WO2023086861A1

WO2023086861A1 - Topographic compensation for a three-dimensional dual nozzle printer head printer

Info

Publication number: WO2023086861A1
Application number: PCT/US2022/079600
Authority: WO
Inventors: Alexis EHRLICH; Scott Matthews; Matthew SKOLAUT; Yasushi Mizuno
Original assignee: Essentium Ipco, Llc
Priority date: 2021-11-12
Filing date: 2022-11-10
Publication date: 2023-05-19

Abstract

A three-dimensional printer head, three-dimensional printer, and a method of compensating for build surface topography in a three-dimensional printer. The three-dimensional printer head including a feed plate, a first feed assembly and second feed assembly moveably affixed to the feed plate. The feed assemblies each including a feed nozzle. At least one of a sensor and a sensor trigger mounted to each of the first feed assembly and second feed assembly and the other of the first sensor and first sensor trigger mounted to the feed plate of each of the first feed assembly and the second feed assembly. The three-dimensional printer includes the printer head, a support bed, and a controller including executable code to compensate for build surface topography.

Description

TOPOGRAPHIC COMPENSATION FOR A THREE-DIMENSIONAL DUAL

NOZZLE PRINTER HEAD PRINTER

FIELD

[0001] The present disclosure is directed to topographic compensation for a three- dimensional printer with a dual nozzle printer head.

BACKGROUND

[0002] In extrusion based additive manufacturing processes, the build plate and support bed upon which the filament is extruded upon is a relatively significant factor in successfully printing a three-dimensional part as the first layer builds off the build surface and the next layers build off the previously deposited layer. An unlevel surface and lack of flatness, due to surface roughness, waviness, or warping, imparts aberrations in the printed component, some which become amplified as the number of printed layers increase. Often leveling of the support bed can be mechanically adjusted, but in many instances, flatness is an immutable characteristic of a build surface unless a different build surface is supplied, or the build surface is altered. Build surfaces are formed from various materials, such as glass, polymers, metals and metal alloys, or composites, and by a number of manufacturing processes. Glass surfaces, such as float glass, may be relatively flat, whereas polymer sheets are compliant but are relatively less flat than glass. Some support beds may exhibit a deviation of up to a few millimeters across the surface of the bed. Further, the use of certain build surfaces is sometimes dictated by the material that is being extruded in the additive manufacturing process. [0003] While it is possible to change out a build surface for another build surface having a higher degree of surface flatness, this may not always be possible. Another method used to compensate for reduced flatness of the build surface includes using a sensor in the printer head to measure the distance, in the z-axis, between the printer head and the build surface at various points across the build surface and then adjusting the distance between the printer head and the build surface during printing by raising or lowering the build surface or printer head. Such measurements may be complicated by the addition of a second nozzle in the printer head.

[0004] Thus, while current compensation systems and methods achieve their intended purpose, there remains room for the development of new and improved systems and methods for compensating for support bed surface aberrations.

SUMMARY

[0005] According to various aspects, the present disclosure is directed to a three- dimensional printer head. The three-dimensional printer head includes a feed plate, a first feed assembly moveably affixed to the feed plate, wherein the first feed assembly includes a first extrusion nozzle, and a second feed assembly moveably affixed to the feed plate, wherein the second feed assembly includes a second extrusion nozzle. The three-dimensional printer head also includes a cam rotatably mounted to the feed plate, configured to move the first feed assembly and second feed assembly relative to each other. The three-dimensional printer head further includes at least one of a first sensor and a first sensor trigger mounted to the first feed assembly and the other of the first sensor and first sensor trigger mounted to the feed plate and at least one of a second sensor and a second sensor trigger mounted to the second feed assembly and the other of the second sensor and the second sensor trigger mounted to the feed plate. [0006] In embodiments, the three-dimensional printer head further includes a first slide affixed to the feed plate, a second slide affixed to the feed plate, a first mating channel affixed to the first feed assembly receiving the first slide, and a second mating channel affixed to the second feed assembly receiving the second slide.

[0007] In any of the above embodiments, the first sensor is mounted to the feed plate and the sensor trigger is mounted to the first feed assembly. In further embodiments, the first sensor includes two prongs and the first sensor trigger is movable between the two prongs.

[0008] In any of the above embodiments, the second sensor is mounted to the feed plate, and a second sensor trigger mounted to the second feed assembly. In further embodiments, the second sensor includes two prongs and the first sensor trigger is movable between the two prongs.

[0009] In further embodiments of the above, the first sensor and second sensor are optical sensors.

