Patent ID: 7008209

Claim:
A three-dimensional printing machine comprising: a powder presenter configured to repeatedly present a supply of powder; a build bed assembly configured to receive sequential layers of powder for building a product, the powder presenter and the build bed assembly being aligned in a working direction; and a roller assembly comprising: an elongated roller configured to spread powder from the powder presenter to the build bed assembly; and a pair of sliders coupled to the roller assembly and projecting from the roller assembly in the working direction, the sliders being spaced apart from each other by a distance selected to prevent powder from escaping laterally from the build bed assembly as the powder is spread from the powder presenter to the build bed assembly; wherein the roller assembly is mounted to a carriage structure and the pair of sliders is slidably mounted to the roller assembly such that the sliders can move vertically with respect to the three-dimensional printing machine, and further comprising a biasing member urging the sliders downward.