CPC B29C 64/245 (2017.08) [B29C 64/118 (2017.08); B29C 64/232 (2017.08); B33Y 30/00 (2014.12)] | 18 Claims |
1. A 3D printer comprising:
a heated build chamber comprising opposing side walls, each opposing side wall having a plurality of spaced apart slots; and
a platen assembly within the chamber, the platen assembly comprising:
a grid assembly comprising at least six independent beams forming at least a 4 ×2 framework of interlocked perpendicular x direction beams and y direction beams, providing a substantially planar upper surface and a lower surface, wherein the grid assembly comprises:
an interior grid comprising at least two x direction beams interconnected with at least two y direction beams; and
an exterior frame comprising exterior beams that at least partially surrounding the interior, wherein the exterior frame surrounds the interior grid; and
a platen comprising a metal sheet supported on the upper surface of the grid assembly and secured to the grid assembly such that the upper surface provides a substantially flat build surface;
wherein the x direction beams, the y direction beams and the platen are constructed of substantially a same material having substantially a-same thermal expansion properties; and
wherein the build surface of the platen has a build surface area of at least 400 square inches and maintains its flatness to within a flatness tolerance of 0.020 inches over a temperature range of at least 20C-300C.
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