Metering build material in three-dimensional (3D) printing using a tool

An apparatus of a three-dimensional binder jet printer for metering flow of a metal powder, the apparatus comprising:

• a hopper including a plurality of walls defining an upstream opening, a downstream opening, and a flow path therebetween;
• a roller positioned downstream of the downstream opening and spaced apart from the hopper so as to form a gap between the downstream opening and the roller, wherein, when the hopper contains the metal powder, a height of the gap is configured to facilitate flow and metering of the metal powder out of the downstream opening, underneath a first wall of the plurality of walls of the hopper, and directly onto the roller only when the roller is rotating;
• and
• a tool configured to engage the roller.

An apparatus of a three-dimensional binder jet printer for metering flow of a metal powder, the metering apparatus comprising:

• a hopper having a plurality of walls and defining a downstream opening, wherein at least two of the plurality of walls are parallel to one another;
• a roller positioned downstream of the downstream opening in a vertical direction and spaced apart from the hopper so as to define a gap between the downstream opening and the roller, wherein the downstream opening faces the roller, and wherein, when the hopper contains the metal powder, a height of the gap is such that rotation of the roller is configured to facilitate flow and metering of the metal powder out of the downstream opening and underneath a first wall of the plurality of walls of the hopper, and ceasing rotation of the roller is configured to inhibit flow of the metal powder out of the downstream opening and underneath the first wall;
• and
• a tool configured to engage the roller.