Patent ID: 8419996

Claim:
A print head assembly for use in a fused deposition modeling system, the print head assembly comprising: a carriage frame configured to be retained by a gantry mechanism of the fused deposition modeling system; a control board secured to the carriage frame; a receptacle for use with a removable print head having a cartridge assembly, a motor gear disposed within the cartridge assembly, and a filament drive mechanism, wherein the receptacle comprises: a base portion supported from the carriage frame and configured to receive the cartridge assembly of the removable print head, wherein the base portion comprises an alignment feature configured to engage with a reciprocal alignment feature of the received cartridge assembly; and a lid configured to close against the base portion to retain the received cartridge assembly at least partially within the receptacle; and a rotary encoder retained by the control board, the rotary encoder being configured to measure rotations of the motor gear through the cartridge assembly while the cartridge assembly is retained by the receptacle.