# Affixing screen to truss



## fredthe (Dec 28, 2018)

So I've got a temporary install that needs a 7.5'x10' FastFold screen, rigidly attached to a horizontal truss (see picture.) Everything I've seen on screens and trusses generally involved hanging, but to get everything at the correct height the screen needs to be centered on the truss. Any suggestions for how to attach it? It's only about 32 lbs, so not very heavy, but I need something the PSAV riggers will find acceptable.


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## BillConnerFASTC (Dec 28, 2018)

I would be inclined to clip it (clamps) to the truss and then a off set "ring" at top that aligns with a lift line, truss to keep the crenn from rolling the truss at all. I would probably not be comfortable truss only attachment though if enough other weight on bottom of truss - several hundred pounds of lighting - it might be OK simply to brace it to upstage chords of truss.


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## egilson1 (Dec 28, 2018)

The light source has square clamps that should fit the screen frame. Those you can connect to a standard half coupler to make a “custom” cheeseborough to be able to connect the screen directly to the truss. Use 4 and it shouldn’t roll.


Ethan


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## fredthe (Dec 28, 2018)

BillConnerFASTC said:


> I would be inclined to clip it (clamps) to the truss and then a off set "ring" at top that aligns with a lift line, truss to keep the crenn from rolling the truss at all.


I was already considering something from the screen to the hoist chain to keep it from rolling the truss, though there will be close to 200 lbs of lights and speakers hanging form the bottom (I'd have more, but the venue only has 500 lb hang points). I guess to clarify my question, what specific clamps might you suggest for affixing the screen to the truss? I know some screen manufacturers design clips for this purpose, but DaLite isn't one of them. My LD suggested tie-wraps and, um, no.


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## RickR (Dec 28, 2018)

I'm not a rigger but I think you need a high attachment point. 2 side pipes clampec to the truss, if needed a top cross pipe to reach the clamps.


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## danTt (Dec 28, 2018)

The lightsource clamps @egilson1 suggested will work if you can get away with a potential bulge where you are clamping the frame. Alternatively, assuming this is a fast-fold screen that is designed to have legs at times as well, I might look at fabricating a bracket that has holes to line up to the holes on the frame for the legs, and putting a few half couplers on this. Add a wire rope safety depending on the specifics of your usecase if necessary.

Alternatively, in an indoor application I wouldn't feel too bad about zipties for positioning if you picked the screen from the bottom with cables for support and then held it in location with zipties or tieline. I think you might want a safety cable or too to prevent the screen from flopping over in the event that all plastic/rope attachments failed, but i think it could hold fairly well.


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## MNicolai (Dec 28, 2018)

Are there going to be movers of any kind on the truss? If so, you may have issues with the screen swinging around.


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## fredthe (Dec 28, 2018)

egilson1 said:


> The light source has square clamps that should fit the screen frame. Those you can connect to a standard half coupler...


Thanks, that's what I was thinking, but I couldn't find an appropriate clamp. I'll look at those, though as danTd points out there might be a bulge issue.


danTt said:


> Alternatively, assuming this is a fast-fold screen that is designed to have legs at times as well, I might look at fabricating a bracket that has holes to line up to the holes on the frame for the legs, and putting a few half couplers on this.


I was hoping to find something off-the-shelf, mostly because I won't have access to the screen frames to check alignment until the event (without extra effort, as I'm in Maryland and the screen and event are in Boston.)


> Add a wire rope safety depending on the specifics of your usecase if necessary.


I was already planning on one safety on each side, around frame and truss. It's rigged high enough that even if the safeties slip to the top of the frame, it'll still be above head height if anyone's under it.


> Alternatively, in an indoor application I wouldn't feel too bad about zipties for positioning if you picked the screen from the bottom with cables for support and then held it in location with zipties ...


Now *that's* an interesting idea! It would be simple to pre-fab the pick lines to the correct, matched, length. And yes, still safeties as backup.


MNicolai said:


> Are there going to be movers of any kind on the truss? If so, you may have issues with the screen swinging around.


No movers. There were plans initially for moving mirror type, but then we found out about the 500 lb limits (which was not indicated on the venue drawing.)