[0010] In any of the above embodiments, the cam includes a first segment and a second segment, and the three-dimensional printer head further includes a first yoke extending from the first feed assembly and rides on the first segment of the cam, and a second yoke extending from the second feed assembly and rides on the second segment of the cam. In further embodiments, the three-dimensional printer head further includes a first hard stop for the first yoke affixed to the second feed assembly and a second hard stop for the second yoke affixed to the first feed assembly.

[0011] In any of the above embodiments, the three-dimensional printer head is supported on a x, y-axis gantry in a three-dimensional printer, wherein the printer head is movable in an x-y plane. In further embodiments, the three-dimensional printer includes a support bed having a support surface, wherein the support bed is movable relative to the printer head along a z-axis, and a build plate is removably positioned on the support surface. [0012] According to various additional aspects, the present disclosure relates to a method off compensating for build surface topography. The method includes measuring a first position of the build surface in the z-axis at a first number of points on the build surface when the build surface is pressed against a first extrusion nozzle affixed to a printer head. The method further includes creating a first topographic compensation map based on the position of the build surface in the z- axis measured at the first number of points on the build surface. The method also includes storing the first topographic compensation map in non-transient memory included in the three-dimensional printer for reference during printing with the first extrusion nozzle. The three-dimensional printer head includes any of the above-described embodiments of the three-dimensional printer head.

[0013] In embodiments, the method further includes printing with the first extrusion nozzle and adjusting a printing distance between the first extrusion nozzle and the build surface while printing based on the first topographic compensation map.

[0014] In any of the above embodiments, the method further includes measuring a second position of the build surface in the z-axis at a second number of points on the build surface when the build surface is pressed against the second extrusion nozzle. In further embodiments, the method includes creating a second topographic compensation map based on the second position of the build surface measured at the second number of points on the build surface. In alternative embodiments, the method includes augmenting the first topographic map based on the second position of the build surface measured at the second number of points on the build surface. In yet further embodiments, the method includes printing with the second extrusion nozzle, and adjusting a printing distance between the second extrusion nozzle and the build surface while printing based on the second topographic compensation map. [0015] According to various additional aspects, the present disclosure relates to a three- dimensional printer. The three-dimensional printer includes any of the above-described embodiments of the three-dimensional printer head, which is moveable in an x-y plane. The three- dimensional printer also includes a support bed having a support surface, wherein the support bed is movable relative to the printer head along a z-axis. The support bed also includes a build plate removably positioned on the support surface. The three-dimensional printer further includes a controller. The controller includes executable code to measure a first position of the build surface in the z-axis at a first number of points on the build surface when the build surface is pressed against a first nozzle affixed to a printer head. The controller also includes executable code to create a first topographic compensation map based on the position of the build surface in the z- axis measured at the first number of points on the build surface and store the first topographic compensation map in non-transient memory included in the three-dimensional printer for reference during printing with the first extrusion nozzle.

[0016] In embodiments of the above, the controller further includes executable code to print with the first extrusion nozzle, and adjust a printing distance between the first extrusion nozzle and the build surface while printing based on the first topographic compensation map.

[0017] In additional embodiments of the above, the controller further includes executable code to measure a second position of the build surface in the z-axis at a second number of points on the build surface when the build surface is pressed against the second extrusion nozzle, one of a) create a second topographic compensation map, or b) augment the first topographic compensation map using the measured second position at the second number of points; and adjusting a printing distance between the second extrusion nozzle and the build surface while printing with the second extrusion nozzle. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above-mentioned and other features of this disclosure, and the manner of attaining them, will become more apparent and better understood by reference to the following description of embodiments described herein taken in conjunction with the accompanying drawings, wherein:

[0019] FIG. 1 illustrates a schematic of a three-dimensional printer, according to an embodiment of the present disclosure;

[0020] FIG. 2 illustrates a cross-section of a support bed including a build surface, according to an embodiment of the present disclosure;

[0021] FIG. 3 illustrates a printer head and x-y gantry carried in the upper portion of a printer frame, according to an embodiment of the present disclosure;

[0022] FIG. 4 illustrates a printer head including two extrusion nozzles, according to an embodiment of the present disclosure;

[0023] FIG. 5 illustrates an exploded view of the printer head of FIG. 4, according to an embodiment of the present disclosure;

[0024] FIG. 6 illustrates a side, rear perspective view of the printer head of FIG. 4, according to an embodiment of the present disclosure;

[0025] FIG. 7 illustrates rear view of one of the feed assemblies, according to an embodiment of the present disclosure;

