Lifting Moving Lights

[rh01bellc]

hey there,

At the end of the year I am doing a show but the only access to the front of house bar is by building a scaff tower. I am planning to put the moving lights on the bar but I am not totally sure of the best way to get them to the top of the tower and on to the bar. Can anyone give advice on how they would do that? I have the possibility of having a climber on the crew so hes given me his suggestions, so I'm just trying to find out any other options to consider?

Thanks

C

[DSA]

Pass them up the tower?! How heavy are they?

 

Alternatively rope and pulley onto suitable point.

[rh01bellc]

Pass them up the tower?! How heavy are they?

 

Alternatively rope and pulley onto suitable point.

about 25kg - they are tourwashes. the problem is basically a "false roof" with the actual girders above it so there is only the IWB and the scaff tower. the danger is aswell that janitors rig it, which I am not happy about as I am the person with the experience, but its trying to get them up without damaging them.

[paulears]

if it was me, assuming the bar isn't on its safe weight limit, is lift the unit on two ropes round the bar - do these fixture have handy handles that rope will fit through? All you need to do is arrange the tower so the lift goes straight up next to it so you can stand on the top platform and just guid the clamps over the bar - with two people on the ground hauling it goes up quite easy - the friction going around the bar helps when they stop. Obviously you need to make sure you don't have to lean out of the tower, but it works quite well with a modest moving light weight like you have. Certainly rigging mac 250s this way has always worked for me. If you are doing it with students (or are one) make sure you or they can tie knots - most of mine couldn't!

[rh01bellc]

Thanks for that, I hadnt thought of doing it like that. At the moment I am a student, but a couple of the students are actually climbers themselves so I'll leave knots to them. the bar has a SWL of between 150 - 200kg (the company who installed it gave the details to the land lords rather than the people who need the information) but I think I will rig them while the bar is clear. Any other suggestions? Im trying to get as many options as possible! Thanks

[Tomo]

The sanest way of doing this is to use a suitable rigging rope as described by paulears.

Be aware that the load on the bar is slightly more than double the weight of the fixture - be careful that you don't exceed the rating!

(How much more depends on the friction and isn't easily calculated)

 

Don't try to pass Tourwashes up a scaff tower - it's impossible to justify this in a risk assessment.

 

In fact, I prefer to use a rigging rope for every kind of fixture - even parcans!

Makes my life up the tower much easier.

 

Tourwashes have handles that work quite well when roping them up.

 

The usual knot is a bowline - if your climbers don't know that knot, then they probably shouldn't be climbing!

 

For future reference, the two knots that you need to know in theatre are:

1) Clove Hitch - usually locked with a half hitch or two.

2) Bowline.

[rh01bellc]

Can I just ask what you would define as suitable rigging rope? I have always used blue plastic nylon rope - but then again its only been for normal generic lanterns such as fresnels and source 4s. Cheers

[danjshelton]

I don't know the Tourwash fixtures that well (Used them once, but didn't rig them) but is it wise to tie the rigging rope to the handles (presuming that you mean carrying handles?). I've been on jobs before with other freelance lampies and twice, on different occasions, seen people tie to the handles of Macs (Think it was 500's and 300's I've seen this happen on) and the handle has come off (Luckily they we're just starting to haul so they still had hold of the light.). If you think about the handle on 500/600's then there not particularly strong and just have 2 bolts holding them in place, which only go through the plate metal of the panel work.

 

Generally I usually tie off to the carabiner that is on the safety that hooks to the body of the fixture (A bit more substantial) on the safety point (That should be rated to hold a number of times the weight of the fixture (can't remember the exact ratio).

 

Dan

 

PS The company I was working for when this happened weren't renowned for there maintainence of fixtures (Same company both times, thought they would have learnt!)

[Don Allen]

Would the friction of the rope on the bar increase the weight of the fixture to more than twice the weight of the fixture as you have a portion the weight of the lifting person transferred onto the rope?

 

This is why pulleys are useful, to reduce friction. You just need to take the height of the pulley into account to make sure you can get the clamps onto the bar.

[Ben Bodsworth]

Can I just ask what you would define as suitable rigging rope? I have always used blue plastic nylon rope

 

Personally, being a climber, I wouldnt use blue plastic nylon for anything larger than a parcan.

