Grinder with fast installable/detachable grinding disc

A grinder with fast installable/detachable grinding disc, comprising:

• a main body in which a driving device is installed;
• a rotary switch mounted on the main body and manually operable to change position of the rotary switch;
• a linking device mounted at bottom end of the main body and drivable by the rotary switch, whereby by means of operating the rotary switch, the linking device is driven to move between an expanded position and a closed position;
• a rotary shaft, bottom end of the rotary shaft being recessed to form a shaft hole, the rotary shaft being disposed at bottom end of the driving device and drivable by the driving device to rotate;
• and
• a detent mechanism mounted in the rotary shaft, the detent mechanism having at least one detent member which is displaceable along the radius of the rotary shaft, an inner end of the detent member being formed with an engaging section, whereby when operating the rotary switch to drive and move the linking device between the expanded position and the closed position, the detent member is displaced to move the engaging section into or out of the shaft hole of the rotary shaft.