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## BillConnerFASTC (Dec 28, 2018)

fredthe said:


> Now *that's* an interesting idea! It would be simple to pre-fab the pick lines to the correct, matched, length. And yes, still safeties as backup.



Load rated zip ties.

This is very clean - some 1/8" wire rope from bottom of screen to truss and zip tie around mid point of screen to top of truss. It might rotate truss ever so slightly. Don't know if that would be a problem for your content.


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## lwinters630 (Dec 29, 2018)

fredthe said:


> So I've got a temporary install that needs a 7.5'x10' FastFold screen, rigidly attached to a horizontal truss (see picture.) Everything I've seen on screens and trusses generally involved hanging, but to get everything at the correct height the screen needs to be centered on the truss. Any suggestions for how to attach it? It's only about 32 lbs, so not very heavy, but I need something the PSAV riggers will find acceptable.


Da Lite makes fly clamps check fullcompass
*Da-Lite 29641*
Fast-Fold NXT Fly Bracket Kit

The fast fold has about 1 1/4 " square stock frame. You could use small rated chain or Blue water rope to wrap around it. Always check the rating first for your application. Use two 2 points about 6" in from each side. Run 1/4" shackle, thimble, 1/8 black wire rope up to truss.


Fast fold weighs under 60 lbs.


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## egilson1 (Dec 29, 2018)

lwinters630 said:


> The fast fold has about 1 1/4 " square stock frame. You could use electric mini clamp (home depot) they should fit around the sqare stock on the top frame. Use two 2 points about 6" in from each side. Run 1/4" shackle, thimble, 1/8 black wire rope up to truss.
> 
> Flatten it for the square stock. Either side up. Option for eye bolt.
> Fast fold weighs under 60 lbs.



How about we not recommend using non-rated hardware for suspending something overhead? Even if it’s only 60 pounds. The need to use properly rated hardware when ever you are suspending anything overhead cannot be understated.


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## lwinters630 (Dec 29, 2018)

egilson1 said:


> How about we not recommend using non-rated hardware for suspending something overhead? Even if it’s only 60 pounds. The need to use properly rated hardware when ever you are suspending anything overhead cannot be understated.


I have edited the post to reflect rated hardware.


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## Mike Donovan (Jan 2, 2019)

Happy New Year!

We fly screens on a regular basis during corporate season. We have fly kits that attach to our larger screens, but with our smaller screens, 9’x16’ and smaller, we rig right to the screen frame.

We have these black ~3’ long webbing straight slings. I forget what they’re rated for off the top of my head, but their rating is plenty for screens. The sling has an eye in either end, so we choke it through itself around the top of the screen frame (or around the fly bar of our bigger screens), pass it around the chord of the Truss, and finish with a shackle. For a 7.5x10, we’d use 3 slings: centre, then one each a foot or so in from each edge. Then add a couple of safeties between the frame and truss.

We also have some rated screw eye/trigger clamp assemblies that we normally use for our video wall. Sometimes we will clamp those to the Truss and shackle the sling to the eye. This then gives us some levelling options as the assembly can work similar to a turnbuckle.


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## Mike Donovan (Jan 2, 2019)

Mike Donovan said:


> Happy New Year!
> 
> We fly screens on a regular basis during corporate season. We have fly kits that attach to our larger screens, but with our smaller screens, 9’x16’ and smaller, we rig right to the screen frame.
> 
> ...



Sorry, I just reread your original post and saw that the screen is not hanging underneath the Truss. 

Rig the screen similar to a flat that is supported by bottom hangers: Build three points. Each point has a sling choked around the bottom piece of frame, a second sling choked around the Truss, and a piece of wire rope and shackles to get between the two. This will support the weight of the screen. Then make a lashing with slings or rope to secure the middle of the screen to the Truss so it doesn’t rotate forward.


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## AVShowNC (Jan 2, 2019)

fredthe said:


> So I've got a temporary install that needs a 7.5'x10' FastFold screen, rigidly attached to a horizontal truss (see picture.) Everything I've seen on screens and trusses generally involved hanging, but to get everything at the correct height the screen needs to be centered on the truss. Any suggestions for how to attach it? It's only about 32 lbs, so not very heavy, but I need something the PSAV riggers will find acceptable.



Cable Gliders. They attach to aircraft cable and allow for adjustment. Use them all the time.

