A device for depositing a layer of granular material on a deposition surface. The device includes a discharge hopper, a scraper, and a transporter to move the discharge hopper and the scraper relative to the deposition surface. The hopper includes a plurality of discharge holes, aligned in a transverse direction, a top portion and a conical bottom discharge portion. The bottom discharge portion includes two transverse walls that are inclined towards the discharge holes. Each compartment, of a transverse compartmentalization of the discharge portion, includes two walls perpendicular to the transverse walls of the conical bottom discharge portion and inclined towards the discharge holes. Each compartment facing a discharge hole forms a pyramid-shaped conduit in the bottom discharge portion. The consecutive walls of the two compartments being joined at a corner where they meet in the bottom discharge portion.

A device for depositing a layer of granular material on a deposition surface. The device includes a discharge hopper, a scraper, and a transporter to move the discharge hopper and the scraper relative to the deposition surface. The hopper includes a plurality of discharge holes, aligned in a transverse direction, a top portion and a conical bottom discharge portion. The bottom discharge portion includes two transverse walls that are inclined towards the discharge holes. Each compartment, of a transverse compartmentalization of the discharge portion, includes two walls perpendicular to the transverse walls of the conical bottom discharge portion and inclined towards the discharge holes. Each compartment facing a discharge hole forms a pyramid-shaped conduit in the bottom discharge portion. The consecutive walls of the two compartments being joined at a corner where they meet in the bottom discharge portion.

A system for recoating a powder bed includes a build platform holding a powder bed and an electrode assembly including an electrode and an insulating shield. A voltage supply produces a high voltage alternating current and communicates with the powder bed and the electrode. The electrode assembly is positionable over the powder bed, such that when the electrode assembly is over the powder bed, the shield is between the electrode and the powder bed's top surface. The voltage supply produces a high voltage alternating current that creates an alternating electric field between the electrode and the powder bed that causes the powder of the powder bed top surface to oscillate in a region between the shield and the bed and then reposition themselves on the bed such that the top layer of the powder bed is smoother than it was prior to when the powder particles began oscillating.

A system for recoating a powder bed includes a build platform holding a powder bed and an electrode assembly including an electrode and an insulating shield. A voltage supply produces a high voltage alternating current and communicates with the powder bed and the electrode. The electrode assembly is positionable over the powder bed, such that when the electrode assembly is over the powder bed, the shield is between the electrode and the powder bed's top surface. The voltage supply produces a high voltage alternating current that creates an alternating electric field between the electrode and the powder bed that causes the powder of the powder bed top surface to oscillate in a region between the shield and the bed and then reposition themselves on the bed such that the top layer of the powder bed is smoother than it was prior to when the powder particles began oscillating.

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.

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.

A three-dimensional (3D) printing system includes a vessel, a coating subsystem, a calibration block, and a controller. The vessel is configured to contain a photocurable resin having a resin upper surface. The coating subsystem includes a coater module including a coater blade, a lateral movement mechanism coupled to the coater module, a sensor mounted to the coater module, and a vertical actuator system. The calibration block has a calibration surface. The controller is configured to operate the lateral movement mechanism to position the coater blade over the calibration block, operate the vertical actuator system to lower the coater blade into engagement with the calibration surface of the calibration block, operate the sensor to measure a distance to the calibration block, and store the distance as indicative of a vertical position of a lower edge of the coater blade.

A three-dimensional (3D) printing system includes a vessel, a coating subsystem, a calibration block, and a controller. The vessel is configured to contain a photocurable resin having a resin upper surface. The coating subsystem includes a coater module including a coater blade, a lateral movement mechanism coupled to the coater module, a sensor mounted to the coater module, and a vertical actuator system. The calibration block has a calibration surface. The controller is configured to operate the lateral movement mechanism to position the coater blade over the calibration block, operate the vertical actuator system to lower the coater blade into engagement with the calibration surface of the calibration block, operate the sensor to measure a distance to the calibration block, and store the distance as indicative of a vertical position of a lower edge of the coater blade.

A three-dimensional (3D) object printer operates a radiation source to direct radiation emitted by the radiation source through a porous substrate at a first intensity insufficient to cure a material contained in the porous substrate and at a second intensity sufficient to cure the material after the emitted radiation has passed through the porous substrate. The material is applied to the porous substrate by one or more wipers.

A build material dispensing device may include a material spreader to spread an amount of build material along a build platform, and at least one hopper for dispensing the build material. The at least one hopper dispenses a plurality of doses of the build material in front of the progression of the material spreader as the material spreader is moved over the build platform.