Amazing!! i was confused how to make a spring, though mine is a little bigger about 100 mm in diameter i hope this mechanism will help me. Thank you MR.
It looks like the spacing of your spring coils is based just on your hand-eye coordination. I don't see any feed mechanism other than that. So if you are pretty good at controlling that, you get a nice even spacing, but if not, then the spacing will be irregular, correct?
If you haven't found a solution, look into cams. You could have a cam that is thin on one section and wide farther down that moves from thin to wide as the bar progresses.