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Author Topic: Problems erecting large projection screen  (Read 938 times)

Lee Douglas

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Re: Problems erecting large projection screen
« Reply #10 on: October 20, 2018, 10:26:49 am »

Twice a year?  Borrow another 10' ladder from someone in the civic organization.  Problem solved. No cost.  This, of course, presumes that all stability and liability issues have already been sorted.
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Jeff Lelko

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Re: Problems erecting large projection screen
« Reply #11 on: October 20, 2018, 10:37:36 am »

Even though I am not in the business, I am mechanically inclined and have always had a good feel for balance. I don't understand what you are envisioning WRT tipping. In what direction? There is bracing in all directions. Or do you mean the legs could actually break?

Back of the envelope analysis:

Your stands weigh about 15 pounds each...your screen weights 36.  In a best case scenario that'd put your center of gravity a little more than 50% up the mast - realistically probably closer to 65% - and this is a 12ft mast.  Even from just a statics standpoint it wouldn't be that hard to push past the tipping point.  Now you add in the fact you have over 11,000 square inches of screen to help enact a moment on the stands - they won't stand a chance if anything more than a slight disturbance comes their way.  Remember, it only takes one tip-over to crush little Johnny (who's father is a lawyer) and be in a world of hurt - especially when it's discovered that this is a home-brewed rigging solution.

I see three possible solutions that pass the sanity check here -

  • Install hanging brackets in all the locations that you've ever use the screen.  30 brackets for 15 locations isn't that many.
  • Buy a much more substantial tripod/truss kit that uses crank-up tripods and a full span of truss between the two.
  • Rent the proper solution for the 2 times per year you need it.

Anything else is just asking for a law suit in my opinion.  Hope this helps!
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Erik Jerde

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Re: Problems erecting large projection screen
« Reply #12 on: October 20, 2018, 12:31:20 pm »

No, it will never be outdoors. I was referring to the ballrooms that split up into sections, which by my count gives 15 possible locations for the screen including walls and corners.

Even though I am not in the business, I am mechanically inclined and have always had a good feel for balance. I don't understand what you are envisioning WRT tipping. In what direction? There is bracing in all directions. Or do you mean the legs could actually break?

You’re hanging the screen from the tripods, not rigidly attaching it.  You can’t rely on the screen to act as an adequate cross-brace to counter-act the inward pull put on the tripods by the screen.

At the end of the day you did come here for advice from pros.  The people here are serious pros who have spent careers studying and practicing the craft of safely hanging very heavy things over people.  We carry insurance are not cavelier about rigging of any sort.  Honestly the excuse of not enough money just translates to shouldn’t be done at all.  In reading your responses it feels like you’ve come here for affirmation not actual instruction.  Since you’ve admitted that you’re not in this line of work why don’t you tell us what you’re an expert at and then we can all take a shot at telling you how to do it?
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David Sturzenbecher

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Re: Problems erecting large projection screen
« Reply #13 on: October 21, 2018, 06:23:38 am »

It's a 150-inch Dalite screen and a JVC DLA-HD1. We have been using it for Superbowl for several years, hanging the screen from permanent brackets at one end of a ballroom.

Pretty sure you are now on record stating on a public forum that you are willingly violating federal copyright laws. 



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Joe Mirabile

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Re: Problems erecting large projection screen
« Reply #14 on: October 21, 2018, 09:19:31 am »

You’re hanging the screen from the tripods, not rigidly attaching it.  You can’t rely on the screen to act as an adequate cross-brace to counter-act the inward pull put on the tripods by the screen.

I have no problem going back to my original plan of adding a crossbar at the top. Or a truss if you think that would be even better. I can add a crossbar at the bottom too if that would help. The fittings are readily available.

Quote
At the end of the day you did come here for advice from pros.  The people here are serious pros who have spent careers studying and practicing the craft of safely hanging very heavy things over people.  We carry insurance are not cavelier about rigging of any sort.  Honestly the excuse of not enough money just translates to shouldn’t be done at all.  In reading your responses it feels like you’ve come here for affirmation not actual instruction.  Since you’ve admitted that you’re not in this line of work why don’t you tell us what you’re an expert at and then we can all take a shot at telling you how to do it?

