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Need Help with Turntable, Revolve, Rotating Stage...

Discussion in 'Scenery, Props, and Rigging' started by draco17315, Feb 7, 2009.

  1. draco17315

    draco17315 Member

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    Hello all, and thanks for any help.......ok, here's the scoop. We are building a revolve for use in two shows, Annie and Les Mis...I know...using a motor is rough, but we have the equipment and all that, we have the safety under control, we have an engineering student helping as well.....here is what we need help with, a little info first, it is a 22' diameter, we have used the 'cheese' method that so many people have recomended, we built it on a strong, steel pivot point that is lubed up and the casters are at all the preassure points, upside down attached to "arms" that radiate out from the central pivot point. They are rigid casters and are on the correct angles. manually, the stage seems to spin fine. we then ran a (sorry forget the name) schedule 40 chain (like a motorcycle chain) around the groove made by the wedges around the outside of the turntable then the chain exits through two tension gears that streighten out the chain that then runs back to the sprocket on the 3/4 HP motor we have. We have a nice speed control box, all that works fine except:

    1) I think and from all the reading I found that the motor should be pulled back so that all the slack is out of the chain and then the motor should be mounted in a fashion as to not move. I dumb it down for myself like this.....remember when you were a kid and rode your bike everywhere.....it never failed, sometimes your chain would pop off...the solution...turn your bike upside down, loosen the wheel bolt, attach your chain to the fron and back sprocket on the bike, pull the tire back until the chain was tight and then tighten the bolt back down.....isnt this the same principle just on a much larger scale??? however my assistant who is an engineering student (and very smart.....) thinks we need to mount the motor to a "cart that rolls slightly forward and backwards and then use springs pulling back on the motor cart to keep the tension tight but allow the motor to still "adjust" itself as the turntable spins allowing the motor to "self correct" to compensate for any human error in cutting the turntable itself...would this really be necesarry????....we tried this to no avail, the chain kept popping off and the time that it did not pop off, the chain did not have enough friction to spin the turntable, it just rubbed arround and spun freely without spinning the turntable which brings me to problem #2.....

    2) What can we do to get the chain to "grab" the turntable and get a constant rotation without the chain slipping?

    3) we want to increase the safety with an e-stop....I am told mushroom e-stops are the best way to go...can anyone send me a schematic to add these into the wiring and where can I get them....also, does a common household light switch provide the same oporation as an e-stop or deadmans switch?

    I think that is the most of the problems for now....I do best with diagrams, very visual, but any and all help is appreciated........thanks for all help

    Joe
    Technical Director
    Susquehannock High School Theatre
    Glen Rock, PA
     
  2. icewolf08

    icewolf08 CBMod CB Mods

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    Occupation:
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    First of all, welcome to CB. Hopefully we can help you a little.

    I am no automation expert, but I have a feeling that your 3/4 HP is way underpowered for driving a 22' revolve, especially if you plan to move it with anything on it. When we drive a revolve of that size we run 2x 5HP motors. As for your chain, you do need tension, but you probably also need something for the chain to grip on the edge of the revolve. Possibly the simpler solution is to do a direct friction drive, put a tire on the motor and press that against the edge of the revolve.

    While it is all well and good to try and build your own system I would recommend contacting a professional. You really will want better control and safety than any home brew system can give you. As when most questions of this nature come up I would suggest contacting Creative Conners, Inc. . They specialize in automation for everyone. They can rent you the gear you need to do your effect and also they can provide consulting on how to build your system.
     
  3. DaveySimps

    DaveySimps CBMod CB Mods Premium Member

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    It is very timely that you posted this. I literally just got in from a sold out show of Les Mis we are running this weekend. Ours is a very similar design to yours, except it is 30' in diameter. You absolutely need to secure the motor in order for it to be effective. We have ours mounted into a steel frame and lag screwed into the stage floor with six screws. This is critical for safety and for proper operation. There should be no slack in the chain. The idea that you need to leave the motor slack to adjust for inaccuracy does not make any sense to me. If you do secure the motor, and are still are having problems, it sounds like you may have a tension issue. Are your tensioners in all of the way, or can you get them tighter? Another thought is how the chain travels around the wood of the turntable. We created a 0'-1" channel around the whole turntable for the chain to ride in, as opposed to just the bare end of the wood. This helped to keep it in place when we were setting it up, and gives it an absolute path to travel.

