Abstract: Examples relate to methods of printing a 3D printed tamper evident security structure for protecting a feature; the method comprising repeatedly: depositing a layer of build material; doping one or more than one region of the layer of build material using a dopant to influence a respective electrical attribute of one or more than one region associated with a graph of the structure; and agglomerating one or more than one selected portion of the layer of the build material, including the one or more than one doped region of the layer of build material, to form progressively the graph with a predetermined measurable electrical characteristic.

Abstract: Examples relate to methods of printing a 3D printed tamper evident security structure for protecting a feature; the method comprising repeatedly: depositing a layer of build material; doping one or more than one region of the layer of build material using a dopant to influence a respective electrical attribute of one or more than one region associated with a graph of the structure; and agglomerating one or more than one selected portion of the layer of the build material, including the one or more than one doped region of the layer of build material, to form progressively the graph with a predetermined measurable electrical characteristic.

Abstract: Examples of a 3D printing apparatus arranged to perform a print operation using build material, and methods of operating such a 3D printing apparatus, are described. In one case, a 3D printer is arranged to perform a print operation using build material whilst a build material temperature sensed by the printer is below a threshold temperature of the build material. The printer is arranged to obtain a threshold temperature indicator in advance of a respective print operation.

Abstract: An apparatus and method for performing a print operation on a 3D printer (110) are described herein. A 3D printing apparatus comprising a 3D printer (110) is arranged to perform a print operation using build material from a build unit (120) unless a value that identifies a first build material stored in the build unit in a first register, which is set according to an initial build powder fill operation of the build unit (120) by a powder management station, is different from a value in a second register, which is set according to the initial build powder fill operation, or modified in response to, or following, a subsequent opening of the build unit (120).

Abstract: In an example, an apparatus is described that includes a non-resistive heat source, a thermally conductive face, and a temperature detector. The thermally conductive face has a controlled long-wave infrared emissivity and is in thermal contact with the non-resistive heat source. The temperature detector is positioned to detect a temperature of the thermally conductive face.

Abstract: In some examples, a controller is to receive a measurement of an electrical property of an oscillation control system from a sensor, determine, based on the measurement of the electrical property, a frequency of oscillation of a structure vibrated by the oscillation control system in the system, the vibration of the structure to cause passage of a portion of a material through the structure, and estimate a level of a remaining portion of the material at the structure based on the determined frequency of oscillation of the structure.

Abstract: Examples relate to methods of printing a 3D printed tamper evident security structure for protecting a feature; the method comprising repeatedly: depositing a layer of build material; doping one or more than one region of the layer of build material using a dopant to influence a respective electrical attribute of one or more than one region associated with a graph of the structure; and agglomerating one or more than one selected portion of the layer of the build material, including the one or more than one doped region of the layer of build material, to form progressively the graph with a predetermined measurable electrical characteristic.

Abstract: In an example, an apparatus is described that includes a non-resistive heat source, a thermally conductive face, and a temperature detector. The thermally conductive face has a controlled long-wave infrared emissivity and is in thermal contact with the non-resistive heat source. The temperature detector is positioned to detect a temperature of the thermally conductive face.

Abstract: Certain examples described herein relate to build units that are physically connectable to at least one host apparatus of an additive manufacturing system. A build unit comprises at least one controllable device useable in an object building operation. In certain examples, the at least one device is controllable according to first control instructions originating from the at least one host apparatus when the build unit is physically connected to the at least one host apparatus. In certain examples, the at least one device is also controllable according to second control instructions generated independently of the at least one host apparatus when the build unit is not physically connected to the at least one host apparatus.

Abstract: In an example, a print device comprises: a heat pump (102) to extract heat from a fluid source to produce cooled fluid and to transfer the heat from the fluid source to heat a print material (108), wherein the cooled fluid is used to cool a component (106) of the print device.

Abstract: An apparatus and method for performing a print operation on a 3D printer (110) are described herein. A 3D printing apparatus comprising a 3D printer (110) is arranged to perform a print operation using build material from a build unit (120) unless a value that identifies a first build material stored in the build unit in a first register, which is set according to an initial build powder fill operation of the build unit (120) by a powder management station, is different from a value in a second register, which is set according to the initial build powder fill operation, or modified in response to, or following, a subsequent opening of the build unit (120).

Abstract: An apparatus includes a processor to provide a control Signal for a printhead of a printer and a housing including a cavity. The processor is arranged in the cavity. The apparatus has a first opening and a second opening in the housing and in communication with the cavity. The first opening receives a first part of a fluid flow passing the housing, and the second opening discharges heated fluid from the cavity.

Abstract: A safety protection circuit is described, comprising a fuse, a first voltage detection circuit, a first Silicon-Controlled Rectifier, SCR, wherein the first SCR is triggered upon detection of a threshold voltage by the first voltage detection circuit, a second voltage detection circuit, and a second SCR, wherein the second SCR is triggered upon detection of a threshold voltage by the second voltage detection circuit.

Abstract: Examples of a 3D printing apparatus arranged to perform a print operation using build material, and methods of operating such a 3D printing apparatus, are described. In one case, a 3D printer is arranged to perform a print operation using build material whilst a build material temperature sensed by the printer is below a threshold temperature of the build material. The printer is arranged to obtain a threshold temperature indicator in advance of a respective print operation.

Abstract: An example method for measuring the amount of build material in a build material container of a 3D printer may comprise mounting a belt element tensioned between at least two shafts, and attaching a body to the belt element; driving the body towards a surface of the build material while measuring the advance and the speed of the belt element; detecting a reduction of the speed of the belt element, and determining that the body has then contacted the surface of the build material; and determining the position of the surface of the build material based at least on the measured advance of the belt element.

Abstract: Certain examples described herein relate to build units that are physically connectable to at least one host apparatus of an additive manufacturing system. A build unit comprises at least one controllable device useable in an object building operation. In certain examples, the at least one device is controllable according to first control instructions originating from the at least one host apparatus when the build unit is physically connected to the at least one host apparatus. In certain examples, the at least one device is also controllable according to second control instructions generated independently of the at least one host apparatus when the build unit is not physically connected to the at least one host apparatus.

Abstract: There is provided a method and apparatus for controlling harmonics. For each device in an array of devices, a level of harmonic control is acquired to apply to an alternating current voltage powering the device. The level of harmonic control defines a period in a cycle of the alternating current voltage in which to drop the alternating current voltage. For each device in an array of devices, the alternating current voltage powering the device is controlled by dropping the alternating current voltage in the period defined by the acquired level of harmonic control.

Abstract: In an example, a print device comprises: a heat pump (102) to extract heat from a fluid source to produce cooled fluid and to transfer the heat from the fluid source to heat a print material (108), wherein the cooled fluid is used to cool a component (106) of the print device.

Abstract: Methods and apparatus for assessing power usage of at least one printer component in a printer are described. For example, based on a print instruction (the print instruction being to cause the printer to carry out a printing task), power usage requirements of the at least one printer component in carrying out the print instruction may be determined. The power usage may be determined for each of a plurality of time intervals. In some examples, the effect of the printer component(s) in carrying out the print instruction on at least one power quality measure associated with a power supply network which may be connected to the printer may be considered.

Abstract: Example implementations relate to circuits. For example, an implementation includes a detection circuit including a comparator circuit. The comparator circuit includes a first input terminal, a second input terminal, and an output terminal. The detection circuit also includes a reference voltage circuit to provide a set point voltage to the comparator circuit via the first input terminal. The detection circuit further includes a diode to reduce the set point voltage from a first magnitude to a second magnitude when the first magnitude is equal to or lower than a magnitude of the load voltage.