A unique, self-locking, completely adjustable suspension device.


Instant and precise height adjustment along the length of aircraft cable
Gliders attach to steel cables using a unique 3 or 6 ball mechanism
Glider slides up and down the length of cable when depressing plunger
Locks solid when the plunger is released
https://www.stageriggingwarehouse.c...tStraightCategory=Rigging Hardware&SBCatPage=


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## danTt (Jan 2, 2019)

AVShowNC said:


> Cable Gliders. They attach to aircraft cable and allow for adjustment. Use them all the time.
> 
> A unique, self-locking, completely adjustable suspension device.
> 
> ...


The various versions of these are pretty neat, however it's really hard to find any that a) have any rating and b) are rated for overhead lifting. I've seen these fail in in impressive ways before if they are used improperly as well. Also, they will not work very well in this circumstance because the screen needs to hang above the truss, which even with completely adjustable picks is pretty hard to do with cable alone.


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## kicknargel (Jan 2, 2019)

Mike Donovan said:


> We have these black ~3’ long webbing straight slings.



I've shied away from rigging with nylon webbing because it won't stand up to fire or high heat. Too bad, because it's very convenient. But we've go to aircraft cable or chain.


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## BillConnerFASTC (Jan 2, 2019)

kicknargel said:


> I've shied away from rigging with nylon webbing because it won't stand up to fire or high heat. Too bad, because it's very convenient. But we've go to aircraft cable or chain.


Just curious if you know of any incidents if these being an issue in an actual fire in an occupied building.


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## kicknargel (Jan 4, 2019)

I don't. Just something I've heard from riggers time to time. In fact PSAV in-house crews (hotel ballrooms) have made me change nylon to steel rigging for this reason. (Not consistently.) So, it's one of those abundance of caution things.


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## RonHebbard (Jan 4, 2019)

BillConnerFASTC said:


> Just curious if you know of any incidents with *these being an issue in an actual fire in an occupied building*.


 *@BillConnerFASTC* Are you asking about fires involving equipment suspended by nylon slings in an occupied facility*??* If so, "Lettice and Lovage" featuring Dame Maggie Smith and Maggie Tyzack in Broadway's Music Box theatre in 1990 leaps to mind. 
Toodleoo! 
Ron Hebbard


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## BillConnerFASTC (Jan 4, 2019)

RonHebbard said:


> *@BillConnerFASTC* Are you asking about fires involving equipment suspended by nylon slings in an occupied facility*??* If so, "Lettice and Lovage" featuring Dame Maggie Smith and Maggie Tyzack in Broadway's Music Box theatre in 1990 leaps to mind.
> Toodleoo!
> Ron Hebbard


Any details?


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## RonHebbard (Jan 4, 2019)

BillConnerFASTC said:


> *Any details?*


 * @BillConnerFASTC* I was one of the touring IA assistant electricians with "Buddy Holly The Musical" around the corner at The Shubert. Many of us were hanging around outside, prior to a matinee possibly, when smoke belched out of The Music Box's front doors followed moments later by fire engines racing past. Our Local One production electrician was also the production electrician for "Lettice and Lovage" in The Music Box. The New York Fire Department took exception to little things like CD80 96 x 2.4 Kw racks raining down on them from the grid. I believe this was the fire that outlawed nylon slings for such purposes and brought about the insistence upon _GAC-flex_ fireproof flexible slings. "Lettice and Lovage" featuring the two Maggies Smith and Tyzack, was sold out to the walls. The fire department ventilated the building extensively, they hung work lights and kept right on running shows. My wife attended a performance only days later. As we shared the same Local One production electrician we were kept pretty much in the loop. 
Toodleoo! 
Ron Hebbard


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## egilson1 (Jan 4, 2019)

I’m a bit tied up tonight but I’ll post a rant about synthetic slings, steel, and fire sometime this weekend.


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## Jay Ashworth (Jan 6, 2019)

We're looking forward to it.

Ron, did you say they *flew the dimmer racks*??


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## RonHebbard (Jan 7, 2019)

Jay Ashworth said:


> We're looking forward to it.
> 
> Ron, did you say they *flew the dimmer racks*??