    An E Stop is a good idea. We just placed our in line between the controller and the motor. Sorry to say I have no schematic for you though.

    For added safety, we also have video monitors for the stage manager and the operator of the controller, so they can see a front on view of the turntable. This is for added reference.

    ~Dave
     
    Last edited: Feb 8, 2009
  4. DaveySimps

    DaveySimps CBMod CB Mods Premium Member

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    Arrrrr, Icewolf, you beat me to the draw and posted while I was typing! :)

    ~Dave
     
  5. draco17315

    draco17315 Member

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    We had a local company who does electric motors look at ours and give it a tune up and our engineer did all kinds of math based on the size of the turntable, the size of the sprocket, the weight divided amoung all the casters....etc....we added 2 screws to the chain tonight just to verify strength and the chain pulled the revolve around no problem at all, it's just we cant obviously use screws to allow the chain to "bite" for full rotations and reverse rotations.....as far as the control, we do have a professional speed control we purchased we just wanted to add an extra e-stop for safety, I guess my electrician would be our safest bet to add this feature...thanks for the info :)

    Joe
     
  6. draco17315

    draco17315 Member

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    wow..nice to see that I am not the only TD up late at night trying to solve issues.....LOL......yes, we used the design most people have used with what I call the oreo cookie platform, ply on top the ply in the middle but an inch or so shorter then an bottom rim of ply that it at the same distance forward as the top layer thus creating the "channel" for the chain to follow......I like the monitor idea as well......as far as the tension gears, do you mean can we put them closer together? right now they are about 5 inches apart, almost the width of the sprocket on the gear reducer, we could pull them closer togehter, do you think this might help?

    Joe
     
  7. DaveySimps

    DaveySimps CBMod CB Mods Premium Member

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    Sound like my tensioners are a bit different than yours, as ours have a screw that allow you to adjust the tension on them by turning a nut on the back end. I tried looking for pictures, but they are on the computer at work.

    Anything you can do to get the slack out of your chain is a good idea. Obviously, leave enough room between components for them to operate with out obstruction. If pulling them closer together creates more tension, I think this could be helpful in your situation based on what I can tell from your description. Good Luck!

    ~Dave
     
  8. draco17315

    draco17315 Member

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    thanks.......we'll need it.........LOL..........we'll have to post some pics or something when finished....our tensioners are two sprockets, one on the left outside of the chain and one on the right outside of the chain and the chain feeds around the turntable then channels through these sprockets and down the channel to the sprocket on the motor......

    Joe
     
  9. DaveySimps

    DaveySimps CBMod CB Mods Premium Member

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    Sounds like they should still do the job. Feel free to PM me if you have any more specific questions you think I may be able to help you with. I am happy to try and do so.

    ~Dave
     
  10. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    The motor should be stationary, that's why the system has tensioners (which for safety usually have some sort of mechanical overload protection, "weak link", shear-bolt, etc.). What surface is the sproket chain trying to grab on the edge of the revolve? One solution might be as simple as applying anti-slip non-skid tape.
    [​IMG]
    Safety Track 3200 Coarse Anti Slip Heavy Duty Traction Tape

    As to your deadman and E-Stop questions: wiring advice is really beyond the scope (and against the terms) of Control Booth. As said above, consult a qualified professional, one who can see the set-up and advise accordingly.
     
  11. draco17315

    draco17315 Member

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    Didn't see that about wiring, thanks........like I said, I'll have my electrician look at it..........but now that I think about it, there are tons of people asking for schematics of stuff....am I missing something?
     
  12. jwl868

    jwl868 Active Member

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    Maybe you have considered this, but step back and make sure that you have considered the safety aspects of the rotating equipment (such as motor, gear box, drum) and pinch points (such as chain and revolve). Guards and/or barriers may be needed to keep hands, loose clothing, headset cords, etc. out of harms way.