[0026] FIG. 8a illustrates an example of the positioning of the sensor trigger relative to the prongs of the sensor when a first nozzle is in the z-prime mode for measuring topographic aberrations in the build surface, according to an embodiment of the present disclosure; [0027] FIG. 8b illustrates an example of the positioning of the sensor trigger relative to the prongs of the sensor when a first nozzle is in the z-prime mode for measuring topographic aberrations in the build surface and is pressed into the build surface, according to an embodiment of the present disclosure;

[0028] FIG. 9a illustrates an example of the positioning of the sensor trigger relative to the prongs of a sensor when a second nozzle is in the z-prime mode for measuring topographic aberrations in the build surface, according to an embodiment of the present disclosure;

[0029] FIG. 9b illustrates an example of the positioning of the sensor trigger relative to the prongs of a sensor when a second nozzle is in the z-prime mode for measuring topographic aberration in the build surface and is pressed into the build surface, according to an embodiment of the present disclosure;

[0030] FIG. 10a illustrates an example of the positioning of the cam and yokes when the first nozzle is in print mode, according to an embodiment of the present disclosure;

[0031] FIG. 10b illustrates an example of the positioning of the cam and yokes when a second nozzle is in print mode, according to an embodiment of the present disclosure;

[0032] FIG. I la illustrates an example of the positioning of the cam and yokes when the first nozzle is in z-prime mode for measuring build surface topography, according to an embodiment of the present disclosure;

[0033] FIG. 1 lb illustrates an example of the positioning of the cam and yokes when the second nozzle is in z-prime mode for measuring build surface topography, according to an embodiment of the present disclosure;

[0034] FIG. 12 illustrates schematic of a controller for a three-dimensional printer, according to an embodiment of the present disclosure; [0035] FIG. 13 illustrates an embodiment flow chart for performing a method of adjusting for topographic aberrations in the build surface, according to an embodiment of the present disclosure; and

[0036] FIG. 14 illustrates an embodiment of the arrangement of points for measuring Dz on a build surface, according to an embodiment of the present disclosure.

[0037] The drawings described herein are for illustration purposes and are not intended to limit the scope of the present disclosure in anyway.

DETAILED DESCRIPTION

[0038] The present disclosure is directed to topographic compensation for a three- dimensional printer with a dual nozzle printer head, including a three-dimensional printer and method for compensating for topographic aberrations in the build surface.

[0039] An aspect of a three-dimensional printer is illustrated in FIG. 1. The three- dimensional printer 100 generally includes an enclosure 102 defining a process chamber 104 and a support bed 106 including a build surface 111 is supported within the process chamber 104. In the illustrated aspect, the support bed 106 includes a support surface 108 onto which a build plate 110 is placed, wherein the build plate 110 includes a build surface 111. The three-dimensional printer 100 further includes a printer head 112 that deposits filament 114 onto the build plate 110 to form the three-dimensionally printed object 116. The printer head 112 is supported relative to the build plate 110 on an x, y-axis gantry 118, which provides motion along x, y-axes 16, 18 in the x-y plane. The support bed 106 is moved in the z-axis 20 relative to the printer head 112 by a z- axis gantry 120, moving along z-axis 20. In further aspects, the printer head 112 may be moved in the z-axis 20 and the support bed 106 may be moved in the x, y-axes 16,18. Filament 114 is stored in one or more canisters 122 and provided to the printer head 112 by a filament drive system 124. While only one filament 114 and one filament drive system 124 are illustrated in FIG. 1, it should be appreciated that two filaments 114, 214 and two filament drive systems 124, 224 may be present. A controller 128 is provided to control the various functions of the three-dimensional printer 100.

[0040] The support bed 106 is generally rectangular in shape, as illustrated in FIG. 1, but may assume alternate geometries, such as circular, oval, or square. In the aspect illustrated in FIG. 2, the support bed 106 including a build surface 111. The support bed 106 is formed from one or more layers 130, 132, 134. In the aspect illustrated, a heated layer 132, including one or more heating elements, is sandwiched between a composite layer 130 and a plate 134. The composite layer 130 includes, for example, a fiberglass-epoxy laminate composite or carbon fiber-epoxy laminate. The plate 134 provides a support surface 108. The plate 134 includes, for example, stainless steel, aluminum, or an aluminum alloy. Further, in aspects, the support surface 108 of the plate 134 exhibits a flatness in the range of 0.00 mm to 3.00 mm, including all values and ranges therein, over the entire length and width of the plate, including all values and ranges therein, regardless of any other features such as the openings 136 defined in the support surface 108. In this aspect, a build plate 110 is placed on the support surface 108 and is retained against the support surface 108 by magnets 135 secured in the openings 136. However, the openings 136, in alternative embodiments, may provide vacuum ports for retaining the build plate 110 by way of vacuum pressure. The build plate 110 provides a build surface 111; however, it should be appreciated that in alternative aspects, the support surface 108 provides the build surface 111. In aspects, the build plate 110 is formed from materials such as polycarbonate, polypropylene, glass, spring steel, stainless steel, aluminum alloys. The build surface I l l is not completely flat and exhibits a number of aberrations 137, such as waviness, warping, or surface roughness. These aberrations cause a deviation d from an x, y-plane 138 generally defined by the build surface 111. As illustrated, the x, y-plane 138 is defined by the minimization of distance between the measured points and the plane. However, the x, y-plane 138 defined by the build surface 111 may alternatively be defined by utilizing other mathematical functions.

