AU2022200413A1

AU2022200413A1 - Printer head for 3D printer and methods of using same

Info

Publication number: AU2022200413A1
Application number: AU2022200413A
Authority: AU
Inventors: David Maxwell Ellis
Original assignee: Bodd Tech Pty Ltd
Current assignee: Bodd Technologies Pty Ltd
Priority date: 2021-01-21
Filing date: 2022-01-21
Publication date: 2022-08-04

Abstract

A printer head for a 3D printer is disclosed. The printer head comprises a heat block comprising a body, the body defining a filament inlet, a filament outlet, and a filament pathway connecting the filament inlet and the filament outlet. The heat block is configured to melt a filament of a printing material in the filament pathway. The filament pathway comprises at least one arcuate portion. 3/7 z 160 y Y 210 37513 1336 370 395 352 340, 350 312, 314 300, 310 230 300, 390 - 392, 394 322, 324 340, 360 362 380 375 300, 330 332, 334 300, 320 220 136 Fig.3A

Description

3/7

z

160 y

Y 210 37513

370 395

352

340, 350

312, 314

300, 310

230

300, 390 1336 - 392, 394

322, 324 340, 360 362

380 375

300, 330

332, 334

300, 320

220 136

Fig.3A

"Printerhead for 3D printer and methods of using same"

Technical Field

[0001] The present disclosure relates to devices for additive manufacturing processes, also known as 3D printing. Embodiments relate to a 3D printer, and in particular, to the "hot end" of the 3D printer. The present disclosure also relates to methods of using said devices.

Background

[0002] Additive manufacturing is the manufacture of parts through the deposition of molten material. Molten material is deposited on a platform below the printer head, and progressively added in layers to produce a three-dimensional part.

[0003] Before production, the part is modelled using computer aided design (CAD) modelling software. This model may then be interpreted by a 3D printer for production. A filament of raw material is fed into the 3D printer, which melts the filament in its "hot end". The molten filament material is deposited by the 3D printer onto the printer's platform and is progressively built up in layers as previously described.

[0004] Advantageously, the molten material is only deposited where it is needed, meaning there is minimal wastage of the raw material. The layered production process also allows intricate parts to be produced with high precision. These aspects of the 3D printing process enable the production of parts without the need for bespoke moulds or tools.

[0005] However, the size of parts able to be produced is limited by the size of the 3D printer and its platform. Other limitations of the 3D printing process include restrictions on the types of materials used, and the speed of the printing process.

[0006] It is desired to address or ameliorate one or more shortcomings of present 3D printers, or to at least provide a useful alternative thereto.

[0007] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

[0008] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Summary

[0009] Some embodiments relate to a printer head for a 3D printer, the printer head comprising: a heat block comprising a body, the body defining a filament inlet, a filament outlet, and a filament pathway connecting the filament inlet and the filament outlet; wherein in the heat block is configured to melt a filament of a printing material in the filament pathway; and wherein the filament pathway comprises at least one arcuate portion.

[0010] The heat block may further comprise abase, wherein the base and the body define the filament pathway. The base and the body may be separable. The body and the base may comprise respective wall surfaces which define thefilament pathway. The filament inlet may be disposed in the body, and the filament outlet may be disposed in the base.

[0011] The at least one arcuate portion may comprise a plurality of separate arcuate portions. In embodiments comprising said plurality of separate arcuate portions, the plurality of arcuate portions include successive arcuate portions. The filament pathway may further comprise at least one linear portion connecting two of the plurality of arcuate portions.

[0012] In some embodiments, the at least one arcuate portion includes a first arcuate portion configured to guide the filament along a first arcuate path. The first arcuate path may be arcuate in a first reference plane. The at least one arcuate portion may further include a second arcuate portion configured to guide the filament along a second arcuate path. The second arcuate path may be arcuate in a second reference plane.

