Mill files can be used on tools where fast metal removal is required. The 10" mill file works great on lawnmower blades, shovels, and other large garden tools. The 8" mill file gives a slightly smoother surface that is more suitable for smaller axes and the initial edge on a woodworking scraper.
Selecting a mill file can be confusing. If you understand the basic terminology, it is actually quite simple. Mill files have different cuts that determine its coarseness. The coarsest is the bastard cut. The middle is called the second cut. The finest is called a smooth cut. In addition to cut, the size also determines its coarseness. Within the same cut rating, the longer the file, the coarser the file becomes. For example, our 10" second cut mill file is coarser than our 8" second cut mill file.