I'd like to build a Pan/Tilt table for my rather heavy camcorder. The ones that seem popular for Arduino enthusiasts look to fragile to support the weight of my device so I bought some "generic" stepper mtors on ebay. They came without datasheets but I figure they are Bipolar models since they have 4 wires coming out of each one.
So I need to figure out what makes the motors go. Please point me to a layman's description of stepper motor theory. Also is it reasonable to expect my Arduino Uno to drive them or do I need some sort of controller circuit / chip to do that?
you most likely cannot drive steppers directly with arduino. look here Stepper - Arduino Reference for stepper drivers and library. That library will only drive one stepper but there are other libs for multiple motors. Wikipedia for stepper motors to see how they work. My favorite driver is the 754410 two wire.
You might get some pan/tilt ideas from the servocity products below. With heavy objects, the best construction is where the weight of the object is balanced in its holding mechanism such that the motor/servo does not have to hold the weight of the object.