As we promised, today we are talking again about rigging. This time we tell you some points to be taken into account such as the right way to keep a motor or to measure the final position of an equipment.
- Falls and blows of metal equipment
You must never hit any metal item with something hard or metallic. You can generate internal cracks impossible to detect without an X-ray machine and it might break with infinitely less load that its specifications. The same applies when dropped from a certain height.
- Shapes and working angles
It must work freely without stumbling or being forced with or against anything, for example, do not hold a shackle on a beam or do not put an electrical chain hoist working held on a diagonal of a truss.
About working angles, do not exceed 90º in slin knots or Vs to do.
Any item that does not show W.L.L. should not be used for lifting or suspension.
For example, some clamps do not show W.L.L. so they cannot be used to lift or suspend loads, it can only be used for lashing.
- Working with electrical chain hoists
All electrical chain hoists that are used during a performance, at least each section (sound, lighting, video, rigging, etc.), have to move in the same direction when the controls are to the same direction. It is not allowed that some ones go up and others go down. We think that marking the control with tape and marking the tape with the invested ones is enough but this is a very dangerous and widespread misuse in many companies. To avoid this, it is better to test the electrical chain hoists, cables and controllers in the warehouse and when we push the controller in one direction, the electrical chain hoist will move in that direction regardless of which electrical chain hoist, chain or output controller we are using.
When using multiple electrical chain hoists with a load is quite possible that some of them carry more weight than others. For example, in the center there is a straight truss or a truss that has the landing wiring, this will cause any differences in speed between them, so it is appropriate to adjust every few meters the height of the motors to avoid forcing or bending the truss.
The best way to set a truss horizontally when working at height without using load cells is with a laser level or a plumb line and with a laser level to measure next to the sling knot of each motor. An alternative method is to put a tape measure in each slinging and then measure taking care that the tape is in a vertical position. Thus, we will have the truss straight and it will not suffer and the loads calculated will be the same and we will not overload any structural element where our electrical chain hoists are hung up.
When the body of the electrical chain hoists is in the flight case and the branches of the chain do not have tension, help them to get in and out giving the needed tension to avoid pinching the chain and generate unnecessary wear on the chain guides.
When we use for lifting Line Array, each electrical chain hoist must be able to withstand 100% of the weight of the entire Line Array during up and down maneuvers. To provide the right acoustic angle we always need to pull more from one than the other so one of them ends up taking almost all of the weight.
And last but not least, try not to tip over the motor’s flight cases during transportation to avoid it from damaging and hitting.
Bibliography: AFIAL. Beginner's Guide to Rigging in the entertainment industry. Pablo Moreno