Powder distribution system for three-dimensional printer

The present invention relates to apparatuses for distributing build powder in powder-layer three-dimensional printers (2) and for the collection of particulates of the build powder that have become suspended in the gaseous atmosphere in the vicinity of the build platform of the three-dimensional printer. These apparatuses include recoaters (20) that are particularly useful in providing uniform distribution of fine build powder across the width of the build platform or powder bed. The present invention also includes powder-layer three-dimensional printers (2) which comprise such apparatuses for distributing build powder and/or apparatuses for collecting such suspended particulates. The improved fine powder recoater (20) uses an ultrasonic transducer (30) to move powder through a sheet screen (28). The sheet screen (28) may be presented to the powder fed onto it in a narrow dispensing slot to limit the flow rate of powder from the dispenser and to provide control over the amount of powder dispensed. The width of the slot may extend to cover the entire build box fill zone. The ultrasonic transducer (30) is preferably adapted to periodically sweep through a range of frequencies during operation. The ultrasonic vibration system may be augmented with a low frequency vibration system. The dust collection system (160) draws air from the perimeter of the build box (172) down through the deck plate (170) of the printer (2) and out of the printer's housing (164) to an external dust collector (250).