Digital manufacturing system for printing three-dimensional objects on a rotating core

A three-dimensional printer comprising:

• a cylindrical member having an outer surface;
• a frame having a mechanism that is configured to move between a first mechanism position at which the mechanism engages the cylindrical member so the frame rotatably supports the cylindrical member and a second mechanism position at which the mechanism is spaced from the cylindrical member to enable transfer of the cylindrical member to and from the frame;
• a first printhead mounted on the frame to enable the first printhead to eject material onto the outer surface of the cylindrical member;
• a first driver operatively connected to the cylindrical member to rotate the outer surface past the first printhead;
• a second driver operatively connected the mechanism of the frame to move the frame between the first mechanism position and the second mechanism position;
• a third driver operatively connected to the first printhead, the third driver being configured to move the first printhead relative to the outer surface of the cylindrical member;
• a sensor configured to generate a signal indicative of a gap between the sensor and a layer of elected material most distant from the outer surface of the cylindrical member;
• and
• a controller operatively connected to the first printhead, the first driver, the second driver, the third driver, and the sensor, the controller being configured to:
• operate the first driver to rotate the cylindrical member;
• operate the first printhead to eject material onto the outer surface of the cylindrical member and build layers of material on the cylindrical member as the outer surface rotates past the first printhead;
• operate the second driver to move the mechanism of the frame between the first mechanism position and the second mechanism position selectively;
• operate the third driver to move the first printhead from a first printhead position to a second printhead position relative to the outer surface of the cylindrical member;
• identify a radial distance from an axis of the cylindrical member to the layer of elected material most distant from the outer surface of the cylindrical member with reference to the signal generated by the sensor;
• and
• operate the first driver to adjust rotation of the cylindrical member with reference to the identified radial distance to maintain a predetermined angular velocity at the layer of elected material most distant from the outer surface of the cylindrical member.