US Patent 10449718 Powder-layer three-dimensional printer with smoothing device

A powder layer smoothing devices adapted for use with powder-layer three-dimensional printers are described. The smoothing devices include a counter rotating roller having a complex powder engaging face that may include a series or plurality of flutes or may include knurling extending along at least a portion of the roller along the rotational axis. The smoothing device may also include a vertically adjustable finishing roller to follow the counter rotating roller across the build box of the powder-layer three-dimensional printer.