[0041] The support bed 106 is supported within the three-dimensional printer using a z- axis gantry 120, integrated in the lower frame 142 of the three-dimensional printer 100, an aspect of which is illustrated in FIG. 3. The z-axis gantry 120 includes a gantry table 141 for supporting the support bed 106. The gantry table 141 is connected to at least one z-axis linear adjustment drive 144. While in the illustrated aspect includes a ball screw assembly, in alternative aspects, other linear drives may be used, such as a roller screw or an acme screw assembly. The z-axis linear adjustment drive 144 raises and lowers the support bed 106 relative to the printer head 112, up and down in the direction of z-axis 20.

[0042] The printer head 112 is carried by the upper frame 160 of the three-dimensional printer 100, which is secured to the lower frame 142. The printer head 112 is supported by a gantry 118. The gantry 118 is configured to move along parallel support rails 164 (a second support rail, not visible, is provided opposite from the first support rail 164 in the upper frame 160) in the x- axis 16, driven by a linear motor or other drive mechanism. Further, the printer head 112 is configured to move back and forth along the y-axis 18 in a support frame 166 provided by the gantry 118, again propelled by a linear motor or other drive mechanism. The x-axis 16 being coplanar and perpendicular to the y-axis 18 and providing movement in an x-y, plane for the printer head 112. [0043] An aspect of a printer head 112 is illustrated in FIG. 4. The printer head 112 includes two extrusion nozzles 170, 270, which are typically heated. The printer head 112 further includes a feed assembly 172, 272 for each extrusion nozzle 170, 270. The feed assemblies 172, 272 each include one or more feed hob pairs 174, 274, 175, 275 that guide and feed the filament 114, 214 into the extrusion nozzles 170, 270. The printer head 112 further includes a cam 316 for moving the first feed assembly 172 and the second feed assembly 272 relative to each other. As one feed assembly, 172, 272, is moved up from the build surface 111 in the z-axis 20, the other feed assembly, 172, 272, is moved down towards the build surface 111.

[0044] With reference to FIGS. 5 through 9a and 9b, the extrusion nozzles 170, 270 and feed assemblies 172, 272 travel in the z-axis 20 on slides 190, 192, 290, 292 connected to the feed plate 198. Feed assemblies 172, 272 each include one or more mating channels 194, 196, 294, 296 to receive the slides (note 194, 196 are not illustrated in FIG. 7). In aspects, the mating channels 194, 196, 294, 296 include bearings. The slides 190, 192, 290, 292 are mounted to a feed plate 198, which is mounted to the extruder motor 300. A sensor 178, 278 corresponding to each nozzle 170, 270 and each feed assembly 172, 272 is mounted to the feed plate 198. In aspects, the sensors 178, 278 are optical sensors, each including an emitter and a receiver. In the illustrated aspect, the sensors 178, 278 are an optical sensor including two prongs 302, 304, 402, 404, wherein each prong 302, 304, 402, 404 includes one of an emitter and a receiver, or one prong 302, 402 includes an emitter and receiver and the other prong 304, 404 may include a reflector. In the illustrated aspect, the sensors 178, 278 are mounted to the rear 306 of the feed plate 198 and extend through openings 308, 408 in the feed plate 198. A sensor trigger 310, 410 is affixed to each feed assembly 172, 272 and extends from the rear 312, 412 of each feed assembly 172, 272. It should be appreciated that the arrangement may be reversed, wherein the sensor triggers 310, 410 are connected to the feed plate 198 and the sensors 178, 278 are each connected to a feed assembly 172, 272. The height of the sensor trigger 310, 410 may be adjusted up and down relative to the feed assembly 172, 272.

