bb99: Thank you! The uprights on the machine which form the supports for both axes (bobbin and laydown carriage) are 2.5" apart. Those little motors are gutsy for their size. I remember (this was about 1999) going through a big box of 5.25" drives at a PC store and buying about 5 for maybe $3 each. There were a number of different steppers in them, some good for this type of project, some not so good. These are 1.8 degree unipolar steppers. Some of the disk drives had steppers which were integrated with their leadscrew device and weren't suitable.
HuFlung, the wire is enamel coated, 44 guage, 0.0026" dia. It is insulated, but the trick with the coils is that each LAYER of winds must be insulated from the others. The coils generate about 20 kV, with a steadily increasing potential from one end to the other. The thing to avoid was allowing the last few turns to arc between layers to the first few turns, as 20,000V will jump a big gap, and once even one arc occurs inside, it leaves behind a trail of carbon, which conducts, making subsequent arcs automatic.
Here is a source of magnet wire online:
http://www.planetengineers.com/defau...Wire%2C+Magnet
Get this, the 54 guage copper is so fine that 1 pound will unwind to a length of 156 miles!
If anyone else is interested, get Bob Shores's wonderful book "Ignition Coils and Magnetos in Miniature. Bob is an older, ultra talented gentleman who has plans for a number of sweet little engines, which I noticed a few of the guys are working on. His book is worth every penny, as it has great info not only on coils, but on ignition circuits and methods for small engines.
Here is one last pic, showing a finished coil potted into a delrin tube. These coils can also be mounted in a wax filled box (like a model T coil) for a cool scale appearance next to a small farm or hit and miss engine.
If I can find some thin liquid insulating enamel, I'd like to resurrect this device and crank out some more. Maybe there's a market for them, as the coils you can rip off from a wrecked 2-stroke garden tool almost always have electronics potted inside, and they aren't suitable for a straight CDI or kettering ignition for our small engines.