[0013] In some embodiments the at least one arcuate portion further includes a third arcuate portion configured to guide the filament along a third arcuate path. The third arcuate path may be arcuate in a third reference plane. At least two of the first, second, and third reference planes may be angled relative to each other. The filament pathway thereby follows a three dimensional path, such as a coil or loop shape. This allows the filament pathway to have a greater length compared to a filament pathway that goes in a straight line from the filament inlet to the filament outlet.

[0014] The first reference plane maybe coplanar with a straight reference line connecting the filament inlet and the filament outlet. Alternatively, the first reference plane may be angled relative to a straight reference line connecting the filament inlet and the filament outlet.

[0015] The filament pathway may comprise a reversal-of-direction portion between the filament inlet and the filament outlet. The reversal-of-direction portion may comprise a U turn or have a generally horseshoe shape. The reversal-of-direction portion may help to reduce ooze of the filament (of printing material, when at least partially melted) from the heat block.

[0016] Some embodiments relate to a printer head for a 3D printer, the printer head comprising: a heat block defining an arcuate filament pathway connecting a filament inlet to a filament outlet, the heat block configured to melt a filament of a printing material in the filament pathway; wherein the heat block comprises successive heating zones positioned along the filament pathway; and wherein each heating zone has respective heating elements.

[0017] The heating zones may comprise an intermediate heating zone positioned between an initial heating zone and a final heating zone. The initial and final heating zones may be adjacent. The initial heating zone may be configured to heat the filament to its glass transition temperature. The intermediate heating zone may be configured to heat the filament from its glass transition temperature to its melting temperature. The final heating zone may be configured to heat the filament to maintain its melting temperature. The initial and final heating zones may be heated by the same heating element.

[0018] The heating elements may include removable cartridge heaters. The heat block may comprise an inlet heater adjacent to the filament inlet, and an outlet heater positioned adjacent to the filament inlet and the filament outlet.

[0019] The length of the filament pathway measured from the filament inlet to the filament outlet may be between about two to about four times the length of a straight reference line connecting the filament inlet and the filament outlet. The length of the filament pathway measured from the filament inlet to the filament outlet may be approximately three times the length of a straight reference line connecting the filament inlet and the filament outlet.

[0020] Some embodiments relate to a 3D printer comprising the printer head as previously described.

[0021] Some embodiments relate to a method of printing a 3D object, the method comprising causing a filament of a printing material to travel along a filament pathway defined by a lumen of a printer head, the filament pathway being arcuate in a first reference plane.

[0022] The method may further comprise causing the filament to travel along a subsequent arcuate portion of the filament pathway. The subsequent arcuate portion may be arcuate in a second reference plane. The method may further comprise causing the filament to travel along a U turn or generally horseshoe shaped portion of the filament pathway.

[0023] Some embodiments relate to a method of printing a 3D object, the method comprising: melting a solid filament in a filament pathway to produce a molten filament, wherein the solid filament is solid toward an inlet end of thefilament pathway, and wherein the solid filament is melted and becomes molten towards an outlet end of the filament pathway; directing, along a first part of the filament pathway connecting a filament inlet to a filament outlet, the melted filament to flow with gravity so that the solid filament exerts a pressure on the melted filament; and directing, along a second part of the filament pathway, the melted filament to flow against gravity to reduce the pressure on the molten filament prior to passing through the outlet.

[0024] The method may further comprise forcing the melted filament along the filament pathway towards the filament outlet; and retracting the solid filament to reduce the flow of the melted filament along thefilament pathway.

Brief Description of Drawings

[0025] Embodiments are described in further detail below, by way of example, with reference to the accompanying drawings, in which:

[0026] Fig. 1 is a schematic diagram showing a 3D printer in communication with a computer and a power source. The 3D printer may comprise a hot end and a cold end The hot end comprises a printer head with an arcuate filament pathway, according to some embodiments;

[0027] Fig. 2 is a section view of the printer of Fig. 1, taken along the line A-A as marked. In particular, Fig. 2 shows a cross section through the hot end of the printer head to show part of the arcuate filament pathway, according to some embodiments; and

[0028] Fig. 3A is a perspective view of a heat block of the printer head of Figs. 1 and 2, wherein the heat block defines the arcuate filament pathway, according to some embodiments;

[0029] Fig. 3B is the same perspective view of a heat block as Fig. 3A, showing reference lines for clarity;

[0030] Fig. 4A is afirst exploded perspective view of the heat block of Fig. 3, according to some embodiments;

[0031] Fig. 4B is a second exploded perspective view of the heat block of Fig. 3, as viewed from a reverse angle to that shown in Fig. 4A, according to some embodiments;

[0032] Fig. 5 is a perspective view of the arcuate filament pathway of Fig. 3, according to some embodiments.

