I've finished the first two CNC lathe exercises. Actually, it's not a CNC lathe but a slant bed horizontal turning center. In theory it's similar to a manual engine lathe but in practice, not so much. The tooling all comes in from the back of the part rather than the front so the cutting bits are all upside down. Also, the tools are all mounted in a turret. The clearances are pretty tight between the tooling and the chuck. It would be pretty easy to crash a long drill bit into the chuck or the back of the machine if you weren't careful. Once the part is up and running the coolant prevents you from seeing what's going on, so it's pretty much an act of faith at that point. There's a graphic mode to dry run the part to give you a basic idea of tool paths and you can run it in single block, meaning you run one line of code at a time, to slow things down and he has us all keep all rapid machine movements at 5% of what the machine is capable of doing. There's still plenty of ways to screw up, however.
I don't know if I'll ever run a CNC machine again but I'd like to be able to. I've really been enjoying myself in the class. Need one of those Maker Spaces or Tech Shops around here. That'd be big time fun.