Do you know what 7:24 in BT knife handle represents when dealing with knife handles every day? The tool holder is the connecting body between the machine tool and the cutting tool. It is a key link that affects concentricity and dynamic balance, and should not be treated as a general component. Concentricity can determine whether the cutting amount of each cutting edge of the tool is uniform when it rotates once; Dynamic imbalance during spindle rotation will generate periodic vibrations.