Straightening heavy coil spring can be a pain, especially if you don't have a forge big enough to heat the whole thing all at once and a tractor or forklift to pull it straight. I've tried working in sections on the anvil, with a bending fork, or using the hardy hole itself as a bending fork. All of these work, but they're awkward.  I was thinking about this the other day, when it occurred to me that uncoiling into some kind of jig could be an interesting possibility. And here it is: