US Patent 11470772 Balanced housing construction for flexible line trimmer head

A housing having a rotary axis and configured to support at least one radially projecting cutting component that effects cutting as the housing is turned around the rotary axis. The housing has a first housing part with a first wall and a plurality of discrete circumferentially spaced cavities in the first wall and each having a volume. The volumes of at least a first and second of the cavities respectively at first and second locations are different and strategically selected to cause a mass distribution on the housing that contributes to improved dynamic balancing of the housing as the housing is turned around the rotary axis.