Hi
I needed a verrry soft spring. Math showed, that it has to be 5.5m long! ;-)
No, I'm kidding. For my heat treating furnace, I had to wind a new heating-element. It is basically a single "spring" that is laid in a zig-zag-pattern into grooves of the carrier. Overall length is 5.5m!
Now, how do you wind such a biest?
Like any normal spring. Wind it around a bar that is clamped in the three-jaw chuck. The bar is supported with a live centre. After one run of winding, just stick the spring through the spindle hole and clamp the bar together with the wire. More sooner than later, the spring will stick out on the left side of the spindle. I "constructed" (it was a hack) a guide out of some plastic-tube (used for electrical installation). Due to some good luck, I had moved my lathe around in the shop some months ago and had enough room for over 5m sticking out of the spindle. :-)
Worked really well that way!
Nick