I do it all by hand with the help of an arrow wrench or two. I usually work at our kitchen gas stove. I think one secret about straightening shoots or cane is not try to straighten the whole thing at once. Take the worst bends first(unless they are next to each other) heat and straighten then lay shoot down on a flat surface until cool. Then go back and do the same on the next worst and so on. I sometimes let shoots cool over night before straightening more. If the wood is still warm it doesn't take much force to rebend the wood back to where you started.
Once I have the shoot straight I'll start at one end and heat and rotate the shoot, moving from one end to another. With hardwood shoots(sourwood for me) this is when I add color from the heat. Heat the shoot well and keep moving to the far end. Be aware of any steam that might come out of the far end. It will scald you!
Once you complete this "tempering" make sure the shoot is straight then lay it flat until cold. The tempering helps to keep the shaft straight.
I usually have cut my shoots to final length by the time I temoer them.
I do sometimes use arrow wrenchs, all home made and pretty simple, for difficult bends but mostly I use my hands(use heat protection) and eyes.
ps, I don't build sets either. I will straighten a few shafts at a time but each arrow is made as a set of one for me.
