Provided is a printer having a printhead assembly which includes an elongate support beam. The support beam includes a silicon core, an intermediate elastomeric layer mounted to the core and an outer support structure mounted to the elastomeric layer, as well as a plurality of printhead modules mounted to the support beam. The printhead modules and support beam are configured so that the printhead modules are misaligned when the printhead assembly is at a room temperature and move into alignment when the printhead assembly heats up to an operating temperature of the printhead. The printhead assembly also includes a number of fiducials located on the respective printhead modules to allow visual verification of such alignment.