Abstract: A three-dimensional printing system may include a build platform, the build platform including at least one hole defined through the build platform, a diffuser plate placed below the at least one hole to maintain an amount of build material between a lower surface of the build platform and an upper surface of the diffuser plate, and a flow channel defined around the diffuser plate and sealing the diffuser plate from atmosphere.

Abstract: In one example in accordance with the present disclosure, an additive manufacturing platform is described. The additive manufacturing platform includes a vibrating bed on which a volume of build material is to be disposed. The bed is to vibrate to remove excess build material and operates in at least two extraction modes during a build material extraction period. The additive manufacturing platform also includes a non-vibrating frame to support the vibrating bed.

Abstract: In one example, a platform lift includes a rotationally stationary leadscrew to support a platform, a rotatable nut to drive the leadscrew up and down through a range of motion, a first spring to apply a continuous downward force to the leadscrew throughout the range of motion, and a second spring to apply a continuous upward force to the leadscrew throughout the range of motion.

Abstract: In one example in accordance with the present disclosure, an additive manufacturing build unit is described. The additive manufacturing build unit includes a vibrating bed on which a volume of build material is to be disposed. The bed is to vibrate to remove excess build material. A non-vibrating frame of the build unit supports the vibrating bed. The build unit also includes a bed-frame interface to: couple the vibrating bed to the non-vibrating bed frame, and isolate vibrations to the vibrating bed. A flexible seal of the build unit is disposed between the vibrating bed and non-vibrating frame. The flexible seal prevents build material from contaminating an additive manufacturing system in which the additive manufacturing build unit is disposed and allows relative motion between the vibrating bed and the non-vibrating frame.

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: In one example in accordance with the present disclosure, an additive manufacturing platform is described. The additive manufacturing platform includes a vibrating bed on which a volume of build material is to be disposed. The bed is to vibrate to remove excess build material and operates in at least two extraction modes during a build material extraction period. The additive manufacturing platform also includes a non-vibrating frame to support the vibrating bed.

Abstract: In one example, a platform lift includes a rotationally stationary leadscrew to support a platform, a rotatable nut to drive the leadscrew up and down through a range of motion, a first spring to apply a continuous downward force to the leadscrew throughout the range of motion, and a second spring to apply a continuous upward force to the leadscrew throughout the range of motion.

Abstract: A build unit may include a build chamber, at least two datum apertures defined in at least two opposite sides of the build unit, and at least two alignment posts that seat within the datum apertures to couple the lift system to the build chamber, and to align the lift system in a first coordinate direction relative to the build chamber.

Abstract: A three-dimensional printing system may include a build platform, the build platform including at least one hole defined through the build platform, a diffuser plate placed below the at least one hole to maintain an amount of build material between a lower surface of the build platform and an upper surface of the diffuser plate, and a flow channel defined around the diffuser plate and sealing the diffuser plate from atmosphere.

Abstract: According to one aspect, there is provided a build unit for a 3D printer. The build unit comprises a housing and a build platform movable with the housing, the housing and the platform forming a build chamber. An upper portion of the housing is to, during a print operation, maintain the contents of the upper portion of the build chamber within a first predetermined temperature range, whereas the lower portion of the housing is to allow cooling of the contents of a lower portion of the build chamber.

Abstract: In one example in accordance with the present disclosure, an additive manufacturing build unit is described. The additive manufacturing build unit includes a vibrating bed on which a volume of build material is to be disposed. The bed is to vibrate to remove excess build material. A non-vibrating frame of the build unit supports the vibrating bed. The build unit also includes a bed-frame interface to: couple the vibrating bed to the non-vibrating bed frame, and isolate vibrations to the vibrating bed. A flexible seal of the build unit is disposed between the vibrating bed and non-vibrating frame. The flexible seal prevents build material from contaminating an additive manufacturing system in which the additive manufacturing build unit is disposed and allows relative motion between the vibrating bed and the non-vibrating frame.

Abstract: In one example, an optical position sensing system includes a linear encoder strip, an optical limit switch having an actuator on the encoder strip to activate the limit switch, and an optical reader to read the encoder strip.