Cabling, or twisting as it is also called, is the process of bringing all the elements together to make a round and flexible cable.
It may seem a simple thing, but why are cables usually twisted and round, rather than flat? Does it make a difference if the cable twisting is very long or short? And what about the direction… does it really matter if the cores all turn the same way?
Why we cable things together
The best reason to make a cable round is to give it flexibility in all directions. Flat cables can be great, provided the cable will only flex in one direction. Flat cables have a much smaller “height” compared to the diameter of a round cable and this allows for a much smaller bend radius. The trouble is that while the height might be smaller, the “width” will be that much larger and bending the cable over the width axis becomes much, much harder. By cabling the elements into a round format, the cable gains the ability to flex evenly in all directions.
A stiff or springy cable?
It is the lay length (the distance a core travels lengthwise while it rotates 360o around the central point of a cable) that determines properties like flexibility. The shorter the lay length, the more the cable will behave like a coiled spring, able to bend easily in any direction. Short lay lengths also hold the cores together much better and are commonly used for unscreened and unjacketed cables. This comes at a cost, however, as it takes a lot longer to produce cables with a short lay length.
Running a long lay length allows production to run much faster but does result in a stiff cable and a reduced flex-life. Long lay lengths can have a beneficial effect on paired cables however; as pairs are better able to fit together, reducing the finished diameter.
Moving in the same direction – or not
When making a cable, it is important that the elements being twisted move in alternating directions to make the cable evenly balanced. Having everything rotate in the same direction will make the cable coil up on itself -which can be ideal if making a coiled cable that will spring back to shape. By giving each layer alternating left and right hand lays, we keep the cable from doing this, improving the cable’s ability to flex in all directions.