Tap tolerance range

6H Standard tap tolerance (ISO 2) allowing a medium fit between screw and nut; a lower tolerance (ISO 1) gives a close fit with no clearance on the sides between the screw and the nut, on the contrary, a higher tolerance, 6G (ISO 3) gives a coarse fit with high clearance, the latter is used if the part is coated or hardened or if a custom fit is preferred at the time of machining.

6HX – 6GX The letter X connotes that the tolerance is outside the manufacturing standard and that it is suitable for working with abrasive or resistant materials such as cast iron. By using a higher tolerance, the useful life of the tool is prolonged.