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Moving Yoke for Light House

Discussion in 'Lighting and Electrics' started by thelightguy87, Jul 23, 2008.

  1. thelightguy87

    thelightguy87 Active Member

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    I'm working on a show called "The Foghorn" It is inside a lighthouse and we are looking for a practical rotating light fixture. we also own a few Robe Color Wash 575AT fixtures. In a production meeting about this, it was asked from the director who is unfamiliar to lighting technology, why can't the light make continuous rotations. I thought about it, and although I've not torn a moving yoke fixture apart entirely, so i don't know what physically stops it, I didn't have an answer for him. I thought maybe it was wires, then i thought it would be able to feed wires through the yoke. And since the fixture can already do a 540 degree rotation, can anyone explain whats stopping it, and or why it can't just continuously rotate? My last guess is a way of tracking the position, having a stop point, so you can tell where the fixture is in comparison to its home location.

    Also, does anyone know of a fixture that CAN make continuous rotations?

    Thanks
     
  2. Sayen

    Sayen Active Member

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    If it's a set piece and doesn't have to be very bright, what about a cheap DJ light? I don't know specifics, but I've seen a few that just swirl endlessly.
     
  3. drawstuf99

    drawstuf99 Active Member

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    I've seen some of those rotating beacon lights that are quite large and powerful--not your average "party store" beacon light. Maybe take a look at those if that's the direction your leaning towards?
     
  4. gafftapegreenia

    gafftapegreenia CBMod CB Mods

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    I think you are over thinking this. Unless it has to be extremely bright, your stage is huge, or change colors, I don't see a need for a moving light.

    First, all traditional lighthouses lenses are just huge Fresnel lenses. A suitable look-alike could be something like this: Revolving Beacon for Lawn Lighthouse Either the first or second item on that page has plastic "bulls eye" (step lenses) lenses that look like enough like fresnels to work.

    The other option is a cheap DJ light. However, those use rotating reflectors, and while that works, it won't have the "realistic" look. They also rotate a lot faster than a more traditional lighthouse beam.

    Some lighthouses didn't even have rotating optics, but rather flashing lamps. Unless it must rotate, there is always that option too.

    My imaginative side tells me that three, 6" or 8" (or larger!) Fresnel lenses could be attached to a rotating platform with a lamp in the center.

    My last idea is to get the standard in rotating police beacons for Broadway shows and the like. the Mark 12. Any respectable rental house should have some available.
     
  5. drawstuf99

    drawstuf99 Active Member

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    The Mark12 above looks almost exactly like what I saw used. You can control the speed and intensity.

    Surely it wouldn't be that hard to wire up a small, low voltage motor (this is assuming you know what you're doing and have some skill in electricity) to some wood and bolt a fresnel-like fixture to it.

    Think about how you're treating what this fixture is incased in, too. Is it slightly diffused, fogged up? Or, is it clear as a every-day window? If it was fogged up--say, if it's during a storm scene or something--it would probably look the same to have a beacon light as a slightly more complicated fresnel light.
     
  6. thelightguy87

    thelightguy87 Active Member

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    the reason i asked about the moving light is because thats what the design staff specifically wants to use because we already own them, and the speed/intensity and such can be controlled via console. I'm co designer for this show, so i'll mention to my partner our other options and then see what the staff thinks. We would be using a wash fixture so it would have the fresnel lens, and possibly modifing it more, we talked about putting a clear case on the outside with large fresnels lenses on the outside, to appear to be a larger lamp. But i had issues with that because i didn't want to strain the motors in the fixture with extra weight. the light house is pretty big so we need a light source to compliment its size. but i made notes of all your ideas and will bring them up in the next meeting.

    thanks
     
  7. Pie4Weebl

    Pie4Weebl Well-Known Member Fight Leukemia

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    in the neck of the unit there is a physical pan stop piece which catches it at the end of the rotation, it is not something you want to mess with. The unit homes off it these two pan stops and every position it can hit is relative to these two stops.

    We just finished fixing a broken pan stop on a mover damaged by a certain municipal theatre group which won't be named. and it was a total pain.
     
  8. BillESC

    BillESC Well-Known Member Premium Member

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    The simplest answer is to get a display rotator with a PTO and mount a fresnel to the top and let it go.

    [​IMG]
     
  9. soundman

    soundman Well-Known Member

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    Not to mention just stopping it for homing tracking purposes the had stop also prevents the wires for twisting up too much and getting damaged.

    If I were you I would build a custom fixture for it with a lamp that is stationary and lens that rotate.
     
  10. soundlight

    soundlight Well-Known Member

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    As has been mentioned - a regular moving yoke fixture cannot move in continuous rotation for a few reasons: 1) hard stops and calibrations. This is how the fixture homes itself and determines where it is. 2) Wiring harnesses. Most moving lights, to the best of my knowledge, do not use brushes at the yoke and tilt positions, so they are not able to spin continuously or else the wires will twist too much and either stop the fixture, break the PCB, break the connectors, or rip themselves.

    The moving light that I know of that can complete continuous rotation is the Morpheus Panabeam XR2, which can spin in continuous motion in both axes of movement.
     
  11. BillESC

    BillESC Well-Known Member Premium Member

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    Why would one need to "build a custom fixture for it with a lamp that is stationary and lens that rotate" when the solution I offered is so simple? Any I might add inexpensive.
     
