I have a little post on stepper wiring here: [
ebldc.com]
I don't think I cover 8 wire steppers, but if you look at the 4 and the 6 wire configurations you will understand most of it. Basically, you have access to the 4 windings. Most of the stepper drivers out there will be for bipolar, so it is your choice whether you will want to wire them in parallel or in series. What do you get?
In parallel, the inductance and the motor resistance is reduced. Hence, you can move faster, but you loose some torque.
In series, your resistance and your inductance increase, so you will get more torque but will not be able to move as fast.
I imagine for an eggbot, either is fine. If it were something like a CNC router, I would recommend the series connection as you would prefer torque to speed.
PS A cool thing you can do with an 8 wire stepper is to use one winding for power and another winding for a sensor (something almost like a resolver). If done properly it can transform the stepper into a servo. That is way easier said than done, though. Just thought mentioning as it is a cool application.
JIQ
