Abstract: In an example, a method includes obtaining object model data describing at least a portion of an object to be generated by additive manufacturing. A color value of a first portion of the object to be generated may be determined, wherein the color value is based on a first color and a second color, different from the first color. Object generation data to generate the object using a fusing agent of the first color and a build material having the second color may be determined by defining a first region of a layer of build material to which fusing agent is to be applied defining a second region of the build material to which detailing agent is to be applied to define an edge of the object and defining a spacing region of build material to separate the first region and second region, wherein the spacing region is defined using parameters selected to provide the color value.

Abstract: Example implementations relate to one or more than one sealing assembly to seal an aperture, coupling two chambers, the aperture being arranged to accommodate a printhead carriage; the assembly comprising: at least a pair of curtains capable of being disposed in a sealing relationship with the aperture; the at least a pair of curtains being capable of being positioned one either side of the printhead carriage, and spooling and unspooling mechanisms comprising a pair of spools onto which the pair of curtains can be spooled and unspooled in response to movement of the printhead carriage to maintain the sealing relationship with the aperture.

Abstract: A 3D printing apparatus to dehumidify and recycle a gas from a 3D printer is disclosed herein. The apparatus comprises: a gas inlet to receive a gas flow from a 3D printer, the gas flow comprising gas with evaporated solvents to be cleaned; a heat exchanger to dehumidify the gas flow from the evaporated solvents, the heat exchanger to cool the gas flow by heat transfer to a cold liquid stream from a chiller to saturate and condensate the solvents from the gas flow; a gas outlet to output the dehumidified gas flow back to the 3D printer; and a controller. The controller is to receive a humidity and temperature measurements from a sensor located downstream from the heat exchanger; compare the humidity and temperature measurements with a target humidity and a target temperature respectively; and control a chiller valve from the chiller based on the comparison to adjust the temperature of the gas flow to set an absolute humidity of the gas flow to a predeterminable value.

Abstract: According to one aspect, there is provided a method of detecting printhead issues in a printer. The method comprises obtaining an image to be printed, generating a first sub-pattern and a second sub-pattern, wherein the first sub-pattern in a pattern to be printed in a first pass comprising a pattern suitable to enable the detection of a printhead issue and wherein the second sub-pattern is the complementary pattern that completes the first sub-pattern such that printing the first and second sub-patterns is equivalent to printing the obtained image, printing the first sub-pattern on a print target, obtaining an image of the printed first sub-pattern, analysing the image of the printed first sub-pattern to determine the presence of a printhead issue and, where appropriate, performing a printhead maintenance operation, and printing the second sub-pattern on the print target.

Abstract: In one example, a material dispensing apparatus comprises a plurality of material containers, wherein the plurality of material containers comprises a first set of material containers arranged to contain a first material and a second set of material containers arranged to contain a second, different, material, and each material container of the second set is located relative to a respective material container of the first set to form a pair of material containers. In use, the material dispensing apparatus is controllable to move across a build platform of an additive manufacturing system.

Abstract: According to one example, there is provided a method of cleaning a filter in a filter housing. The filter has a dirty side at which a dirty airflow is received, and a clean side through which a cleaned airflow flows. The method comprises generating a cleaning airflow at the dirty side of the filter, the cleaning airflow having a predetermined volume and pressure, and generating an extraction airflow to extract from the filter housing the same volume and pressure of air from the filter housing as that generated in the filter housing by the cleaning airflow.

Abstract: A printer is described that comprises a print chamber and an electromagnet moveable within the print chamber. The electromagnet has an on state and an off state. The electromagnet is to collect magnetic powder within the print chamber when in the on state, and to deposit magnetic powder when in the off state.

Abstract: An example method to determine an excess of build material in 3D printing includes providing an amount of build material, spreading the amount of build material to form a layer of build material on a build platform and to leave any excess build material on an excess zone having visible marks thereon and analyzing the marks on the excess zone to determine an excess of build material at the excess zone.

Abstract: An example of a self-cleaning apparatus for a 3D system is disclosed. The apparatus comprises a surface on which build material accumulates during a 3D printing operation. The surface has a profile that slopes generally down towards a collection point. The apparatus also comprises the collection point located in the surface to drain build material from the surface. The apparatus further comprises a vibrating source to cause the surface to vibrate. The apparatus also comprises a controller to control the vibrating source to vibrate, upon determining that a cleaning operation is to be performed, to drive build material accumulated on the surface towards the collection point.

Abstract: In an example, a method includes obtaining object model data describing at least a portion of an object to be generated by additive manufacturing. A color value of a first portion of the object to be generated may be determined, wherein the color value is based on a first color and a second color, different from the first color. Object generation data to generate the object using a fusing agent of the first color and a build material having the second color may be determined by defining a first region of a layer of build material to which fusing agent is to be applied defining a second region of the build material to which detailing agent is to be applied to define an edge of the object and defining a spacing region of build material to separate the first region and second region, wherein the spacing region is defined using parameters selected to provide the color value.

Abstract: Example implementations relate to one or more than one sealing assembly to seal an aperture, coupling two chambers, the aperture being arranged to accommodate a printhead carriage; the assembly comprising: at least a pair of curtains capable of being disposed in a sealing relationship with the aperture; the at least a pair of curtains being capable of being positioned one either side of the printhead carriage, and spooling and unspooling mechanisms comprising a pair of spools onto which the pair of curtains can be spooled and unspooled in response to movement of the printhead carriage to maintain the sealing relationship with the aperture.

Abstract: An example of an additive manufacturing system is disclosed. The example disclosed herein comprises a controller. The controller is to generate a theoretical heatmap representing portions of a layer of build material heated during processing of a previously formed layer supplied to a build bed. The controller is also to calculate, based on the theoretical heatmap, an amount of build material needed in a next layer to be supplied to the build bed. The controller is further to instruct a supply module to supply the amount of build material to the build bed.

Abstract: An example method to determine an excess of build material in 3D printing includes providing an amount of build material, spreading the amount of build material to form a layer of build material on a build platform and to leave any excess build material on an excess zone having visible marks thereon and analyzing the marks on the excess zone to determine an excess of build material at the excess zone.

Abstract: In one example, a material dispensing apparatus comprises a plurality of material containers, wherein the plurality of material containers comprises a first set of material containers arranged to contain a first material and a second set of material containers arranged to contain a second, different, material, and each material container of the second set is located relative to a respective material container of the first set to form a pair of materiel containers. In use, the material dispensing apparatus is controllable to move across a build platform of an additive manufacturing system.

Abstract: In an example, a method comprises controlling material dispensing by a material dispensing apparatus to output a layer of material onto a build platform. The material dispensing apparatus comprises a plurality of pairs of material containers, each pair of material containers movable along a path across the build platform, and comprising a first material container to dispense a first material and a second material container to dispense a second material, to output a band of material along the path, each pair of material containers being arranged with respect to each other pair of material containers to move along respective paths across the build platform to output respective bands of material forming a complete layer of material on the build platform.

Abstract: According to one example, there is provided a method of preparing build material in a build material supply module. The method comprises moving a supply platform within a build material supply module in a predetermined manner to compact build material within the supply module.