Detailed Description

[0033] The present disclosure relates to devices for additive manufacturing processes, also known as 3D printing. Embodiments relate to a 3D printer, and in particular, to the "hot end" of the 3D printer. The present disclosure also relates to methods of using said devices.

[0034] A 3D printer comprises a "cold end" connected to the hot end via a passage called a heat break. The cold end includes various parts and structures which operate at a much lower temperature than the hot end. For example, the cold end comprises a mechanism to feed a filament of a printing material through the heat break to the hot end. The hot end is configured to melt the filament and guide the filament towards a nozzle for deposition on the platform. The filament may be partially melted or molten (fully melted) in the hot end.

[0035] Embodiments of the present disclosure include a 3D printer head for use in the hot end of a 3D printer. Embodiments of the printer head comprise a heat block for melting the filament. The heat block defines a filament pathway, a filament inlet, and a filament outlet, wherein the filament pathway connects the filament inlet to the filament outlet. The filament inlet may be the point at which the filament enters the heat block (for example, from the heat break), and the filament outlet may be the point at which the filament exits the heat block and proceeds towards the nozzle. The nozzle may be connected to and be in fluid communication with the filament outlet. A pressure on the filament in the filament pathway promotes the flow of thefilament toward the nozzle.

[0036] The printer head is positioned directly above the platform so that the molten filament of printing material falls from the nozzle onto the platform. The filament pathway conventionally follows a linear path (i.e. a straight line) from the filament inlet to the filament outlet. Accordingly, the length of the conventional linear filament pathway determines the height of the printer head, which in turn determines the height of the 3D printer.

[0037] Embodiments of the 3D printer head provide a filament pathway comprising at least one arcuate portion, or a series of arcuate portions. Examples may include a loop shaped portion, horseshoe shaped portion, "S" shaped portion, spiral portion or helical portion or portions. In having such arcuate portion(s), the length of the filament pathway (as measured from the filament inlet to the filament outlet) can be made longer than the length of a generally linear filament pathway provided by a printer head of similar height.

[0038] In 3D printer heads having a linear filament pathway, reducing the height of the printer head shortens the length of the filament pathway. A shorter filament pathway means the heat block has less time to heat the filament to transition from the ambient temperature (where it is hard and slightly brittle) to a melting temperature at which the filament material becomes a very viscous liquid, ready for printing. To allow more time to transition the filament from ambient to melting temperature, the speed of the filament passing through the filament pathway is reduced. This slows the print speed down, which can be problematic or impracticable for applications requiring high printing speeds. Alternatively, to avoid slowing the print speed, the temperature of the heat block can be increased so that the filament reaches the desired printing temperature sooner.

[0039] High speed printing is measured in volume per minute. By way of example, a high print speed would be a speed around 7000 mm3 /min and above. In comparison, a typical home consumer-level 3D printer would print at a flow rate of approximately 800 mm 3 /min, with a high-end home consumer-level 3D printer capable of printing around 1500 mm 3 /min. Some embodiments of the 3D printer head are capable of high speed printing. In some embodiments, the 3D printer head has a print speed in the range of approximately 6000 mm 3 /min to 10000 mm3 /min. The print flow rates of some embodiments of the 3D printer head are around 9000 mm3/min.

