Sewing method and apparatus to increase 3D object strength

An apparatus for bonding printed composite layers into bundles during composite based additive manufacturing, comprising:

• a bundle convey subsystem having a piling station configured to receive and stack a plurality of printed substrate layers in succession from an additive manufacturing device in aligned formation as a bundle of the printed substrate layers, each printed substrate layer having a substrate sheet printed with a polymer, the bundle of printed substrate layers being a part of a stack of the printed substrate sheets forming a 3D composite object;
• and
• a sewing machine proximate the bundle convey subsystem, the bundle convey subsystem configured to transfer the bundle of printed substrate layers to the sewing machine, the sewing machine configured to sew the printed substrate layers together as a sewn bundle, the bundle convey subsystem further configured to transfer the sewn bundle to a stacker subsystem for subsequent bonding of the sewn bundle with a second sewn bundle to form a stack of printed substrate layers including the sewn bundle,
• the sewing machine including a sewing mechanism above the bundle of printed substrate layers and a looping mechanism below the bundle of printed substrate layers, the sewing mechanism including a sewing needle having a sewing thread attached thereto, the sewing mechanism configured to repeatedly pass the sewing needle through the bundle of printed substrate layers to pull a first loop of the sewing thread from one side of the bundle of printed substrate layers to the opposite side of the bundle of printed substrate layers, the looping mechanism configured to repeatedly wrap the first loop of the sewing thread around one of a second sewing thread and a second loop of the sewing thread, the sewing mechanism further configured to pull the sewing needle and attached sewing thread out of the bundle of printed substrate layers.