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Author Topic: 4 bars on a truss  (Read 620 times)

Frank D. Campbell

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4 bars on a truss
« on: July 03, 2018, 04:35:50 am »

I apologize if this is a stupid question but has anyone attached 4-bars to a 2 point flat truss. I hope everyone knows by my description what I am talking about. I am looking to add some more lighting without creating a ton more work since most of this will be done from the stage. I own 3 4-bars and I thought I could connect them altogether on a truss that gets hung up in a trailer. But that is getting a little wide. So I have been looking around and found a 10 foot truss I could hang 2 of the 4-bars on the bottom. They also have T-bars on each side and I thought I could hang an additional 4-bar on each side too. For a total of 4 4-bars.
« Last Edit: July 04, 2018, 12:47:33 pm by Craig Leerman »
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Mac Kerr

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« Reply #1 on: July 03, 2018, 10:22:43 am »

I apologize if this is a stupid question

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Jeff Lelko

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Re: 4 bars on a truss
« Reply #2 on: July 06, 2018, 01:49:27 pm »

Hi Frank.  I’m not sure I fully grasp what you’re trying to explain, but The Light Source sells all sorts of clamps and junction components to build just about anything you’d like.  If the truss kit you bought is one of the light-duty Musician’s Friend type I’d suggest the wrap-around style of clamps.  Just make sure you get the right size!  Sharing links of exactly which lights and truss you bought can help get you better advice too.  Hope this helps!
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Mark Cadwallader

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Re: 4 bars on a truss
« Reply #3 on: July 06, 2018, 11:41:30 pm »

Frank, the load carrying capacity of truss should be listed by the maker for a maximum center point load, a load at the third and/or quarter points, and total uniformly distributed load for various lengths of truss assembly.  The rating should also list the deflection from horizontal at those loads, which will increase as the truss gets longer and/or the weight increases.

As with suspending anything over people's head, allow for a comfortable margin of safety by not loading truss to its max allowable load.  Nobody should get hurt or die due to falling gear or failed truss or lifts.

When you look at how much load you have on a truss, don't forget to take into account the added weight of cables and cords, as well as clamps or other stuff loaded on the truss. It adds up in a hurry.

An I-beam like truss can be very strong with static hanging loads, if it is well designed and constructed. An extension ladder, while in the same basic shape, is not designed or constructed for overhead rigging.

So check the load specs on the specific truss you have, and see if it will handle the weight of your lights and cabling.  Also, if you are using stands or lifts to hold up the truss, be sure to take those load ratings into account too. The higher you lift, the sturdier and stiffer they need to be.  If you think it looks sketchy or marginal,  it probably is.

Finally, I assume you are doing this indoors. If you are out where there might be wind loads you will need to calcuate those loads too, with an even higher safety factor.
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Frank D. Campbell

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Re: 4 bars on a truss
« Reply #4 on: July 08, 2018, 08:18:00 pm »

Thank you both. I should have explained better. All I have now are the stands that go with my 4bars. I thought I would see if anyone  had ever done this. I don't have the truss yet. Wanted to make sure it was doable first. I did find a guy who did it and it looked good. I was hoping to get the 4bars on a truss because I hate the light stands. And I thought I could leave them hooked up and hang them in my trailer. Thank you both for the advise! What I would like to do is get a 10 foot I-Beam truss and hang two 4bars on the bottom. Center each 4bar on each 5 piece section. then hand another 4bar on the top but kind of upside down right in the middle  where the two 5 piece sections meet. Then one small special on each end. The 4bars only weigh 29lb a piece so I'm not looking to have something too heavy. I want to make it as easy a possible.
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Mark Cadwallader

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Re: 4 bars on a truss
« Reply #5 on: July 08, 2018, 09:10:42 pm »

If you can find a local vendor where you can take a good look at the items you plan to buy, I suggest that you do so.

If you are a one (or two) person operation, you need to think through exactly how you are going to deploy your setup. Are you going to assemble your two pre-rigged 5' truss segments on the ground?  Will you (and your helper) be able to safely lift that assembly up onto your stands and secure the truss to the stands?  I dunno; there are lots of different setups available, so I can't comment what is feasible.  For my own box truss, I assemble it on the ground, lift up each end and secure it to the truss adapter on my crank-up stands, then I hang and cable the lights. Once that is all done, a helper and I raise (crank) the lifts up to the correct trim. Finally, I go up a ladder to do any final focus corrections I need.

I agree 100% with your artistic sense that a clear span for hanging light looks a lot better than individual stands.
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Rob Spence

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Re: 4 bars on a truss
« Reply #6 on: July 09, 2018, 12:31:10 am »

Thank you both. I should have explained better. All I have now are the stands that go with my 4bars. I thought I would see if anyone  had ever done this. I don't have the truss yet. Wanted to make sure it was doable first. I did find a guy who did it and it looked good. I was hoping to get the 4bars on a truss because I hate the light stands. And I thought I could leave them hooked up and hang them in my trailer. Thank you both for the advise! What I would like to do is get a 10 foot I-Beam truss and hang two 4bars on the bottom. Center each 4bar on each 5 piece section. then hand another 4bar on the top but kind of upside down right in the middle  where the two 5 piece sections meet. Then one small special on each end. The 4bars only weigh 29lb a piece so I'm not looking to have something too heavy. I want to make it as easy a possible.