[0040] However, increasing the temperature of the heat block must be done carefully, as factors such as the type of filament material, size of the filament, heater capacity, and the thermal properties of the heat block must all be considered when determining the effect of increased heat on print speed. The relationship between heat and printing speed is not linear, and obtaining a faster print speed (with the same quality) is not as simple as increasing the temperature. Heat losses from the heat block also have to be considered when increasing the temperature. When the filament enters the heat block from the cold end, the filament is at much a lower temperature than the heat block, and thus may have a cooling effect on the heat block. Heat loss to the environment is also a factor, and depends on the ability of the heat block to retain heat. For example, a heat block with low weight is more likely to lose heat compared to one with greater thermal mass. It would also not be feasible to slow the printing speed and have lower heating temperatures, as this would result in insufficient or inconsistent melting of the filament, and may lead to a printed part being printed at different temperatures, which would cool and shrink at different times and possibly result in structural defects.

[0041] Furthermore, increasing the temperature of the heat block increases the risk of overheating or burning the filament, which may adversely affect the strength and properties of the printing material, and risk contaminating the printed part with burnt filament pieces. An overheated filament may also be too runny, which makes controlling the flow difficult, as excess filament may drip or ooze from the nozzle. If the filament is too runny, it may therefore may not cool and set properly when deposited on the platform, resulting in a 3D printed part that does not resemble the intended design. For example, as the material cools, it shrinks; the risk of shrinkage, sagging, or drooping of the printed part is greater as it cools from a higher temperature.

[0042] In comparison, embodiments of the 3D printer head disclosed herein have a longer filament pathway, which for a given printer speed allows more time for melting/transitioning the filament from ambient to its melting temperature. Embodiments of the 3D printer head having a longer filament pathway may operate at a higher print speed as the longer filament pathway gives more time for the filament to get up to the required temperature. The longer filament pathway also means that the melting/transition process can be more gradual than a shorter filament pathway would otherwise allow. A more gradual melting process reduces the risk of overheating or burning the filament. A more gradual melting process also allows more time for the heat to fully penetrate the filament's thickness, thereby reducing the risk of inconsistent heating (such as the filament being correctly heated and melted on the outside but having an inside portion/core that is insufficiently heated or melted) which may result in blockages of the filament pathway or the nozzle.

[0043] Being a straight line, a linear filament pathway may thus be referred to as one dimensional (ID). An arcuate filament pathway may be referred to as two-dimensional (2D) or three-dimensional (3D), depending on the quantity and the orientation of the arcuate portions.

[0044] Fig. 1 shows an embodiment of a 3D printer 100 comprising a platform 110 and a printer head 120. The platform 110 is configured to receive molten filament material deposited from the printer head 120. The platform 110 and the printer head

120 are configured to move relative to each other. Some embodiments of the printer 100 may move the platform 110 in addition to (or instead of) moving the printer head 120 in one or more directions.

[0045] As shown, the printer 100 is a carriage-style printer comprising rails 102, 104 which allow movement of the printer head 120 along a Cartesian coordinate system. The rail 102 corresponds with the Cartesian X-axis (movement of the printer head 120 in a first horizontal direction), and the rail 104 corresponds with the Cartesian Z-axis (vertical movement). Fig. 1 is thereby a view of the printer 100 in the XZ reference plane.

[0046] Some embodiments of the printer 100 may additionally include a third rail (not shown), aligned to correspond with the Cartesian Y-axis to permit movement of the printer head 120 in a second horizontal direction. In the Cartesian coordinate system, the X, Y, and Z reference axes are perpendicular to each other. The XY reference plane, defined by the X and Y axes, is parallel with the platform 110.

[0047] The printer 100 may comprise a motor or actuator (not shown) for moving the printer head 120 along the rails 102, 104. The printer head 120 may comprise a carriage (not shown) which has wheels or pulleys to engage the rails 102, 104. In some embodiments, the carriage may have toothed wheels which engage with corresponding teeth on the rails 102, 104, such as a rack and pinion type arrangement.

[0048] Some embodiments of the printer 100 may move the printer head 120 using other mechanisms, such as belts, electric arms, and/or pulleys instead of (or in addition to) using the rails 102, 104. Some embodiments of the printer 100 may alternatively use a Polar coordinate system to manipulate the position of the printer head 120. The choice of mechanism and coordinate system to move the printer head 120 is independent of the construction of the printer head 120.

