Rotary trimmer having multiple rolling blades

A rotary trimmer having multiple rolling blades, the rotary trimmer comprising:

• a slider for traversing a rail, including a partition and a side cover, both connected to a top plate, wherein a blade holder recess is formed between the partition and the side cover;
• a blade holder, settled in the blade holder recess and having a portion formed as a rotating shaft which rotates about a rotational axis and is positioned between the partition and the side cover, wherein the rolling blades are settled on the blade holder and arranged around the rotating shaft of the blade holder with cutting edges thereof partially projecting from a periphery of the blade holder;
• said rolling blades rotate about axes which are parallel to said rotational axis;
• a knob, provided at an exterior of the side cover and having a driving shaft connected to the rotating shaft of the blade holder so as to drive the blade holder to rotate for shifting the rolling blade to be used to a predetermine position where the cutting edge of the rolling blade to be used partially projects from edges of the partition and the side cover;
• and at least one spring element and a plurality of positioning recesses formed on the side cover and the blade holder, respectively, so that the spring element can be alternatively combined with one said positioning recess;
• wherein the side cover has a receiving portion forming a channel perpendicular to said rotational axis and a latch settled in the receiving portion, in which the latch is shiftable in the receiving portion in a direction perpendicular to said rotational axis to be coupled with or separated from the knob;
• wherein the knob has a periphery provided with ports for being alternatively coupled with the latch.