Longtime FF user myself using Sketchup for design and Simplify3D for slicing and gcode generation. I finally took the plunge and placed an order for a CNC router to enable me to make some things the FF isn't suitable for. If any 3ders here also have experience with CNC routers, I was hoping for a little discussion to help me wrap my head around the differences in how both machines build objects (or in the case of CNC...subtracts).

As far as I can gather from my research, gcode that is generated for a 3D printer isn't going to work on a CNC machine without some modification. I'm assuming this is due to the fact that a program like Simplify3D doesn't have inputs or settings for things like tool type or size. Not only that, but the toolpath is going to be a lot different because it has to move around an object that's already there (say a block of wood that's being carved) as opposed to 3D printing where there's nothing there at the start of the build.

One other question I had that I don't seem to find referenced anywhere in discussions concerning CNC machines concerns the original carving object size. I assume there has to be a way to tell the machine what you're starting with, but I can't find mention of this process so far. In other words, if I'm carving a 5 x 5 mm cube from a block of wood that is 10 x 10 mm, there must be a setting somewhere to tell the machine what I'm starting with?

Sorry for the off topic. I know I could post this on some CNC forum, but I thought it'd be easier to try here with other FF users first.