Re: naive question from a noob
Buying used equipment does require some care, but I have only one machine in my shop that I bought new. The rest were like new mechanically, but required a controls upgrade. Buying used equipment from eBay is some risk, but sellers are generally honest. It is certainly best if you can physically look at a machine before purchase, something I have done in all cases. In most cases a quality CNC mill will be in mechanically pretty good shape even after years of use as long as it has been properly lubricated through its life. An old manual Bridgeport will generally have more wear than the same year CNC machine, just due to the difference in maintenance.
From Fusion 360 to the mill is no problem. Fusion 360 has built in CAM and that is where you develop your tool paths, then it just a matter of post processing to create the G code using the machine/control specific post processor that is included in Fusion. This process is the same for all machines.
All machines will require some setup and there is a learning curve. But it's not that difficult.
Absolutely there is a difference between a machine designed for wood cutting and one designed for metal cutting. In general for a given work envelope the metal working machines are much more riigid and maybe at least 5x the mass of the woodworking machine. Also the woodworking machines have much higher spindle speeds and generally feed faster than the metal working machines. Having said that, metalworking machines will cut wood just fine, they just run a bit slower.
Jim Dawson
Sandy, Oregon, USA