[0045] In aspects, the printer head 112 is arrange-able in two modes for each nozzle 170, 270. The first mode is a print mode, wherein one of the nozzles 170, 270 is positioned above the build surface 111 to deposit filament traces onto the build surface 111. The second mode is a z- prime mode, which is used to make the measurements needed for topographic compensation.

[0046] Beginning with z-prime mode, FIGS. 8a, 8b illustrate the feed assemblies 172, 272 and nozzles 170, 270 arranged in z-prime mode for the first nozzle 170. FIGS. 9a and 9b illustrate the feed assemblies 172, 272 and nozzles 170, 270 arranged in z-prime mode for the second nozzle 270. When one of the nozzle tips 171, 271 touches the build surface 111, the sensor trigger 310, 410 is displaced relative to the sensor 178, 278, triggering the sensor 178, 278. The position of the build surface 111 is in the z-axis 20 is recorded and a delta, Dz, from the “ideal” expected position in the z-axis 20 is stored. The measurement is repeated across the build surface 111 at various points to create a topographic map of the build surface 111.

[0047] In the illustrated aspect, if the sensor triggers 310, 410 are located between the prongs 302, 304, 402, 404, then the sensors 310, 410 are untriggered and when the sensor triggers 310, 410 move out from between the prongs 302, 402, 304, 404 the sensors 178, 278 are triggered. It should be appreciated that the opposite arrangement may be used, wherein when the sensor trigger 310, 410 is located between the prongs 302, 402, 304, 404 the sensor 178, 278 is triggered, and when the sensor trigger 310, 410 is located adjacent to, but not between the prong 302, 402, 304, 404, the sensor 178, 278 is untriggered. While an optical sensor is described herein, it may be appreciated that the sensors 178, 278 is at least one of a contact sensor, such as a mechanical push button sensor, or a non-contact sensor, such as a capacitive displacement sensor, an inductive sensor, a magneto-inductive sensor, a laser sensor, and an optical sensor.

[0048] As alluded to above, when the support bed 106 is raised, the build surface 111 touches the extrusion nozzle 170, 270 which causes the extrusion nozzle 170 to rise in the z-axis 20 and displace the sensor trigger 310, 410 relative to the sensor 178, 278. When the sensor trigger 310, 410 is displaced and the sensor is 178, 278 triggered, the position of the build surface I l l is measured relative to a given point in the z-axis 20 to provide the distance Dz between the nozzle 170, 270 and the build surface 111 at that x, y-location on the build surface 111.

[0049] To move each nozzle 170, 270 relative to the build surface I l l a rotatable cam 316 mounted, either directly or indirectly, to the feed plate 198 is used. With reference now made to FIGS. 5, 10a, 10b, I la and 1 lb, it is noted that each feed assembly 172, 272 includes a yoke 320, 420 extending from the feed assemblies 172, 272 toward the center of the printer head 112 in the x-axis 16. The yokes 320,420 are arranged such that one yoke 420 is closer to the feed plate 198 than the other yoke 320. Further, each yoke 320, 420 at least partially surrounds and rides on a segment 322, 422 of the cam 316. The segment 422 of the cam 316 proximal to the feed plate 198 receives the yoke 420 also positioned proximal to the feed plate 198 and the segment 322 of the cam 316 distal from the feed plate 198 receives the yoke 320 positioned distal to the feed plate 198.

[0050] In aspects, the segments 322, 422 of the cam 316 are congruent, positioned off- center from the rotational axis R of the cam 316, and are 180 degrees out of phase from each other. As the cam 316 is rotated, the segments 322, 422 drive up and down the yokes 320, 420 and the feed assemblies 172, 272 to which the yokes 320, 420 are connected. When one nozzle 170 is proximal to the build surface 111 for the purposes of printing or mapping, the other nozzle 270 is up and vice versa. The cam 316 is then rotated when it is desired to switch nozzles 170, 270. It should be appreciated that the feed assemblies 172, also move up and down on the slides 190, 290, 192, 292 as they are being moved by the yokes 320, 420 and cam 316.

[0051] A hard stop 326, 426 is provided for each yoke 320, 420 on the opposing feed assembly 172, 272, such that the hard stop for the first yoke 320 is provided on the second feed assembly 272 and the hard stop for the second yoke 420 is provided on the first feed assembly 172. The hard stops 326, 426 prevent the nozzles 170, 270 from traveling too far towards the build surface 111 in the z-direction and to prevent the build surface 111 being raised too far up against the nozzle 170, 270. In addition, the yokes 320, 420, and specifically the prongs of the yoke 320, 420 exhibit relatively little deflection, less than 10 micrometers, and in aspects 8 micrometers or less. This limited degree of deflection is understood to improve the accuracy of the measurements made in the z-direction and prevent erroneous triggering of the sensors 178, 278.

