fixing truss to scaff bars

[timmiddleton]

Hi

 

I have 3m trilite with stands etc but for an event at work I want to fix it to a lighting bar over the stage. However, I need to have the truss about 3ft below the scaff bar. I'm putting a couple of movers on the truss so I don't want it moving with them! What's the best way of fixing the truss to the bar?

 

Tim

[Jamtastic3]

Possibly Doughty clamps - either swivel or 90 degrees. They don't 'crush' truss when clamped tight compared to scaff clamps. Though they do cost a fair bit for just one.

 

I don't know. I usually go by the idea that scaff bar to scaff bar = scaff clamps, but truss to scaff bar = Doughty clamp or similar.

[johnhuson]

First of all have you calculated the weight of the truss and movers, and then established whether the bar you are hanging from is capable and certified to take the point loads you will be applying to it.

 

As an example a 3mtr length of Trilite (assuming it is genuine Trlite) weighs 5.25Kg, factor in a couple of average weight 250w movers at around 18Kg, a bit more for your rigging, cabling etc. you could be imposing point loads of around 25Kg assuming your hanging from two points. Although this doesn't sound like a lot you may find the struture your hanging from may not be able to support that. But you need to know if it will or not before you hang it.

 

As for your problem you would normally use steel wire drifts, using fabric slings to pick up the truss or some suitable clamp. If you are inexperience in rigging I would strongly suggest seeking some professional advice. Hanging things is a whole new teritory when it comes to safety.

[TommyToad]

I would use slings and/or wire.

And as John pointed out, do it right.

Normally people are very rarely allowed to "work" under hanging equipment without hardhats and proper safety equipment. Except in this business

[flypig]

Hi

 

I have 3m trilite with stands etc but for an event at work I want to fix it to a lighting bar over the stage. However, I need to have the truss about 3ft below the scaff bar. I'm putting a couple of movers on the truss so I don't want it moving with them! What's the best way of fixing the truss to the bar?

 

Tim

 

You should rig the truss to the fly-bar with FSWR (fly bar clamps to 2.5t shackles to 10mm diam FSWR to 2.5t shackles to 3t span sets (synthetic slings) on the truss), then hang your movers. Any touring gig fly truss with movers on it all the time with very little (if any) movement from the fixture. By hanging a truss from a fly bar you have two individual suspension sytems (the truss and the fly-bar), any movement from a fixture is dissipated very quickly through the cables.

 

Do check your weights though, allow 39.5kg per mover, 7kg per Lm of Tri, 8kg for top & bottom rigging per point and 7.5kg per 25 Lm of cable THEN add 10% safety margin. THEN add the original fly bar, THEN add 10% to the total and see if your points can take the load.

 

Other than that, why don't you just hang the movers off the fly bar?

 

If you really need to steady the truss you should 'Brail' (tie off with (min) 6mm diam sash cord or other) from the truss front and back (both ends) to something immovable in the venue.