I'm in the design stage for my own 48"x48" CNC machine. I would like to use my CNC machine for working wood, plastic, aluminum, and do PCB milling. Due to limited space, I have chosen to use a moving gantry for all three major axises.
Looking over some of the designs I have seen on CNCzone, I notice some use belt driven X and Y axises. A belt driven solution, on first glance, appears to be considerably cheaper than a lead screws or ballscrew solution - as much as a third of the cost of the others.
What are the pro and cons to using belt driven? Do they stretch while in use, or deform over time? How does accuracy compare to threaded solutions?
With a belt solution, what considerations should one use for selecting components?
With a belt it looks like it's easier to implement a dual drive system for the X axis which carries the full load. Any comments about the good and bad of this idea?