I am completely beginner in the field and I ve just received my driving board and steppers from stepperworld and I am starting to build the frame for the router...
I ve one question still without answer...
how the program or board will know that one rotation of motor = X mm of displacement ot my X, Y or Z axis???
is there any setup to be done at some stage to make the correspondance between rotations of the motor and motion of gantry?
That's correct, those settings are in MACH2 or TURBOCNC. You have to create them and enter the numbers into the programs. The board doesn't know or care about the distance. It simply controls the steps.
Note: Each program sets up the rotation/movement differently. TURBOCNC was way easier to understand than MACH2. But once its done, you don't have to worry about it anymore.