The duties of a knife grinder are to sharpen, straighten, and smooth knives, blades, and other parts for cutting equipment, such as deli slicers or scissors. Some knife grinders work at production or manufacturing facilities and have many of the same responsibilities as buffers and polishers. As a machine operator, you ensure machine set-up is done to specification, then you load, operate and unload machine cutters that are used to sharpen or construct knives and conduct numerous quality assurance duties, such as testing the durability or sharpness of your products.