The microstructures of a low carbon steel, an aluminum alloy, and a brass alloy were studied for input to highly theoretical mathematical models of machining operations. This was accomplished through production and analysis of samples of the actual pieces of each alloy which were to be machined. The microstructural content of each sample was analyzed through the use of a light microscope as well as a scanning electron microscope. The microstructure of the low carbon steel was found to display some processing defects through lack of a random distribution of microstructures. Thus this alloy, in this condition, was determined not to be ideal for input to these mathematical models. The microstructures of both the aluminum and the brass alloys were found to be extremely homogeneous. Thus upon input, these alloys we well would not introduce a random aspect to these models.