>>16754961
Machinist here. diy used to have a machinist general but now its gone. you want this
-Imperial and metric systems.
-Basic geometry
-Trigonometry
and you won't use it most of the time. Engineers won't trust you and will avoid you touching anything as much as possible.
you should worry about using one of these (pic) and how you will tie the stock to the machine. tieing the stock to the machine will be your main trouble.