", that length should allow roughly a full turn and a half.

THE NOTCHED-CAM STOP

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The image above should and hopefully show clearly, the revolve and parts of the notched cam stop that can be made from a double layer of 3/4" plywood. The notches are designed to catch the end of a 2x4 drawbar, hinge-mounted on the springs baseplate. A bungee cord between the baseplaet and the middle of the 2x4 should pull the drawbar toward the centre of the cam. The plywood should be bolted to one of the two attatchment plates to sleeve over the revolves shaft. The second attatchment plate bolted to the revolve to the top of the shaft. If this would be put to the test, surely the two set-screws in the attatchment plates shaft collars wont keep the cam or the revolve from spinning on the shaft?????so I would say that welding the attachment plates directly to the shaft would be a more strong and longer lasting method?

Once the revolve has been built and the stage has been made with gap in right place for the revolve to be going, the pivot of the revolve will be at the angle of the rake, which is not steep, then screwd down and the spacing area will be coverd by the excess material used.

THE OPERATION

Stage crew will have to wind the spring before each show by spinning the revolve backwards. When the notched cam has reached its preset, the bungee cord return should pull the 2x4 drawbar into the cams notch, which should lock it in place. As soon as the stage crew trips the drawbar, the bungee cord should pull the drawbar back into positon to catch the next notch and another stage crew member should help brake the revolve so it does not stop with a jolt type thing.


ROUGH COSTINGS

The 2 1/4" spring + two mounting cones = £50.00

The 1" shaft collars = £02.00 (each)

The 1" flange blocks = £25.00 (each)

Ply wood (£7.00 x 6sheets) = £42.00

Rough Estamated Total = £150.00



DATA FOR A 2 1/4" X 0.25" TORSION SPRING

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