Many years ago I was talking with an older gentleman, my father, about the possibilities of firearms confiscations.. He replied that he was a machinist and he could make his own guns if he needed to. This would also apply to any other machine that broke down, including the lath or mill themselves. The abilities to repair or make what ever you need is the hallmark of self reliance, irregardless if it's food, water or bullets..
Here is part one of the seven part course on machining.
Military Manuals Army Machinist Course -1988- Part one of seven-Milling Machine 2015-05-17
The Army course on Machining and machine metal work.