I mean no disrespect. As is often the case with words on a screen, the attitude of the author is often misinterpreted, and/or the author did not do a good job of conveying attitude. I came to a forum in which I shouldn't belong, asking for advice on getting the proper leverage or other ideas on actually erecting the existing contraption I put together. You all raised red flags about the contraption itself, which I appreciate. The last thing I want or need is damage or injury. But I am constrained by the client WRT cost and their aversion to renting things. They always want to own stuff even though I am only aware of two times per year this will be used. Their thinking is that owning gives them the freedom to use it whenever they want.

So I am not ignoring the suggestions. But I have gravitated toward the ones that are feasible under the (albeit unrealistic) parameters. Adding crossmembers, crank-up tripods, pulleys, etc. are things I can do without throwing away the tripods I have. Those tripods got rave reviews in the places I looked, and many of the reviews came from pros. They are using them for the intended purpose though; I don't think any of them were holding a screen. I was also given less than one week to come up with something before a gala they had last week. I normally do exhaustive research before deciding what to recommend, and if I were able to come here beforehand, I probably would have ended up with something better, and maybe even within the budget. The first place I went was screen manufacturers looking for stands made for the screen, and I got nowhere with that.

Since you asked, I have been an I/T consultant for 35 years with specialties in networks, servers, internet connectivity, operating systems, applications, and the integration thereof. Digital convergence is another specialty of mine. I do not like my advice being ignored either, and I did not intend to, nor believe I did, do that here.

I do have a final question, and this is not snark, I genuinely want to understand. With what I have now, how would the failure manifest itself? I am just trying to envision what the actual failure would look like. The examples of it tipping forward into the audience ... are you saying the tripod legs or masts would bend or break? Or would something else happen? The clamps holding the mast sections together are very tight, so I don't think they could collapse. The eye bolts/screen carabiners are also thick steel.

Thanks guys!

« Last Edit: October 21, 2018, 09:29:58 am by Joe Mirabile »
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Joe Mirabile

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Re: Problems erecting large projection screen
« Reply #15 on: October 21, 2018, 09:22:15 am »

Pretty sure you are now on record stating on a public forum that you are willingly violating federal copyright laws.

Not me personally, but it is something they discussed the first year (actually it was after I told them about it after hearing of a case on the news). It is a non-profit and they do not charge admission. They do collect "donations" for the food. And they advertise it as "The Big Game" lol.
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Marc Sibilia

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Re: Problems erecting large projection screen
« Reply #16 on: October 22, 2018, 01:41:08 pm »

I removed the top cross pieces and cut them to one foot long and have them pointing forward with an eye bolt near the front, to which I can hang the carabiners on the ends of the screen.
...
The problem there is the legs get in the way. They each come out 2'.

What you are doing is downright dangerous.  By hanging the screen out in front you are giving up at best half of your stability (one foot out of two feet), and worst case nearly all of it.  A two foot reach leg on a tripod only has a support base size of one foot (see this prior post).  If you happen to put the long leg facing back, the thing is almost guaranteed to tip.  Wrong tool for the job.

Ignore this advise at your guests' peril.

Marc
« Last Edit: October 22, 2018, 02:41:24 pm by Marc Sibilia »
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Joe Mirabile

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Re: Problems erecting large projection screen
« Reply #17 on: October 22, 2018, 03:02:20 pm »

One correction with your note, the screen currently hangs from a 1-foot crossbar pointing forward. From front to back, it is 2" of crossbar, then the eyebolts/screen, then 3" to the mast, then 1.5" diameter of mast, then 5.5" of crossbar behind. I have decided to remove those crossbars and add a full-width crossmember at the top (either bar or truss), put weights on top of the back legs during use, and attach the screen directly to the crossmember instead of hanging it loose.  I am NOT going to stop using these tripods or have them rent anything for events. This board will have no liability in lawsuits resulting from damage/injury/death.

And with that I will take my leave. Thank you.
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Rob Spence

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Re: Problems erecting large projection screen
« Reply #18 on: October 22, 2018, 08:11:25 pm »

I have a pull down screen I use for Super Bowl parties at my house.

I have a pair of old Atlas speaker stands (for old 1960s paging horns). I got a length of 3” PVC pipe 2’ longer than the screen case and bridged the stands. I ran a pair of eye bolts through where the screen supports were and used a couple of snap rings to attach the screen.

Then two of us lift it up and the pull done the screen.
Works a treat. Wish I had a bigger screen though.



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