for a CNC router. Flatbed scanners don't have much resistance to deal with, so they can use fairly small, weak motors. A router has to push a heavy gantry, change directions frequently, and counter strong cutting forces, so they need something pretty powerful. You can gear motors down to get more torque, but then you lose speed, which isn't that good in the first place with steppers.
If you're looking for simple and effective drivers, I doubt that starting with a chip like an Arduino and rolling your own is going to fit the bill. You're much better off getting drivers designed for CNC that are known to work. Of course, if you're an electronics engineer getting into this in order to learn how to design CNC drivers, I'm sure you'll have an interesting learning experience.
If you're building your machine from scratch, then getting the mechanical assembly, with all the slides and screws built first and then shopping for motors and drivers would make sense; you'll have a better idea of the torque required to make it move. Once you've got a working machine, then you can start trying out demos of CAM systems - since they're generally time-limited, you can see what works for you before having to pay.
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