A printhead is provided for an inkjet printer. The printhead includes a wafer assembly defining a plurality of spaced apart groups of ink supply channels and a plurality of groups of ink ejection nozzle arrangements in fluid communication with respective ink supply channel groups. Each ink ejection nozzle arrangement includes a nozzle chamber structure mounted to the wafer assembly. Each ink ejection nozzle arrangement also defines a nozzle chamber for receiving ink from an ink supply channel and a nozzle rim through which ink in the nozzle chamber can be ejected. An anchor extends from the wafer assembly in a location external to the nozzle chamber. An elongate thermal actuator mechanism extends from the anchor and into the nozzle chamber.