Abstract: A system and method for calibrating the gap between a 3D printer extruder nozzle and build platform are disclosed. To calibrate, the build platform is moved laterally in the horizontal plane and the extruder nozzle is moved downward toward the build platform. While moving the nozzle downward, the velocity of the build platform or the power required to move the build platform in the horizontal plane is monitored. A drop in velocity or an increase is power required to move the build platform is detected when the extruder nozzle contacts the build platform due to kinetic friction. The vertical height of the extruder nozzle is then set or calibrated relative to the build platform based on the position of the extruder nozzle when the contact was detected.

Abstract: A positioning mechanism for precisely moving a 3D printing stage in two dimensions is disclosed. The positioning mechanism consists of a first drive assembly, a second drive assembly, a moveable platform, and a stationary frame. The first and second drive assemblies each consist of a gear rack, pinion wire, and actuator. The first and second drive assemblies are configured to move the stage in orthogonal directions in a substantially horizontal plane. Both the first and second pinion wires are in direct contact with the stage as well as the frame, thereby providing an effective parallel linkage between stage and frame.