Flying truss using gripples

[Seano]

Gripples are not generally accepted as appropriate tools for rigging anything other than decor.

 

In spite of the thread necromancy ^^ this ^^ still applies. If anything, they're less generally accepted for floaty-light decor now than they were then.

 

Soft eye steels are deprecated also, really want to see a thimble in a crimped eye.

 

Is there any good reason why you can’t just have proper steels made to the correct sizes (they are surprisingly cheap to get properly made, certified ropes from a “brand name” rigging supplies company) and use those for your primary dead hang?

 

Also, ^^this^^.

 

Give Rope and Rigging a call. Also perhaps the competition just around the corner from them at Rope Assemblies.

 

If you want the convenience of quick and easy adjustment, look at Reutlingers. Expensive but secure, extremely neat, quick and easy to use. Used in conjunction with black steel with a crimped hard-eye one end and a fused tapered end the other you get a really nice re-usable light duty drift. Much more expensive than the Gripple assemblies you link to, but they belong in the bin after you've used them once. (Arguably before you've used them once.)

 

You are also wrong to assume that PA is a static load - the vibrations in fairly modest used definitely apply forces to your rigging equipment far outside the normal parameters of a “static” load..

 

{{citation needed}}

[empyfree]

I use, and don’t like using, gripples fairly regularly for alll sorts of things. Other than opinion what is wrong with using them given they are tested, and have a specified SWL? If they fail under their SWL surely they’d be in court all the time?

 

I’d also counter the argument about a speaker not being a static load, they’re a darn sight more static than a lot of air handling trunking that is hung on gripples in roofs.

[ImagineerTom]

A properly specd and set up PA system being used carefully and properly is a static load. Something not hung properly, poorly specd and being over driven (or with lots of base being sent through flown elements) is a different story. I’ve stood next to enough flown speakers that were moving and providing more dynamic forces than the moving lights in the venue to know that when someone shows limited experience / knowledge and starts asking about flying PA systems then by default I should assume the worst possible use and scale back my recommendations as more information comes to light rather than the other way around.

 

Gripples - on the makers website they only ever seen to be used in light duty situations and generally for horizontal rigging (ie cantenary wires) with an emphasis on using them in agricultural and decor situations. The manufacturer produce other ranges/hardware for more traditional rigging situations and uses so I’d take that as a fairly good indication that even the manufacturers think that gripples have a very narrow and specific intended use?

[empyfree]

I get it, I think we’re on the same wavelength it’s just that it’s hard to justify saying no to bosses, pm’s etc when they are correctly reading a spec and SWL.

[Seano]

If they fail under their SWL surely they’d be in court all the time?

 

A 5:1 or 8:1 factor of safety covers a multitude of sins. (And, to be fair, that is what a 'factor of safety' is actually for.)

 

when they are correctly reading a spec and SWL.

 

The manufacturer gives them a SWL for the purpose of what they're designed to do - hang HVAC or whatever, once.

 

Their SWL doesn't, as far as I can make out from the specs here incorporate any kind of a mode factor for the different means of making off the steel.

 

http://www.deepsoup.f2s.com/BR/gripplechoke.png

 

A soft-eye steel choked around a beam or purlin as recommended there would definitely *not* be considered good practice in our world. Soft-eyes in steels are generally not considered appropriate these days, in part because they lend themselves to this kind of abuse. At best I'd expect it to significantly degrade the SWL as compared to that achieved in other 'modes'.

 

I mention this by way of illustration that the SWL given to a thing by the manufacturer for one purpose does not necessarily mean it applies when you use it for something else entirely.

 

That 'once', above, may be important too. The SWL given is also given for a *brand new* gripple and rope, with a little rope being pulled through to adjust that one time and then that's it. Next time you use the same Gripple, all bets are off - the SWL in the literature does *not* apply to a second-hand device or rope.

 

This has occasionally been an issue with bullets in the past. They too were originally designed as a 'fit and forget' single-use device, but were pressed into use (and re-use) in our industry. The jaws wear over time, the bits that are meant to be lubricated get sticky, the bits that are meant to stick get slippery and galvanised ropes being pulled through repeatedly also has a tendency to gunge them up with zinc.

 

Any slippage under full load will greatly accelerate that wear and quite likely lead to immediate failure. I don't know of any serious accidents that have resulted, but there have certainly been near misses.

 

Happily they too are generally used for lightweight scenic elements only, and they too are gradually being pushed out now by the mighty Reutlinger. (Far superior in price as well as performance, unfortunately, but in this case you do get what you pay for.)

[ontoprigger]

I would look at getting steels made to just short of the required length and use short lengths of long link chain (STAC chain) to trim. The amount of adjustment on hanging these trusses will be within what you can get on that type of set up, but worst case use a combination of stac chain one end and a rigging screw the other.

[sunray]

I have been reminded that we put a stand in NEC [something like - leisure show] in the mid 90's, truss rig 10x6x5m high plus a 3m diameter x 1.5m high infilled with a white screen on top.

 

One of the other nightclub install companies had a similar sized truss box almost completely enclosed with black drapes hanging on 50mm tubes suspended at each end by Gripples.

 

During the event someone fell against the drape causing a Gripple to slip, bringing the whole drape down but leaving the tube hanging from one end.NEC H&S immediately closed the stand down for the rest of the day to do a full inspection after hours.

[swenk]

Hi all

 

I have had a full set of 5m, 5mm steels made up thimble to bare ends. from flints

 

also bought a complete set of type 50 reutlingers.

 

25 of each for sale after the event!

 

 

 

I'm convinced for the ladder truss with three led par cans on, three large gripples would have been fine, but it's best not to find out.

 

swen

[sandall]

Met a new use for gripples while out enjoying the sunshine today. A landscaped green area surrounding a new housing development, with a grove of recently planted mature trees. Presumably they had all started leaning down-wind, as every tree is now pulled upright by between 3 & 5 steel ropes, each terminated at the bottom with a gripple, apparently doubling as a bottle-screw for re-tensioning. Probably not covered by the manufacturer's spec, but quite a neat idea.

[ImagineerTom]

That is what gripples were originally invented for- Fence tensioning and agricultural lattice / trellace.

[sandall]

In that case it's good to see it being used correctly, rather than for dangling heavy things over people's heads.