[0049] Continuing to refer to Fig. 1, in some embodiments the printer head 120 comprises a controller 106. The controller 106 may be configured to receive instructions from a computer 108, such as instructions to print the CAD model. For example, the computer 108 may provide instructions expressing the CAD model as an array of layers or slices, and the controller 106 interprets these instructions to print these layers in the appropriate sequence to form a printed part resembling the CAD model. In some embodiments, the printer head 120 comprises a cold end 130 and a hot end 140, separated by a heat break 135 (shown in phantom). The heat break 135 is designed to prevent or reduce heat transfer from the hot end 140 to the cold end 130. If too much heat travels into the cold end 130, it may cause the filament to expand and impede subsequent movement of the filament into the hot end 140. The heat break 135 may comprise a thin, tube-like structure to facilitate heat dissipation.

[0050] The cold end 130 may comprise a filament extruder 132. In some embodiments, the cold end 130 may comprise the filament extruder 132 and a filament guide 134. The filament extruder 132 receives a filament 136 of printing material (or if the optional filament guide 134 is present, receives the filament 136 via the filament guide 134), and then feeds and extrudes the filament 136 into the desired cross sectional shape and size. In some embodiments, the filament extruder 132 is a "direct drive" extruder, wherein the extruder 132 is mounted on the printer head 120. In some embodiments, the filament extruder 132 is a "Bowden type" extruder, wherein the extruder 132 is mounted on the frame of the printer 100. The filament guide 134 may be a tube which defines a lumen for receiving the filament 136. Part of the filament 136 is shown in the filament guide 134 to indicate the configuration. An example of a filament extruder 132 is the Bondtech QR extruder, which may be used in direct drive or Bowden type configurations. The printer head 120 may comprise a cooling system 122 which provides cooling and ventilation of the cold and/or hot ends 130, 140, as well as to the heat break 135. The cooling system 122 may comprise a fan and/or a heatsink. The heatsink may have fins to enlarge the surface area available for heat dissipation.

[0051] The hot end 140 comprises a nozzle 150 and a heat block 160. One such nozzle may be the "E3D Super Volcano" nozzle. In some embodiments, a custom nozzle is used instead depending on the application requirements. The heat block 160 is configured to melt the filament 136 in the filament pathway. The heat block 160 may melt the filament 136 by heaters (such as shown in Figs. 3 to 5). The printer 100 and the heaters are powered by a power source 162. Control of delivery of power from the power source 162 may be controlled by the controller 106. The controller 106 may use a pulse width modulation (PWM) process to control delivery of power from the power source 162. The heat block 160 may be cooled at least in part by the cooling system 122. The cooling system 122 may be controlled by the controller 106.

[0052] Fig. 2 is across section of the printer 100 in the YZ reference plane, and more clearly shows the connection between the cold end 130, the heat break 135, and the hot end 140. The heat block 160 comprises a structure or body 200 that includes an inlet portion 210, and an outlet portion 220. The heat break 135 may be connected to the inlet portion 210, and the nozzle 150 may be connected to the outlet portion 220. The nozzle 150 is in fluid communication with the outlet portion 220.

[0053] The body 200 comprises a wall surface or a plurality of wall surfaces. The wall surface or plurality of wall surfaces may, alone or in combination with other parts of the body 200, define a filament pathway 230. For example, the heat block 160 may comprise a pipe or tube 200 having a wall surface which defines a lumen, wherein the lumen acts as the filament pathway 230. The filament pathway 230 connects the inlet portion 210 and the outlet portion 220. The filament pathway 230 is a passage or conduit which is configured to guide the filament 136 (whether solid, partially melted or fully melted) towards the nozzle 150. The filament 136 is configured to fill the filament pathway 230 so that no air bubbles or pockets are present. When the filament 136 is fully melted (molten), no air bubbles or pockets should be present. Air bubbles or pockets will cause an interrupted or inconsistent flow of the filament 136 through the nozzle 150, which will result in the printed part having areas where less or no filament 136 has been deposited. This may affect the appearance or strength of the printed part.

