US Patent 7291002 Apparatus and methods for 3D printing

The invention relates to apparatus and methods for producing three-dimensional objects and auxiliary systems used in conjunction with the aforementioned apparatus and methods. The apparatus and methods involve continuously printing radially about a circular and/or rotating build table using multiple printheads. The apparatus and methods also include optionally using multiple build tables. The auxiliary systems relate to build material supply printhead cleaning diagnostics, and monitoring operation of the apparatus.