Abstract: In example implementations, a powder level sensor is provided. The powder level sensor includes a capacitive sensor, a processor, and a cleaning mechanism. The processor is communicatively coupled to the capacitive sensor. The processor interprets a measurement of the capacitive sensor to detect a layer of residual build material on a surface of the powder level sensor. The cleaning mechanism may be communicatively coupled to the processor. The processor activates the cleaning mechanism to remove the layer of residual build material on the surface of the powder level sensor.

Abstract: In an example implementation, a powder metering device to move powder in a 3D printing system includes a rotor comprising a central hub and peripheral wheel to rotate about a shaft. Compartments are formed between the hub and the wheel by a plurality of fins that emanate from the hub at first fin ends and affix to the wheel at second fin ends. A top and bottom disk each have a planar surface to lie flush against and to seal, respectively, top and bottom perimeters of each compartment as the compartments rotate about the shaft between a powder receiving position and a powder dispensing position.

Abstract: In example implementations, a powder level sensor is provided. The powder level sensor includes a capacitive sensor, a processor, and a cleaning mechanism. The processor is communicatively coupled to the capacitive sensor. The processor interprets a measurement of the capacitive sensor to detect a layer of residual build material on a surface of the powder level sensor. The cleaning mechanism may be communicatively coupled to the processor. The processor activates the cleaning mechanism to remove the layer of residual build material on the surface of the powder level sensor.

Abstract: A build device and a method of operating the build device are disclosed. In a method provided, a build material is directed to an intermediate vessel from a conveying line. The build material is separated from an air stream and dropped into the intermediate vessel. The intermediate vessel is emptied between a first build operation and a second build operation.

Abstract: According to examples, a 3D printing system may include a feed line to receive build material particles from a material bin, an air pressure generator to generate airflow inside the feedline to move the build material particles through the feedline, and a cyclone separator to receive the airflow and the build material particles from the feed line and to separate the build material particles from the airflow. The cyclone separator may include a chamber wall, a build material particle discharge opening, and a tapered wall connecting the chamber wall and the build material particle discharge opening. In addition, a ratio between a diameter of the chamber and a diameter of the discharge opening may be between about 1.5 and about 4.0.