    Joe
     
  13. Footer

    Footer Senior Team Senior Team Premium Member

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    Also check your rights for the show, the "revolve" rights are hard to come by.

    Your winch must be bolted to the deck, if you must lag I would lag through a 4x8 of ply and stack weight on the ply. Also, use plenty of lags. You might want to look at buying a few "dogs", basically they are small halves of sprockets that can bolt onto the piece. Also, a proper tensioner need to be built. I usually try to build these into the winch frame, but I have also built s few that are deck mountable. Either will work.

    I am also concerned with the motor itself. Unless highly geared down, a 3/4 hp motor will not cut it. It has the power to run it, but may not have the power to start it, which could be why you are throwing your chain. Good luck, first time automation is a learning experience.
    Posted via Mobile Device
     
  14. draco17315

    draco17315 Member

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    Yes, our revolve is totaly secured, all "pinch" points are covered, there is a strationary platform surrounding the revolve and the chain is run through a channel that has a hinged top to access for repairs, the top is pad locked and our control box is detachable and also installed into a lock box. I appreciate the concern, but safety is one place I am not a stranger to....and in saying that, being safety minded, I also know that I appreciate all feedback and info because the moment I let my gaurd down and safety can go out the door, so thanks again and I will be sure to double tripple check everything. Oh and we also ran a training for running crew and will be having a seminar for the cast as well to go over all safety.
     
  15. draco17315

    draco17315 Member

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    My engineering student worked through all the math with his professors form the college. They spent alot of time figuring out the gear reduction, the size of the chain, the size of the sprockets, and alot of stuff that was way over my head. We tried the motor and chain with the set pieces on the revolve and used a few screws to give the chain something to bit for a test and with that bite it had no problem at all turning the entire revolve. We didn't just jusmp into this, we take safety and preperation very seriously and researched this since last year so we are not worried about the power of the motor, that is why we bought one with a gear reducer and then purchased the proper sized sprocket.....that being said, we obviously still ran into a few issues, power not being one of them, but it just goes to show, no matter how much planning, you still run into issuues so thanks again for all the help and suggestions....once we get everything figured out and runnig safely and smoothly, we will have to post some videos or picts. thanks again
     
  16. jmh5399

    jmh5399 Member

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    Hello everyone I'm the aforementioned engineer and this is my first post...

    I chose the 3/4 hp dc motor because we were limited by the current available from the wall (max 1 hp) and because of its price and ease of wiring and reversibility. With the 30:1 gearbox it can pull with 350 pounds of force with the turntable going at about 1 rpm.

    All we had time for was one test run so far, and at the moment there is nothing but plywood on the edge. We are first going to try cutting some inner tubes into strips and screwing them to the edge, and also attempt to put some nails around the edge to give it something to latch on to, as long as they still line up the second time the chain gets around. Before I even knew this thread existed I had already figured out that the weight of the chain acts as a tensioner, thus rendering the springs pointless.
     
  17. draco17315

    draco17315 Member

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    hey Jason....glad to see you checking this place out, alot of great info here!!!! Everyone, this is my former student crew member, my now head engineer, my assistant, and a great friend!!! We both appreciate all the info and feedback. We all know that some of the things that are asked of TDs and their support staff sometimes seems like asking for magic or a miracle!!!! In cases like that.....Jason is my Merlin or my Moses!!!! we will be sure to post some picts and stuff in the next few weeks!!!
     
  18. draco17315

    draco17315 Member

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    Just an update, we just used the Motorized spinning stage for our show "Annie" and after all of your help and the help of my Engineer, Jason, we got it to work successfully and not one problem with it durring the show!!!!!!!!!! I am starting Les Mis now, but soon I will find time to post some details and pictures.........thanks for all of your help gang........CHUKAS!!!
     
  19. Footer

    Footer Senior Team Senior Team Premium Member

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    Awesome, get some pictures up. Have fun with the Miserable Show.
     
  20. draco17315

    draco17315 Member

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    I will......just need to find time, Les Mis is in 3 weeks.....pics to post soon after that

    Joe
     

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