Back when I worked for Kurt over at KC Sound we used to get high flex cables all the time. Usually for sound snakes.
I need to find a source for a decent quantity (500' rolls would be ok) 4 and
2 conductor conductor shielded high flex. 16 ga would be ok for some and 18 ok for others. I could use 16ga for everything, but its hard to fit in the connectors on some controllers, and I prefer to save my fights where I can. I've been doing the CNC machining thing for a while, and now I am building some of my own machines from the ground up. In addition to using drag chains to limit flex and the type of flex, I would like to use high flex cable for servo motors that move with the machine, and for the 3 phase VFD driven spindles that moves on certain types of machines. Since they will often HAVE TO be bundled with encoder and other signal cables shielding is a big deal. (star grounded of course) The encoder and signal cables will all be shielded and grounded, but I like to cover my bases. I prefer to spend my time testing the machine concepts rather than chasing 100% preventable signal noise problems.Amazingly the inexpensive orange extension cords you can buy at the hardware store are pretty high flex, and in testing hold up modestly well. Unfortunately they are not 4 conductor (UVW G) or shielded.
Yes, I know regular stranded shielded will last for a long time, but I am aspiring for 30 year life with only failed components needing replacement over time. One of the big mills in my shop was made in 1982. I retrofit it with all new controls, but all of the servo power wire is the original stuff (as are the servo motors themselves). I ran new encoder wire, but only because I ran new encoders.