A trimmer head (10) for use in a flexible line rotary trimmer including a housing (14) adapted to be operatively connected to the trimmer to effect rotation of the head (10) and a spool (16) operatively connected to the housing (14) for rotation therewith. The spool (16) defines at least one inwardly extending line receptor channel (91), preferably formed by a plurality of inwardly tapered walls (93) so as to be polygonal in cross-section. So configured, the channel walls (93) will securely grip the cutting line (17) upon the line (17) being inserted in the channel (91) and wound about the spool. To provide uniform winding of the line (17), a plurality of cam (44), cam abutment and sliding surfaces (46) are operatively connected to the housing (14) and spool (16) such that when the spool (16) is manually rotated relative to the housing (14) in the drive direction, the spool (16) is caused to reciprocate axially within the housing (14) evenly distributing the line (17) about the body of the spool (16).
