3D printer with head carriage with filament cutter and removable print head

An extrusion-based 3D printer configured to print 3D parts in a layer-by-layer manner, the 3D printer comprising:

• a platen configured to accept and support extruded material;
• at least one print head configured to extrude material to print a 3D part;
• a gantry configured to move the at least one print head as the material is extruded;
• and
• at least one head carriage configured to engage the at least one print head, the at least one carriage comprising:
• a head carriage receptacle configured to accept the at least one print head;
• an actuating lever positionable between a first, clamped position wherein the print head is substantially fixedly retained to the head carriage receptacle and a second, unclamped position wherein the actuating lever disengages the print head from the print head receptacle;
• and
• a filament cutter positioned above the at least one print head and configured for actuation by a user while the printer is in a paused or off state, wherein the filament cutter comprises:
• a blade comprising a through bore having an exit surface, wherein the through bore comprises a first diameter at the exit surface;
• a fixed surface aligned with the exit surface of the through bore;
• and
• a mechanism configured to be moved by the user such that the blade is positionable between a first, non-cutting position where filament can be fed to the at least one print head through the through bore in the blade and a second, cutting position wherein the filament is cut above the print by moving the blade relative to the fixed surface, wherein as the blade is moved to the second, cutting position, a scissors cutting action is generated between the exit surface and the fixed surface.