flynz4me, The program McFueler is referring to is called Mach 3. It is a control program that takes g-code and translates it into step and direction pulses to essentally "drive" the machine. if you have a commercial cnc then you have a built in control (this is where all the buttons softkeys, mpg ect. are) and you should consult your manual for its capabilities. Yes you can scale in mastercam, I have not had a need for it yet so i cant give you more in depth information than that. Check out
www.cnczone.com they may have a better answer for you.