 *@Jay Ashworth* *Yes*. It was the fully loaded CD80 96 x 2.4 Kw. racks raining down through the smoke from the grid that particularly annoyed the fire fighters. Our IA Local One production chief electrician was also their production electrician thus we were kept well in the loop. In the IA tradition, our Local One production electrician was Jimmy (Something beginning with an 'M') Junior. His father was Jimmy Senior. In addition to those two shows on Broadway, young Jimmy was also the production electrician for the North American tour of "Starlight Express" that was simultaneously touring Canada and the U.S. in 1990. I was able to catch the in, out and a follow spot call while Starlight played Kitchener / Waterloo's Centre In The Square when I returned from Broadway. Kitchener / Waterloo is in IA 357's jurisdiction. *@derekleffew* Was this the "Starlight" tour your mate was with when he went from *"heels to wheels"?*
Toodleoo! 
Ron Hebbard


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## egilson1 (Jan 10, 2019)

Ok, finally getting back around to the post. Below are 2 images of slides from my training presentation. The first is a temp/strength curve for aluminum 6061-T6 truss. The second shows the average temp of a building fire, and how steels strength is reduced by heat. Take a look, and continue reading below. Not noted is that the melting point of nylon is about 473 degrees Fahrenheit. 





The first think to clarify is that I am a fan of redundancy, but it has to be done properly so if needed it will actually work. 

Second clarification is to delineate between a building fire or a specific threat source like a fixture/pyro fx. There is no question that a flame fx or well focused Sharpy can melt a synthetic spanset. But let’s focus on the building fire side. 

As the slide shows the average building fire is 1100 degrees farhrenheit. The 1/8” wire rope you hung your screen with now has a breaking strength of 680 pounds. And although this might be above the load of the screen, it’s possible the fire is a lot hotter that the 1100 F degree average. If it was at 2000 degrees F we now have a breaking strength of 200 pounds. 

What about the aluminum truss itself. Aluminum has a melting point of between 1080-1205 degrees F. So is the truss still even there let alone holding the payload? How about the screen material? Or it’s aluminum frame? Is the electrical cable?

The truth is in a building fire, our equipment will likley burn with everything else. The truss will fail, the wire will burn, the steel wire rope will be so brittle it will fail. 

From Harry Donovan’s Entertainment Rigging - “A theatre fire in Branson, MO lasted 15 minutes and melted the 1/8” GAC, and made the ¼” brittle and it broke.”

I have a bigger issue using climbing slings for rigging due to the difference in how they are designed and tested than because they might melt. 

But that’s just me 2 cents worth. 

Ethan


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## kicknargel (Jan 10, 2019)

Well. . . sure, everything will fail eventually. But given this info it still seems that the nylon sling will fail first. At 1100 degrees, the nylon is long gone, while the steel is still within a 3:1 design factor (which is too low a factor anyway) and should remain unbroken. And at 475 the nylon has failed, but the aluminum is at half strength (hopefully within its design factor as well).


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## egilson1 (Jan 10, 2019)

You’d be wrong about the truss. Df for truss is 1.2 to 2.


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## fredthe (Feb 22, 2019)

BillConnerFASTC said:


> Load rated zip ties.
> This is very clean - some 1/8" wire rope from bottom of screen to truss and zip tie around mid point of screen to top of truss. It might rotate truss ever so slightly. Don't know if that would be a problem for your content.




Mike Donovan said:


> Sorry, I just reread your original post and saw that the screen is not hanging underneath the Truss.
> 
> Rig the screen similar to a flat that is supported by bottom hangers: Build three points. Each point has a sling choked around the bottom piece of frame, a second sling choked around the Truss, and a piece of wire rope and shackles to get between the two. This will support the weight of the screen. Then make a lashing with slings or rope to secure the middle of the screen to the Truss so it doesn’t rotate forward.


As a follow-up, we ended up doing a combination of the above. Two slings (one on each side) from the truss to the bottom of the screen frame (they happened to be the correct length) and then load-rated zip ties to fix the screen to the truss. Very secure and stable, and we had backup safety cables for the zip ties though the load on the ties was minimal. 

Thank you all for your valuable suggestions and input!


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## MNicolai (Feb 22, 2019)

"Jet fuel can't melt steel beams."


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