Newbie questions about CNC workflow

[Neale]

I think that he already has LinuxCNC, although the web site refers to it under its old name, EMC2. Same thing but name changed due to trademark or some such issue a while ago.

You can develop gcode wherever you like. You can hand-write it, but most people use some kind of CAM package that takes a CAD drawing as input and gives gcode as output. It can be a bit more complicated than that, but that is the basic principle. As Lee says, your friend would then run LinuxCNC which takes the gcode file and turns it into actual motor control signals. Because the gcode is portable (pretty standard with minor variations depending on whether LinuxCNC or Mach3 or some other machine control package will read it - you tell the CAM package which flavour of gcode you want) then you don't have to run CAD or CAM or machine control on the same platform. Mix and match as you will. I use Windows for CAD and CAM but copy files over the network to my LinuxCNC/Ubuntu machine in the garage. That kind of thing is pretty standard practice.

That's a pretty high-level description. Someone will be able to fill in details if you would like to go down a level or two.