[0052] As noted above, each nozzle 170, 270 is positionable between a first, print mode, and a second, z-prime mode. When a nozzle 170, 270 is positioned in the print mode, the segment 322, 422 of the cam 316 associated with the yoke 320, 420 and feed assembly 172, 272 to which the printing nozzle 170, 270 (the nozzle 170, 270 designated to print at a given time) is attached to is rotated to its lowest point in the z-direction. This point is understood as zero degrees. The cam 316 may then be rotated by 30 degrees to lift the nozzle 170, 270 up sufficiently for the purposes of performing measurements across the build surface 111 to determine the aberrations in the build surface 111. This mode is z-prime mode.

[0053] In aspects, the cam motor 330 is affixed to the extruder motor 300. The cam motor 330 includes a keyed drive spindle 332 that extends through the feed plate 198 and is connected to the cam 316 in a non-rotatable manner, such that when the drive spindle 332 is rotated, the cam 316 rotates. The number of degrees of rotation of the cam 316 is determined by the number of counts per rotation of the cam motor 330. Alternatively or additionally, an encoder may be used to determine the degrees of rotation.

[0054] FIG. 10a illustrates the first nozzle 170 in print mode and FIG. 10b illustrates the second nozzle 270 in print mode. When the first nozzle 170 is print mode, the cam 316 is rotated such that the cam segment 322 interacting with the first yoke 320 of the first feed assembly 272 is positioned at the 0 degree position. With the cam 316 in this position, the first nozzle 170 and feed assembly 172 are moved closer to the build surface 111 in the z-axis direction 20 and the second nozzle 270 and the second feed assembly 272 are moved away from the build surface 111 in the z-axis direction 20. When the second nozzle 270 is in print mode, the cam 316 is rotated such that the cam segment 422 interacting with the second yoke 420 of the second feed assembly 272 is positioned at the 0 degree position.

[0055] FIG. I la illustrates the first nozzle 170 in z-prime mode and FIG. 11b illustrates the second nozzle 270 in z-prime mode. When the first nozzle 170 is in z-prime mode the first cam segment 322 is rotated 30 degrees counterclockwise, i.e., towards the first feed assembly 172, from the 0 degree position, lifting the first feed assembly 172 up slightly, such as in the range of 2 millimeters to 6 millimeters including all values and increments therein, from the build surface 111 in the z-axis 20 direction. When the second nozzle 270 is in z-prime mode the second cam segment 422 is rotated clockwise 30 degrees from the 0 degree position towards the second feed assembly 272, lifting the second feed assembly 272 up slightly, such as in the range of 2 millimeters to 6 millimeters including all values and increments therein, from the build surface 111 in the z-axis 20 direction. While reference is made to rotating the cam 316 30 degrees from the zero degree position to position each nozzle 170, 270 in z-prime mode, the rotation of the cam 316 between the print mode and the z-prime mode may vary between, e.g., 10 degrees to 60 degrees, including all values and ranges therein.

[0056] FIG. 12 illustrates a schematic of the three-dimensional printer 100 including the controller 128, which is connected to the printer head 112, including the sensors 178, 278 and the extrusion nozzles 170, 270; the support bed 106, if heated or otherwise functionalized; and the z- axis linear adjustment drive 144. The connections are electrical connections facilitated by conductive wires 180 or wireless connections facilitated by radio frequency or optical communication protocols. The controller 128 includes one or more processors 182, such as microprocessors, which execute executable code to control the various functions of the three- dimensional printer 100, including the methods further described herein. The executable code is stored in a non-transient memory device 184 accessible to the controller 128, such as randomaccess memory, read only memory, non-volatile memory, such as flash memory, erasable programmable read only memory, electrically erasable programmable read only memory, digital versatile discs, and compact discs. In aspects, the executable code includes initialization protocols as well as g-code and m-code used in printing a three-dimensional object 116 (see FIG. 1). In aspects, the m-code is used to select and run the printer head 112, whereas the g-code includes the movements used to print the three-dimensional object 116.