That’s around 100 lbs on an I-beam truss. Should be fine for 10’. I find it to be ok upstage.
It may be kinda short for downstage once you have to take into consideration the tripod legs of each stand. Really only gets you 6-7 ft of clear space in front of the stage.

I suggest you set up your 2 four bars on stands and set the uprights at 10’ and see if that works for you. You may be surprised at how short it is.

To get any longer than 10’ you need to go to triangle or box truss. On-stage used to offer a 5’ extender but discontinued it I presume due to excessive front to back flex.



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Jerome Malsack

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Re: 4 bars on a truss
« Reply #7 on: July 10, 2018, 11:59:07 am »

What I did with the 10 ft  I beam is I added a 5 foot to each side. with 4 legs and yes the stands take up a good amount of space.  The 2 5 foot legs allow me to z or u the stage and provide more stability.  Along with projection screens on the 5 foot wings it looks like a larger stage. 
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Frank D. Campbell

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Re: 4 bars on a truss
« Reply #8 on: July 10, 2018, 03:12:53 pm »

So I think I have it figured out. I like the Cedarslink 15ft Truss with stands system. It is rated at 330lb I wont need 15ft but I suppose you never know and its only 10 bucks more than the 10ft. I like the Light Source mini clamps rated at 150lbs each. Way more than I need but I would rather have more if I decide to add more lights. As of now 3 4bars weigh 90lbs. I would like to add some kind if special on each end. Something small and light that spins or has some kind of movement. Any suggestions? Maybe something that changes color when I ask it too.
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Jeff Lelko

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Re: 4 bars on a truss
« Reply #9 on: July 10, 2018, 04:05:13 pm »

What I did with the 10 ft  I beam is I added a 5 foot to each side. with 4 legs and yes the stands take up a good amount of space.  The 2 5 foot legs allow me to z or u the stage and provide more stability.  Along with projection screens on the 5 foot wings it looks like a larger stage.

I really like this idea.  Lots of options that look slick at a great price.  I'll have to file this away for possible use myself.

So I think I have it figured out. I like the Cedarslink 15ft Truss with stands system. It is rated at 330lb I wont need 15ft but I suppose you never know and its only 10 bucks more than the 10ft.

There's a bit more to the puzzle on this than just safe working load.  Truss kits like this tend to not do so well with heavy single fixtures.  I'm sure somewhere in the disclaimers it says the 330 pound rating is for an equally-distributed load...not that you're going to exceed it with what you have...just pointing this out. 

A bigger concern you might want to think of is that you'll have to join 3 sections of I-beam.  From experience, this can be a real pain.  Sometimes they pop together easily, sometimes (usually) they don't and are very fidgety.  When needing super-light duty truss like this I always traveled with the 10ft stick together and used something like Global Truss when needing to piece larger assemblies together on site.  The junctions on this particular kit don't look too bad, but still worth consideration.

Other food for thought is if you want a crank-up option, or at least something such as the Ultimate Support options that have self-acting brakes.  They're not that much more and once you use them you'll never go back!

I like the Light Source mini clamps rated at 150lbs each. Way more than I need but I would rather have more if I decide to add more lights.

I still vote for an O-clamp.  They won't dent or scratch up the truss like C-clamps do.

I would like to add some kind if special on each end. Something small and light that spins or has some kind of movement. Any suggestions? Maybe something that changes color when I ask it too.

The Martin Wizard style of effects are still my go-tos when looking for a lot of output and variety in a single fixture.  Not terribly small and definitely not cheap, but very effective.  Of course this will bring up the controller discussion, so what are you using right now?  Good luck!

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Frank D. Campbell

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Re: 4 bars on a truss
« Reply #10 on: July 10, 2018, 09:09:50 pm »

I will most likely almost always use a 10-foot section. Won't have much call for the 15 but nice to have it just in case. I will be leaving the 10-foot section together as well. My Controller is an Elation. I had someone program it for me. They made the top eight buttons into eight scenes. I didn't know if I could run some par 56 leds and two specials and be able to control them as well.
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Jeff Lelko

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Re: 4 bars on a truss
« Reply #11 on: July 11, 2018, 06:03:40 pm »

My Controller is an Elation. I had someone program it for me.

An Elation what?  Elation makes a wide variety of products from the very small/basic to large(r) and decent.  The specifics will determine whether or not it's possible to control more units along with some effect lights.  My guess is that yes, with careful programming and perhaps a bit of shoehorning you'll be able to make it work, but as an aside I strongly encourage you to learn how to program your controller.  It'll really help you get the most out of your investment and can also open up other possibilities for further expansion.  Good luck!
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