 

I would use a static rope (used in abseiling), which will stretch slightly, but not as much as a semi static rope, used for climbing.

 

Anyone with any other ideas?????? afterall, we're all here to learn from eachother!!

 

Ben

[Seano]

Would the friction of the rope on the bar increase the weight of the fixture to more than twice the weight of the fixture as you have a portion the weight of the lifting person transferred onto the rope?

 

Yes. With a perfect frictionless pulley the pulley would load the bar with twice the weight of the fixture exactly, whilst its hanging on the rope. Thats because there is a rope emerging from either side of the pulley, both under the same tension - the weight of the fixture one side and the person holding it the other.

People tend to pull things up in arms-length surges, so the load would actually fluctuate between a bit more than twice the weight, as the fixture is accelerated upwards, and a bit less as it slows down again.

 

With some friction at the pulley (or where the rope runs straight over the bar), the load is higher as the fixture is accelerated upwards. On the fixture side of the pulley there is still the weight of the fixture plus a bit more to accelerate it upwards, on the other side there is the same again plus still more to overcome the friction at the top. When the fixture is at rest, the load is a bit less than twice the weight of the fixture in this case, the friction means it takes less that the weight of the fixture on the opposite side of the pulley to hold it in place.

 

Personally, being a climber, I wouldnt use blue plastic nylon for anything larger than a parcan.

I would use a static rope (used in abseiling), which will stretch slightly, but not as much as a semi static rope, used for climbing.

 

Not a particularly well informed climber though, it would seem..

 

Static rope does not exist as such, all rope stretches to some degree. Its because of this that what we used to call 'static' rope (used for abseiling, caving and hauling mostly) is now usually called semi-static. Its the same stuff. Also often called low-stretch (particularly by industrial suppliers).

 

Semi-static can be used for top-roping, where the anticipated fall factor is negligible, but should NEVER be used for lead climbing. If you are lead climbing on a semi-static rope: STOP NOW! (And thank your lucky stars you got away with it.)

 

Dynamic ropes are designed for lead-climbing. ('Single' ropes, usu 9.8mm - 11mm designed to be used alone, 'half' ropes and 'twin' ropes usu 7.8mm - 9mm designed to be used in pairs.) Dynamic rope is designed to stretch, and thus absorb some of the energy of a fall. Thats why they're not ideal for hauling, because they also absorb much of the energy you're trying to use to haul something. (Also, the sheath tends to have a looser weave, to make the rope more pleasant to handle. A side effect of that is to make them a lot less hard-wearing than low-stretch ropes.)

 

If cheap blue polyprop is the right size, strength isn't an issue, its strong enough. Really the only problem is that its nasty to handle.

 

Other alternatives are:

Yachting lines (braid on braid sheets are nice), which are specifically designed to be hauled by hand and the larger ones can be really nice to handle.

Arboricultural lowering lines, similar (kernmantle) construction to abseiling lines, but rather fatter and immensely strong.

Big fat solid-braid - the choice of most riggers chuffing up chains in arenas, but somewhat difficult to obtain and probably overkill for lampie.

 

I'm getting stong deja-vu here. I'm pretty sure I've posted a fair bit of on lines, pulleys and where to get them before (in a thread where several other people had done the same). I suggest a search.

[paulears]

The disadvantage of using pulleys (ignoring all the perfectly obvious advantages) is that it stops you puling the head to the hanging position - unless the pulley can be suspended from something above the bar, and that is usually more of a problem. The extra effort to get the thing moving upwards is considerable, but can be assisted by somebody giving the load a helping hand as it leaves the ground.

 

Rope wise, I tend to use the orange poly rope rather than the blue. I'm not sure why, probably the formulation, but it always seems a little 'slippy'. Although this could just be a different product rather than anything to do with the colour. Getting the things down with the rope doing an entire turn around the bar also provides a safer system, as the friction works for you, as a brake.

[landy]

On the pully front, an Opera Block from flints are worth their money 10 time over (under £30 if I remember correctly). Well made, simple and easy to use.

[Malcolm Gordon]

On the pully front, an Opera Block from flints are worth their money 10 time over (under £30 if I remember correctly). Well made, simple and easy to use.

£18.85 + VAT here.