  12. ship

    ship Senior Team Emeritus Premium Member

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    Got some really old PAR 36 low voltage spinning lights about the shop, even a MR-16 newer version, but was once tasked with making a 10 degree S-4 Leko into a light house effect. Didn’t know at the time ETC had pre-made brackets so I made my own balancing the fixture yoke brackets. Worked well but took some time. Still the fixture balanced and the contraption worked well, the only limitation was the spinner itself one out of three stopped working and needed a replacement.

    A similar spinner can also do or pass DMX, though you would have to do a custom two circuit version of it with isolated ground for that to work. Done DMX thru work light cable reel spools before without a problem, same type of thing and system so as long as you can get both power and three circuits for the dmx, can be done with the spinner. LED's on the other hand could work with the spinner in isolating the power outlet to the control circuits as long as the shared drain wire doesn't have a problem with frame grounding.
     
    Last edited: Jul 23, 2008
  13. soundman

    soundman Well-Known Member

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    Personal preference and the options it will give me. Like many things in theatre most people here would solve this problem in there own way that is different than others. Depending on how bright this needed to be would also affect me choice. Anything over 100 watts I would probably use your way if possible because of the heat issues.

    Cost might be another reason to pick shop built. At school my labor costs around $0 an hour and most of the parts I would need to make this happen I could find in out automation cabnit , the junkyard or make a case for getting them because they would be useful as stock items. Fresnel lens are pretty easy to come by even more so if I do not damage them in a way that would prevent them from being returned to working fixtures.
     
    Last edited: Jul 23, 2008
  14. BillESC

    BillESC Well-Known Member Premium Member

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    If you can build a device that will rotate a fresnel lens arount a 500w BTL for under $ 100.00 then bravo to you. If not, my solution has merit.
     
    Last edited: Jul 23, 2008
  15. TimMiller

    TimMiller Well-Known Member

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    One thing you can do with some fabrication and a little time in wood or metal shop is mount up a 100 watt light bulb to a base, then they sell these lazy suzan things at home depot to built rotating tv mounts and things out of, they are not completely solid they have a big hole through the middle so you can run wires through (its like a spinning doughnut piece of metal). Take that and bolt a round piece of wood or metal to it (before you bolt up the piece, cut a grove around it for a belt (make this piece big around, it will be used as a gear reduction to slow down the motor). Then run a belt aroudn it and connect it up to a 12V or 120V motor that has a little pully. Then attach some lenses around in a circle on your doughnut spinner. They will spin around the fixed light bulb giving you a good light house effect.
     
  16. ship

    ship Senior Team Emeritus Premium Member

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    that would be another solution and interesting. A bit of work but only a question of spinning the spinner really and shielding the light.

    Could also do a MARs light type fixture with one lamp removed and NSP lamp instead of MSP lamp. Did a simiar to Bill's solution in the past and it worked well with the 10 degree Leko mounted atop otherwise in quick/done and or overall can probably rent the spinners from any number of companies and mount what ever fixture you want atop.
     
  17. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    Tell us more about the scenic design, thelightguy87. The lamphouse portion of a lighthouse is always circular and tiny, maybe only one to two feet larger than the light source and lenses. That doesn't provide much in the way of blocking, and there's only room for two characters. Not to mention that to be realistic, the source is going to have to appear blindingly bright, to both cast and audience (2000W Incandescent, minimum). A 100W bulb or Marz light probably will not give the effect desired.

    Now if (most of) the action takes place in the lamp keeper's quarters, that's totally different.
    [​IMG]

     
  18. ship

    ship Senior Team Emeritus Premium Member

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    but that's real fixture. Is this a simulated look with un-specified source or a prop light? Sorry probably missed that part in this above image I did consider origionally in how to do it but in later finding out I could just do Lekos in the beam was all that was important.



    IF the above image is prop light, full wattage might be a bit bright given proximity to audience unless up on some huge tower. Given that any number of ideas can work for doing it on stage especially the rotating lenses and light baffle fixed light given the above image.
     
  19. thelightguy87

    thelightguy87 Active Member

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    wow lots to think about. Scenic design is still in the works, as we just had our first production meeting. But most of the action takes place near the light source, but on a balcony, then they turn on the light, and eventually make it to the basement after the lighthouse is wrecked by a giant monster. I'm going to bring up a lot of these different ways to make our own light source instead of using a moving light because in discussion the director did ask about the tower being able to come crumbling down, or part of it at least. The tower is to be about 17ft tall, with the audience about 15ft away. The stage is a modified thrust. The reason my co designer, who is also my TD, wants to use the moving light is, and because it can't do a continuous 360 rotation, to make a pass, then turn off and go back to where it started, then turn on and make a pass again, and repeat. Which the director liked that idea. So I think they'll still vote towards the moving light, but i am intrigued and for the safety of the fixture if we do make the tower fall, I'm gonna vote for something other than the moving light. and again, thanks for the help
     
  20. TimMiller

    TimMiller Well-Known Member

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    whenver i have done a destructed look, i would have the monster attacking the lighthouse, maybe have some bricks falling over, then go into a black out. Wheel away the lighthouse, bring out another piece that looks like the lighthouse, only destroyed, lights up continue into the next scene. You could use the moving light, what i would do, is once it pans around part way, have it black out, then tilt over to the other side and then continue around. It will look less weird than having this thing flying back and forth. BTW, i saw a lighthouse on the discovery channel and the coast guard was changing out the lamp. It was a MSR1200/2 (cyberlight lamp) there were two of them that rotated around, one on each side, then if one were to go out, it had a spare it would automatically switch them out and continue on. It worked much like an over head projector with a spare lamp, you would just turn a knob that would pull the dead lamp out of the socket and at the same time push a new one in. I would just use the fernel lenses you have laying around for the demolished lighthouse.
     

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