Bit accessory and bit assembly

A bit assembly, comprising:

• a bit with a head;
• and
• a bit accessory;
• wherein the bit accessory comprises:
• a sleeve with an accommodating cavity running through the sleeve;
• a limiting member removably attached to the sleeve, the limiting member defining a limiting hole shaped to mate with at least a part of the head so as to limit the length of the bit passing through the sleeve;
• an installing casing for elastically sleeving over an outer periphery of the bit wherein the installing casing is at least partly accommodated in the accommodating cavity;
• and
• an end cap having an inserting hole with a hole diameter smaller than an outer diameter of the installing casing wherein the end cap is installed on a rear end of the sleeve,
• wherein the sleeve comprises:
• a first stopping portion for stopping the limiting member from passing through the accommodating cavity;
• wherein an inner wall of the limiting hole comprises:
• a first hole wall portion forming a first hole wall of the limiting hole and providing the limiting hole with a minimum hole diameter and a second hole wall portion forming a second hole wall of the limiting hole and providing the limiting hole with a maximum hole diameter;
• wherein the limiting member is at least partly accommodated in the accommodating cavity and a direction which the limiting hole runs through the limiting member is parallel to the accommodating cavity when the limiting member is stopped by the first stopping portion,
• wherein the thickness of the limiting member in the direction which the limiting hole runs through the limiting member is between 0.1 and 5 mm and the first hole wall portion and the second hole wall portion are arranged at the same position along the same direction which the limiting hole runs through the limiting member;
• wherein the first hole wall portion and the second hole wall portion are arranged alternatively along the circumferential of the direction which the limiting hole runs through the limiting member and the first hole wall portion protrudes from the second hole wall portion, and
• wherein the end cap includes a cover portion for covering a part of the accommodating cavity at the rear end of the sleeve and stopping the limiting member from moving out of the accommodating cavity from the rear end of the sleeve and a connecting portion threadably connected to the sleeve, and the installing casing and the limiting member can move out of the accommodating cavity from the rear end of the sleeve when the end cap is removed from the sleeve.