Abstract: In one example, a build material recovery system for additive manufacturing includes: a receiving station to receive a portable container containing a build material; a separator to remove build material from a stream of air; a first conduit to carry build material in the stream of air from the receiving station to the separator; a source of negative air pressure to pull the stream of air with the build material through the first conduit from the receiving station to the separator; a humidifier to add moisture to the stream of air; and a second conduit to carry build material from the separator to the receiving station.

Abstract: Example printer finishing apparatus are described herein. An example printer disclosed herein includes an alignment guide, a track to align a sheet relative to the alignment guide, a clamp to move between a raised position and a lowered position relative to the sheet, and a force applicator coupled to the clamp. The force applicator is to cause the sheet to engage the alignment guide when the clamp is in the lowered position.

Abstract: In some examples, a build material recycling system of a three-dimensional (3D) printer can include a build material transport system of the 3D printer, a build material recycling device of the 3D printer that includes a fluidizing membrane and is connected to the build material transport system, and a recycled build material hopper of the 3D printer connected, via the build material transport system, to the build material recycling device.

Abstract: In some examples, a build material recycling system of a three-dimensional (3D) printer can include a build material transport system of the 3D printer, a build material recycling device of the 3D printer that includes a fluidizing membrane and is connected to the build material transport system, and a recycled build material hopper of the 3D printer connected, via the build material transport system, to the build material recycling device.

Abstract: Examples described herein include examples print media handling system including a first media guide assembly comprising a sensor assembly, and a second media guide assembly comprising a retractable pressure plate and disposed opposite the first media guide assembly to guide a print media along a path between the first media guide assembly and second media guide assembly, the pressure plate moveable about an axis perpendicular to the path between an actuated position and a retracted position.

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 one example, a build material recovery system for additive manufacturing includes: a receiving station to receive a portable container containing a build material; a separator to remove build material from a stream of air; a first conduit to carry build material in the stream of air from the receiving station to the separator; a source of negative air pressure to pull the stream of air with the build material through the first conduit from the receiving station to the separator; a humidifier to add moisture to the stream of air; and a second conduit to carry build material from the separator to the receiving station.

Abstract: According to examples, an apparatus may include a first pressure sensor to measure a first pressure level at a first height within a particulate material contained in a container and a second pressure sensor to measure a second pressure level at a second height within the container, in which a gas is to be supplied into the particulate material at a predefined velocity, wherein the first pressure sensor is to measure the first pressure level and the second pressure sensor is to measure the second pressure level while the gas is supplied into the particulate material at the predefined velocity. The apparatus may also include a controller that may determine a pressure gradient from the first pressure level and the second pressure level and calculate a height of the particulate material in the container from the determined pressure gradient.

Abstract: Example printer finishing apparatus are described herein. An example printer disclosed herein includes an alignment guide, a track to align a sheet relative to the alignment guide, a clamp to move between a raised position and a lowered position relative to the sheet, and a force applicator coupled to the clamp. The force applicator is to cause the sheet to engage the alignment guide when the clamp is in the lowered position.

Abstract: An example three-dimensional printer includes a humidity source, a build material reservoir, a conduit between the humidity source and the build material reservoir, an air source to transfer air from the humidity source through the conduit towards the build material reservoir, and a valve assembly connected to the conduit to control a flow of the air in the conduit while the printer enters an inactive mode of operation. The air source is to remain in an active mode of operation. The air source is controlled to transmit the air in the conduit until the air in the conduit adjacent to the build material reservoir reaches a temperature and relative humidity threshold.

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, a valve assembly may include a port structure having a plurality of valve ports that each has an input opening. The valve assembly may also include an isolation plate movably mounted to the port structure, the isolation plate having a plurality of openings and an isolation opening. The isolation plate may be movable between a first position in which the plurality of openings is aligned with the input openings of the plurality of valve ports and a second position in which none of the plurality of openings is aligned with an input opening of the plurality of valve ports.

Abstract: In one example, a system can include a media pathway to transport a media into a stacking region, a clamp pathway to move a clamp along the clamp pathway, and a registration surface. The registration surface may be positioned between an edge of the media pathway and the clamp pathway.

Abstract: In one example, a fusing system for an additive manufacturing machine includes a stationary lighting assembly positioned over a work area and structured to simultaneously irradiate the entire work area with fusing light.

Abstract: Media skew correction is performed by determining a leading edge skew value for the media and selecting a respective media model from a memory for a media type, each media model including a paired slope and an intercept. Based on the paired slope and intercept for the respective media model, differential velocity of a pair of aligned media feed rollers in a media feed mechanism is adjusted to correct a trailing edge skew for the media to within a desired operational window.

Abstract: In one example implementation, a printing device may comprise a number of media skewing rollers to skew a print medium to a predetermined angle with respect to a media feed path and a print engine to print an image on the skewed print medium, the print engine skewing a digital representation of the image based on the predetermined angle such that the image printed is aligned with the print medium. In another example implementation, a printing device may comprise a number of skewing rollers to skew a print medium to a predetermined angle with respect to a media path, a number of pinch rollers to receive the skewed print medium prior to printing, and a print engine skewed to the same predetermined angle as the skewed print medium.

Abstract: A media alignment calibration system determines a slope relating a trailing edge skew value to its paired leading edge skew value and an intercept representing native skew based on a linear regression of a predetermined number of a set of paired leading and trailing edge skew values for a media type stored in a buffer. Based on the slope and intercept, a media model for the media type is updated based on the linear regression to adjust a differential velocity of a pair of aligned media feed rollers in a media feed mechanism to correct both a future native skew and future paired leading and trailing edge skew values in the buffer to within a desired operational window.

Abstract: A skew sensor calibration unit including a scanner providing a scanned image of a sheet as the sheet is conveyed along a transport path, the scanned image including a leading edge of the sheet and a skew detection pattern printed thereon by a printhead. A calibration module measures a top skew of the sheet based on position signals from a plurality of skew sensors indicating a position of a leading edge of a sheet as the sheet is conveyed along the transport path, measure an image skew of the sheet relative to the printhead based on the scanned image, and generates a calibration factor that when applied to the measured top skew provides a calibrated top skew that matches the image skew.

Abstract: In some examples, a build material recycling system of a three-dimensional (3D) printer can include a build material transport system of the 3D printer, a build material recycling device of the 3D printer that includes a fluidizing membrane and is connected to the build material transport system, and a recycled build material hopper of the 3D printer connected, via the build material

Abstract: Media skew correction is performed by determining a leading edge skew value for the media and selecting a respective media model from a memory for a media type, each media model including a paired slope and an intercept. Based on the paired slope and intercept for the respective media model, differential velocity of a pair of aligned media feed rollers in a media feed mechanism is adjusted to correct a trailing edge skew for the media to within a desired operational window.