Abstract: Methods of preparing a particulate build material for three-dimensional printing can include loading fresh particulate build material including from about 80 wt % to 100 wt % fresh metal particles into a mechanical mixer, and mechanically conditioning the fresh particulate build material to generate conditioned particulate build material including conditioned metal particles. The fresh metal particles can have a surface oxide layer, and the fresh particulate build material can have a particle size distribution with a D10 particle size from about 2 ?m to about 10 ?m, a D50 particle size from about 5 ?m to about 20 ?m, and a D90 particle size from about 20 ?m to about 40 ?m. The conditioned particulate build material can include a modified cohesive index (compared to the fresh conditioned particulate build material) ranging from about 25 cohesive index units to about 35 cohesive index units.

Abstract: A varying a composition of build material used for a three dimensional (3D) part formed by a 3D printer are disclosed. In a system provided, a number of vessels for build material are included, wherein each vessel includes a feeder coupled to a conveying system. The conveying system conveys and blends build material from the vessels. A controller is configured to adjust a composition of the build material by adjusting an amount of material added from each of the vessels by controlling the feeder on each of the vessels.

Abstract: A 3D printer is disclosed herein. The 3D printer comprises a build material distributor to generate layers of a build material in a spreading direction along a spreading axis; a resonator mounted on the build material distributor to vibrate the build material distributor along the spreading axis at a frequency; and a controller. The controller is to control the resonator to vibrate the build material distributor at the frequency while controlling the build material distributor to spread a volume of build material over a platform to generate a layer of build material.

Abstract: Example implementations relate to different mixtures of build materials deliverable during a three dimensional (3D) print operation. In some examples, a 3D print apparatus may include a delivery hopper to deliver build material to a print zone of the 3D print apparatus and a plurality of build material hoppers to which the delivery hopper is connected for receipt of at least one of a corresponding plurality of build materials. A controller of the 3D print apparatus may direct that variable proportions of a first build material relative to a second build material are receivable by the delivery hopper from the plurality of build material hoppers during the 3D print operation, where different mixtures of the variable proportions of the first build material and the second build material are deliverable to the delivery hopper during the 3D print operation.

Abstract: An example of an apparatus is provided. The apparatus includes a build material transport path to transport a build material with air flow. The apparatus includes a humidifying element to receive the air flow and to add moisture to the air flow. The apparatus includes an inlet to introduce ambient air into the build material transport path to decrease moisture content in the air flow. The apparatus includes a valve to connect the humidifying element and the inlet to the build material transport path. The valve is to adjust an amount of ambient air introduced into the build material transport path. The apparatus includes a sensor to detect the moisture content in the air flow and to generate a signal to indicate the moisture content. The apparatus includes a processor to receive the signal to control the valve to maintain a moisture content in the air flow.

Abstract: In some examples, a method includes applying a negative pressure to a gas-filled volume through a vent. While a pressure in the volume decreases, the method draws a gas out through the vent and moves a liquid into the volume. The volume is filled with the liquid so that one side of the vent is covered with the liquid and the pressure in the volume increases up to a specified point.

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: A varying a composition of build material used for a three dimensional (3D) part formed by a 3D printer are disclosed. In a system provided, a number of vessels for build material are included, wherein each vessel includes a feeder coupled to a conveying system. The conveying system conveys and blends build material from the vessels. A controller is configured to adjust a composition of the build material by adjusting an amount of material added from each of the vessels by controlling the feeder on each of the vessels.

Abstract: In one example, a pneumatic transport system to transport build material in an additive manufacturing machine includes a conduit, a source of air pressure to pull or push a stream of air through the conduit, a source of build material to introduce a build material into the stream of air, a separator to remove build material from the stream of air, a flow meter downstream from the separator to measure the stream of air flowing through the conduit, and a controller operatively connected to the flow meter and to the source of air pressure and/or the sources of build material to, based on a measurement from the flow meter, adjust a rate of flow of the stream of air in the conduit.

Abstract: Techniques for controlling moisture content of build material in a three-dimensional printer are provided. The system includes a vessel to supply the build material into a build material conveying system. The vessel includes an air inlet to receive a flow of air to fluidize the build material. The system also includes an air conditioner to control the humidity of the air and provide a controlled level of moisture content to the build material.

Abstract: In one example, a pneumatic transport system to transport build material in an additive manufacturing machine includes a conduit, a source of air pressure to pull or push a stream of air through the conduit, a source of build material to introduce a build material into the stream of air, a separator to remove build material from the stream of air, a flow meter downstream from the separator to measure the stream of air flowing through the conduit, and a controller operatively connected to the flow meter and to the source of air pressure and/or the sources of build material to, based on a measurement from the flow meter, adjust a rate of flow of the stream of air in the conduit.

Abstract: According to examples, an apparatus may include a controller to identify a property of particulate material contained in a container and to determine, based upon the identified property of the particulate material, a parameter of a supply of gas fed into a conditioning assembly to condition the particulate material contained in the container. The controller may further control a mechanism to supply the gas at the determined parameter into the conditioning assembly.

Abstract: According to examples, an apparatus may include a hopper having side walls, a bed positioned within the side walls, and a porous membrane supported above the bed. The porous membrane may have a plurality of pores having sizes that are between about 5 microns and about 15 microns and having a density of about 10 and about 30 percent of a material forming the porous membrane. A space between the bed and the porous membrane is to be pressurized with a gas and the gas is to flow through the porous membrane to fluidize particulate material provided on the porous membrane. The apparatus may also include a drain opening extending through the porous membrane and a drain aperture extending through the bed.

Abstract: In one example, a liquid-gas separator includes a composite membrane to pass a gas but not a liquid at a first pressure difference across the membrane and to block the gas passing back through the membrane at a second pressure difference smaller than the first pressure difference.

Abstract: In one example, a vent includes multiple parts each having a different resistivity to passing a gas. The parts are arranged so that the gas may pass through all parts simultaneously as long as the parts remain permeable to the gas.

Abstract: In some examples, a method includes applying a negative pressure to a gas-filled volume through a vent. While a pressure in the volume decreases, the method draws a gas out through the vent and moves a liquid into the volume. The volume is filled with the liquid so that one side of the vent is covered with the liquid and the pressure in the volume increases up to a specified point.

Abstract: A print system or a method to apply a negative pressure to a substantially dry volume through at least one vent.

Abstract: An inkjet material dispenser system includes a printhead member. According to one exemplary embodiment, the printhead member includes at least one drop ejector including an insulating stack layer and a top orifice surface defining an orifice, wherein a ratio of a diameter of the orifice to a height of the insulating stack layer (O/L ratio) is at least 1.0.

Abstract: An inkjet material dispenser system includes a printhead member. According to one exemplary embodiment, the printhead member includes at least one drop ejector including an insulating stack layer and a top orifice surface defining an orifice, wherein a ratio of a diameter of the orifice to a height of the insulating stack layer (O/L ratio) is at least 1.0.

Abstract: An inkjet material dispenser system includes a printhead member. According to one exemplary embodiment, the printhead member includes at least one drop ejector including an insulating stack layer and a top orifice surface defining an orifice, wherein a ratio of a diameter of the orifice to a height of the insulating stack layer (O/L ratio) is at least 1.0.