[0057] With reference again to FIGS. 1 through 14, when the support bed 106, or build plate 110, providing the build surface 111, is placed into the three-dimensional printer 100, the build surface 111 deviates from being completely flat and exhibits topographic aberrations. To compensate for the topographic aberrations of the build surface 111, and with reference to FIG. 13, a method 1000 of compensating for the topographic aberrations in the build surface 111 begins at block 1002 by measuring a position of the build surface 111 in the z-axis 20, when the build surface touches the extrusion nozzle 170, 270 in z-prime mode and triggers the sensor 178, 278 associated with the nozzle 170, 270. The build surface 111 is moved up relative to the extrusion nozzle 170, from a starting point in the z-axis 20, and a position of the build surface 111 in the z- axis 20 is taken when the build surface 111 presses against the extrusion nozzle 170, 270 in z- prime mode, as described above, and triggers the sensor 178, 278. The difference, or delta Dz, between the position of the build surface 111 and the expected or ideal build surface 111 location of the build surface 111 when it is raised towards the nozzle 170, 270 is determined. It should be appreciated that in other configurations, where the printer head 112 may move in the z-axis 20, the printer head 112 may be moved relative to the build surface 111, or both the printer head 112 and the build surface 111 may move relative to each other.

[0058] At block 1004, a topographic compensation map of the build surface 111 is then created. While the points 109 for measuring position Dz are illustrated as being in a particular pattern in FIG. 14, it should be appreciated that other patterns or random points 109 for measuring position Dz may be taken. It should also be appreciated that the more points 109 that are measured, the longer the process of preparing a topographic compensation map will take and, therefore, in some aspects, interpolation of the measurements of position Dz between the various points 109 of measurement of the extrusion nozzle 170 and the build surface 111 may be performed to predict the position Dz between the extrusion nozzle 170 and the build surface 111 between the points 109 measurements of position Dz. The process of taking measurements is then optionally repeated for the second nozzle 270 at block 1006 and a second topographic compensation map is created at block 1008 or the first topographic compensation map is augmented. Again, as may be appreciated, the topographic compensation map may differ between the print nozzles 170, 270 due to slight variations in the nozzles 170, 270, the feed assemblies 172, 272 or the yokes 322, 422. The user or the controller 128 selects the print nozzle 170, 270 that will perform a printing operation at block 1010 and the controller 128, based on the print nozzle 170, 270 selection, inserts the appropriate topographic compensation map to use during printing. The topographic compensation map, in aspects, is stored in non-transient memory, and includes the measurements of position Dz taken at points 109 across the build surface 111. At block 1010, during printing, the printing distance between the build surface 111 and extrusion nozzle 170 or other fixed point on the printer head 112, is adjusted, based on the measurements of position Dz at points 109 across the build surface 111, to maintain a relatively consistent distance between the build surface 111 and extrusion nozzle 170 during printing. [0059] The system and methods of the present disclosure offers several advantages. These advantages include a sensor system for use with two extrusion nozzles on a single printer head. These advantages further include the ability to select a topographic map appropriate for a given printer nozzle.

[0060] The description of the present disclosure is merely exemplary in nature and variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure.

Claims

CLAIMS What is claimed is:

1. A three-dimensional printer head, comprising: a feed plate; a first feed assembly moveably affixed to the feed plate, wherein the first feed assembly includes a first extrusion nozzle; a second feed assembly moveably affixed to the feed plate, wherein the second feed assembly includes a second extrusion nozzle; a cam rotatably mounted to the feed plate, configured to move the first feed assembly and second feed assembly relative to each other; at least one of a first sensor and a first sensor trigger mounted to the first feed assembly and the other of the first sensor and first sensor trigger mounted to the feed plate; and at least one of a second sensor and a second sensor trigger mounted to the second feed assembly and the other of the second sensor and the second sensor trigger mounted to the feed plate.

2. The three-dimensional printer head of claim 1, further comprising: a first slide affixed to the feed plate; a second slide affixed to the feed plate; a first mating channel affixed to the first feed assembly receiving the first slide; and a second mating channel affixed to the second feed assembly receiving the second slide.

3. The three-dimensional printer head of claim 1, wherein the first sensor is mounted to the feed plate; and the sensor trigger is mounted to the first feed assembly.

4. The three-dimensional printer head of claim 3, wherein the first sensor includes two prongs and the first sensor trigger is movable between the two prongs.

5. The three-dimensional printer head of claim 3, therein the second sensor mounted to the feed plate; and the second sensor trigger mounted to the second feed assembly.

6. The three-dimensional printer head of claim 5, wherein the second sensor includes two prongs and the first sensor trigger is movable between the two prongs.

7. The three-dimensional printer head of claim 5, wherein the first sensor and second sensor are optical sensors.

8. The three-dimensional printer head of claim 1, wherein the cam includes a first segment and a second segment, and the three-dimensional printer head further comprises: a first yoke extending from the first feed assembly and rides on the first segment of the cam; and a second yoke extending from the second feed assembly and rides on the second segment of the cam.

