Filament drive mechanism for use in extrusion-based digital manufacturing systems

A filament drive mechanism for use in an extrusion-based digital manufacturing system, the filament drive assembly comprising:

• a support component configured to be secured to an extrusion head of the extrusion-based digital manufacturing system;
• a first rotatable component retained by the support component with a fixed rotational axis;
• a second rotatable component retained by the support component, and comprising an axis of rotation and a central hole aligned with the axis of rotation, the central hole being defined at least in part by an internally-threaded surface, wherein the second rotatable component is biased in a first direction toward the first rotatable component, the first direction being perpendicular to the axis of rotation;
• and
• a filament tube configured to receive a filament strand, wherein the filament tube extends through the central hole of the second rotatable component, and comprises a sidewall port disposed adjacent to the internally-threaded surface, and wherein the biasing of the second rotatable component in the first direction is configured to engage the internally-threaded surface with the received filament strand within the sidewall port.

A method for building a three-dimensional object with a filament drive mechanism of an extrusion-based digital manufacturing system, the method comprising:

• providing a rotatable component of the filament drive mechanism, the rotatable component comprising an axis of rotation and a central hole with the axis of rotation, the central hole being defined at least in part by an internally-threaded surface;
• providing a filament tube, wherein the internally-threaded surface is positioned around the filament tube such that the internally-threaded surface is disposed at a sidewall port of the filament tube;
• biasing the rotatable component in a first direction that is perpendicular to the axis of rotation to contact the internally-threaded surface with the filament tube at the sidewall port;
• biasing the rotatable component in a second direction that is substantially opposite of the first direction, thereby substantially aligning the internally-threaded surface with the filament tube;
• loading a filament strand into the filament tube such that the filament strand extends through the central hole of the rotatable component while the rotatable component is biased in the second direction;
• removing the bias on the rotatable component in the second direction to move the rotatable component in the first direction to engage the internally-threaded surface with the filament strand;
• and
• rotating the rotatable component to drive the filament strand through the filament tube in a direction along the axis of rotation.