A machinist is a skilled tradesperson who operates machine tools to produce precision parts and instruments. They use a variety of machines, such as lathes, milling machines, and grinders, to create the desired product. Machinists must have a good understanding of mathematics and mechanical principles in order to accurately operate the machines. The OPERATOR of a machine is responsible for setting up, operating, and maintaining the machine in order to produce the desired product. They must also be able to troubleshoot any problems that may arise during the operation of the machine.