What are recommended maximum speeds (rpm and m/s) for Cutting Discs? Size of Disc Maximum RPMs 2”, 50mm 30,650rpm 2.5”, 60mm 30,650rpm 3”, 75mm 20,150rpm 4”, 100mm 15,200rpm 4.5”, 115mm 13,600rpm 5”, 125mm 12,250rpm 7”, 180mm 8,500rpm 9”, 230mm 6,500rpm 14”, 350mm 4,400rpm What does INOX mean ? What material can I use a Cutting Disc on?