9. The three-dimensional printer head of claim 8, further comprising: a first hard stop for the first yoke affixed to the second feed assembly; and a second hard stop for the second yoke affixed to the first feed assembly.

10. The three-dimensional printer head of claim 9, wherein the three-dimensional printer head is supported on a x, y-axis gantry in a three-dimensional printer, wherein the printer head is movable in an x-y plane.

11. The three-dimensional printer head of claim 10, wherein the three-dimensional printer includes a support bed includes a support surface, wherein the support bed is movable relative to the printer head along a z-axis, and a build plate is removably positioned on the support surface.

A method of compensating for build surface topography in a three-dimensional printer, comprising: measuring a first position of the build surface in a z-axis at a first number of points on the build surface when the build surface is pressed against a first extrusion nozzle affixed to a three-dimensional printer head; creating a first topographic compensation map based on the position of the build surface in the z-axis measured at the first number of points on the build surface; and storing the first topographic compensation map in non-transient memory included in the three-dimensional printer for reference during printing with the first extrusion nozzle, wherein the three-dimensional printer head includes: a feed plate; a first feed assembly moveably affixed to the feed plate, wherein the first feed assembly includes the first extrusion nozzle; a second feed assembly moveably affixed to the feed plate, wherein the second feed assembly includes a second extrusion nozzle; a cam rotatably mounted to the feed plate, configured to move the first feed assembly and second feed assembly relative to each other; at least one of a first sensor and a first sensor trigger mounted to the first feed assembly and the other of the first sensor and first sensor trigger mounted to the feed plate; and at least one of a second sensor and a second sensor trigger mounted to the second feed assembly and the other of the second sensor and the second sensor trigger mounted to the feed plate.

13. The method of claim 12, further comprising: printing with the first extrusion nozzle; and adjusting a printing distance between the first extrusion nozzle and the build surface while printing based on the first topographic compensation map.

14. The method of claim 12, further comprising: measuring a second position of the build surface in the z-axis at a second number of points on the build surface when the build surface is pressed against the second extrusion nozzle.

15. The method of claim 14, further comprising: creating a second topographic compensation map based on the second position of the build surface measured at the second number of points on the build surface.

16. The method of claim 14, further comprising: augmenting the first topographic map based on the second position of the build surface measured at the second number of points on the build surface.

17. The method of claim 15, further comprising: printing with the second extrusion nozzle; and adjusting a printing distance between the second extrusion nozzle and the build surface while printing based on the second topographic compensation map.

18. A three-dimensional printer, comprising: a three-dimensional printer head movable in an x-y plane, the three-dimensional printer head includes: a feed plate, a first feed assembly moveably affixed to the feed plate, wherein the first feed assembly includes a first extrusion nozzle,

22 a second feed assembly moveably affixed to the feed plate, wherein the second feed assembly includes a second extrusion nozzle, a cam rotatably mounted to the feed plate, configured to move the first feed assembly and second feed assembly relative to each other, at least one of a first sensor and a first sensor trigger mounted to the first feed assembly and the other of the first sensor and first sensor trigger mounted to the feed plate, and at least one of a second sensor and a second sensor trigger mounted to the second feed assembly and the other of the second sensor and the second sensor trigger mounted to the feed plate; a support bed, including: a support surface, wherein the support bed is movable relative to the printer head along a z-axis, and a build plate removably positioned on the support surface; and a controller, wherein the controller includes executable code to: measure a first position of the build surface in the z-axis at a first number of points on the build surface when the build surface is pressed against a first nozzle affixed to a printer head; create a first topographic compensation map based on the position of the build surface in the z-axis measured at the first number of points on the build surface; and store the first topographic compensation map in non-transient memory included in the three-dimensional printer for reference during printing with the first extrusion nozzle.

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19. The three-dimensional printer of claim 18, wherein the controller further includes executable code to print with the first extrusion nozzle; and adjust a printing distance between the first extrusion nozzle and the build surface while printing based on the first topographic compensation map.

20. The three-dimensional printer of claim 18, wherein the controller further includes executable code to measure a second position of the build surface in the z-axis at a second number of points on the build surface when the build surface is pressed against the second extrusion nozzle, one of a) create a second topographic compensation map, or b) augment the first topographic compensation map using the measured second position at the second number of points; and adjusting a printing distance between the second extrusion nozzle and the build surface while printing with the second extrusion nozzle.

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