M2 and M3 are types of HSS often found in these tools. Bi-metal hole saws will cut through wood, plastics, laminates, aluminum and even thin sheet steel. Tungsten carbide tip (TCT) and solid HSS hole saws are good for cutting thicker metal. Diamond hole saws are used for cutting glass, tile, concrete, granite, marble and other types of stone. Instead of teeth, these hole saws have a particle coating of silicon carbide (SiC), also known as carborundum – not diamond at all.