Extruder height toggling

Abstract

A multi-extruder includes a passive height control mechanism that adjusts the relative height of its extruders without the use of additional, active components. Further, the height control mechanism may employ ramped control surfaces that mitigate noise and vibration by gradually transferring vertical loads while transferring from one active extruder to another.

What is claimed is: 
     
         1 . A three-dimensional printer, comprising:
 a build plate having a substantially planar surface;   a plurality of extruders, each of the plurality of extruders defining a respective extrusion orifice directed toward the build plate, and each extrusion orifice supported above the build plate at a respective height along a z-axis perpendicular to the substantially planar surface;   a cam having a working surface engageable with a first extruder of the plurality of extruders, the working surface of the cam moveable relative to the first extruder to change a z-axis position of the first extruder relative to at least one other one of the plurality of extruders;   a support engageable with the cam to move the cam in a manner that lowers the working surface supporting the first extruder; and   a damper coupled to the support, the damper engageable with the first extruder to receive a z-axis load from the extruder thereby decoupling the first extruder from the cam as the contact with the support lowers the working surface.   
     
     
         2 . The three-dimensional printer of  claim 1 , wherein the plurality of extruders and the cam are movable together in a first direction parallel to the substantially planar surface of the build plate, the support is selectively engageable with the cam to move the cam relative to the plurality of extruders in a second direction, opposite the first direction, and a movement of the cam relative to the first extruder in the second direction decouples the first extruder from the cam. 
     
     
         3 . The three-dimensional printer of  claim 1 , wherein the damper includes an arm cantilevered from the support in a direction parallel to the substantially planar surface of the build plate. 
     
     
         4 . The three-dimensional printer of  claim 3 , wherein the arm includes an inclined surface extending obliquely to the substantially planar surface, the inclined surface positioned to make an initial contact with the first extruder as the damper engages the first extruder, and wherein the z-axis load of the first extruder is received by the arm as the first extruder moves toward the support and away from the build plate along the inclined surface. 
     
     
         5 . The three-dimensional printer of  claim 4 , wherein the inclined surface includes a first surface angled to receive a load from the first extruder as the plurality of extruders move toward the support and a second surface angled to smoothly and continuously lower the first extruder into a working position as the plurality of extruders move away from the support. 
     
     
         6 . The three-dimensional printer of  claim 1 , wherein the first extruder includes a first follower engageable with the working surface of the cam and movable along the working surface of the cam as the working surface moves relative to the first extruder to raise the first follower along the z-axis. 
     
     
         7 . The three-dimensional printer of  claim 6 , wherein the first follower wherein the damper is engageable with the first extruder to decouple the first follower from the working surface of the cam as the support lowers the working surface of the cam adjacent to the first follower. 
     
     
         8 . The three-dimensional printer of  claim 6 , wherein the first extruder includes a second follower movable along the damper, and wherein the z-axis load from the first extruder is receivable by the damper via the second follower. 
     
     
         9 . The three-dimensional printer of  claim 8 , wherein the damper includes a contact surface for the second follower, the contact surface shaped to smoothly lower the first extruder into a working position along the z-axis as the first extruder moves away from the support along an x-axis or y-axis. 
     
     
         10 . The three-dimensional printer of  claim 8 , wherein the first follower is movable along the working surface of the cam in rolling contact with the working surface of the cam, and the second follower is movable along the damper in rolling contact with the support. 
     
     
         11 . The three-dimensional printer of  claim 8 , wherein the first follower and the second follower are spaced apart from one another at least along the z-axis. 
     
     
         12 . The three-dimensional printer of  claim 1 , further comprising a gantry and a carriage, wherein the gantry has a guide surface defining an axis perpendicular to the z-axis, the plurality of extruders are supported on the carriage, and the carriage is movable along the guide surface of the gantry in at least one direction along the axis perpendicular to the z-axis. 
     
     
         13 . The three-dimensional printer of  claim 12 , wherein at least one of the damper or the support is in a fixed location along the axis perpendicular to the z-axis. 
     
     
         14 . The three-dimensional printer of  claim 12 , wherein the working surface of the cam is movable relative to the first extruder along the axis perpendicular to the z-axis. 
     
     
         15 . The three-dimensional printer of  claim 12 , wherein the damper includes an arm cantilevered from the support along the axis perpendicular to the z-axis. 
     
     
         16 . The three-dimensional printer of  claim 15 , wherein the cam is a linear cam, and the working surface of the cam has a first two-dimensional profile in a plane defined by the z-axis and the axis perpendicular to the z-axis. 
     
     
         17 . The three-dimensional printer of  claim 16 , wherein the arm has a second two-dimensional profile in the plane defined by the z-axis and the axis perpendicular to the z-axis, the first extruder includes a second follower, and the arm is engageable with the second follower to move the second follower along the second two-dimensional profile of the arm as the z-axis load of the first extruder is supported on the arm. 
     
     
         18 . The three-dimensional printer of  claim 17 , wherein the first two-dimensional profile of the working surface of the cam is different from the second two-dimensional profile of the arm. 
     
     
         19 . A method comprising:
 moving a plurality of extruders within a plane parallel to a substantially planar surface of a build plate, each of the plurality of extruders defining a respective extrusion orifice supported above the build plate at a respective height above the substantially planar surface;   moving a working surface of a cam relative to a first extruder of the plurality of extruders, movement of the working surface changing a z-axis position of the first extruder relative to the build plate; and   engaging a damper with the first extruder to receive a z-axis load from the first extruder.   
     
     
         20 . The method of  claim 19 , wherein the plurality of extruders and the cam move together in a first direction, the method further comprising engaging a support with the cam to move the cam in a second direction, opposite the first direction, to provide movement of the working surface.