What software are you using to drive the machine? The new DeskCNC has gerber and exelon tool pathing and drilling built in so you don't evern need to convert it to a dxf in the first place, just get the track and apeture file *.pcb straight ouf of your pcb development software eg:Protel and go for it, the cam wizard in DeskCNC lets you put in the tool dia for contour offset, great stuff, it also has a background tool change function so if you command T1 M06 it reads a file called toolchange.cfg and executes the lines of code the user puts, every one above has said all of the right stuff, it is just that you ony need to put it once and then it is stored until you change it, you can even write in functions for doing an automatic tool change later on down the track. Wait and watch DeskCNC, big things happening there.
