Constructing freestanding truss system

[whitehousejamie]

Hi All,

 

I have a good stock of Litec QX30 3.0m truss sections and corner blocks, and am looking for advice on the easist / safest way to constuct a freestanding 'cube' of 6m x 6m x 3m for exhibition work. It seems the obvious way would be to build the top square section first, then use a pair of stands to lift one side, then bolt the two legs on, then same on the other side.

 

Anyone know of a better / safer way?

 

Thanks

 

Jamie

[misterbassman]

The way I have done it in the past is to begin by building the top square, then raising this using 4 stands. Then build the four legs, and raise the top to just above its final position, place 2 legs under 2 of the corners, and have 2 people on step ladders ready (one at each corner), then lower the 2 stands and attach legs, and repeat for the other 2 legs.

[herb]

That would be one way.

Word of caution having seen this method fail spectacularly and expensively in the past.

Make sure you do not try and take it down while still rigged with whatever you are going to hang on it. Or put it up come to that. Makes for a very unstable load.

I believe someone out there has the imprint of a gobo wheel from a mac500 scarred into their face.

I had nothing to do with it ...just in the same room..running the opposite way

cheers

h

[whitehousejamie]

Thanks Bassman. The only problem may be lifting the square onto the stands. Even with 4 people, the QX30 is pretty heavy stuff.

 

Just wondering if there was any hoisting equipment that I can hire to do the job better.

 

Jamie

[Simon Lewis]

Just wondering if there was any hoisting equipment that I can hire to do the job better.

 

Could you not hire in four Towerlift 3's? OK, so you may duplicate the corner blocks, but this is how the truss is meant to be lifted.... Furthermore, you can build it, then raise it with its load.

[Soundie]

Thanks Bassman. The only problem may be lifting the square onto the stands. Even with 4 people, the QX30 is pretty heavy stuff.

 

Just wondering if there was any hoisting equipment that I can hire to do the job better.

 

Jamie

 

 

I frequently use 4x Manfrottos to lift a square of truss to the required height and then add the legs from ladders. This does require 4 hand to wind up the manfrotto stands. Just check the rating on the 'frotties, and do it unloaded.

[Roderick]

Personally I prefer Genie (or duct) lifts when constructing free standing truss structures. They are just more sturdy than your normal winch-up stands.

 

And make sure you put some decent base-plates under the uprights as they will give you most of your sideways strength.

If you don't have / want to use base-plates you may have to reinforce the corners with alloy scaff pipes.

[Seano]

I'd second the recommendation for Genie Superlifts or similar.

 

Four, rather than two - if you lift one side at a time you have horizontal movement and forces to content with as the truss pivots about the two feet it has on the ground, not good.

 

With care there'd be no reason not to rig/cable lighting etc before you lift, as long as you're well within the SWL of the lifts. Remember that as it goes up, inevitably one diagonal pair or the other will end up taking more weight than the other, so leave yourself an extra safety factor - at least one lift will be loaded with significantly more than 1/4 the weight of the whole truss at some point. (Theoretically, two lifts could end up with 1/2 each and the other two with no load at all if you don't wind the stands up nicely in sync). If using Superlifts or similar (something with forks and no clamps) remember that ratchet straps are your friends.

 

When winding up something like that, its best for one person to take the lead and actually call it like a dance teacher (ONE and TWO and THREE... etc). You may feel silly, but its worth it. Otherwise it always ends up with someone galloping ahead and someone lagging behind, however hard you try to keep the truss level, needless to say that is also a bad thing.

 

Just to state the bleedin' obvious, don't build the legs and fit them all at once. As the box goes up, fit the top section soon as, wind it up some more, next leg section etc. If your legs are 3x2m sections, you don't even need a ladder.

 

Best of luck.

Sean

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