[0054] The body 200 may comprise various zones. These zones may correspond with zones of the heat block 160 having certain technical functions (for example, different zones may enable the heat block 160 to heat the filament 136 to different temperatures, or modify the cross-section of the filament 136). Each of the zones may be associated with different portions of the filament pathway 230. Each portion of the filament pathway 230 has a longitudinal direction or axis which collectively defines the path that the filament 136 follows as it moves through or along the filament pathway 230.

[0055] In operation of the printer 100, the filament 136 may move from the cold end 130, into the heat break 135, and into the hot end 140 via inlet portion 210. The filament 136 may then move through the filament pathway 230, where it is melted by the heat block 160, and exits the heat block 160 via the outlet portion 220. The nozzle 150 may be connected to the outlet portion 220 and may be in fluid communication with an outlet end of the filament pathway 230. The melted filament 136 may then pass through the nozzle 150 (exiting the hot end 140), where it may then be deposited onto the platform 110.

[0056] The size of the hot end 140 is determined by the length of the nozzle 150 and the height of the heat block 160. The height of the heat block 160 is determined by the distance between respective extremities of the inlet portion 210 and the outlet portion 220. This distance is related to the length of the filament pathway 230.

[0057] In conventional 3D printer head arrangements, the filament pathway is a direct, linear, straight path between the inlet and outlet portions of the heat block. This means that there is a proportional relationship between the length of the filament pathway and the height of the heat block; in other words, lengthening of the filament pathway causes a corresponding increase in the height of the heat block. For example, a 1cm lengthening of the filament pathway may result in a lcm increase in the height of the heat block.

[0058] In contrast, in some embodiments of the printer head 120, the filament pathway 230 takes a less direct (i.e. more circuitous) path to connect the inlet and outlet portions 210, 220. Accordingly, by the filament pathway 230 taking a circuitous path, the length of the filament pathway 230 can be increased without proportionally affecting the height of the heat block 160 in the manner previously described. For example, a lcm lengthening of the filament pathway 230 can be accommodated without an increase in the height of the heat block 160.

[0059] Lengthening the filament pathway 230 may allow more of the filament 136 to be accommodated in the heat block 160, which may thereby allow more of the filament 136 to be melted at the same time. A longer filament pathway 230 may allow a more gradual melting process of the filament 136, because for a given flow rate, the filament 136 has more time to be melted in comparison to a shorter filament pathway. A longer filament pathway 230 allows a more complete saturation of heat through the filament 136, and may allow a cooler printing temperature. Without a short filament pathway, there is no need to quickly heat the filament 136 with high temperature. This longer filament pathway 230 aids in the printability of the filament 136 for a better quality printed product, as shrinking during cooling is less pronounced, while allowing a higher print speed to be maintained. Extending the length of thefilament pathway 230 also reduces the need to increase the temperature to ensure that the filament 136 is heated to the correct temperature. Accordingly, this reduces the risk of overheating the filament, even in high printing speed applications. A cooler printing temperature also reduces the size of heatsinks and other cooling devices or systems 122 required to cool the printer head 120.

[0060] A shorter heat block 160 may allow the hot end 140 to be smaller, which may thereby allow more space between the nozzle 150 and the platform 110 for melted filament to be deposited. This may allow for larger objects and parts to be printed by the printer 100, in comparison to a printer with similar outer dimensions but with a larger hot end. A shorter heat block 160 may allow the hot end 140 to be more compact (i.e. less elongate), reducing the inertia and unwanted movement at the extremities of the heat block, such as at the tip of the nozzle 150. A smaller hot end 140 may allow faster manipulation of the printer head 120 for a given motor capacity. The smaller, more compact hot end 140 may also reduce the loads (weight and inertia) on the motor or actuator which drives the printer head 120. This reduces wear and tear on the motor or actuator, and may allow a smaller or less powerful motor or actuator to be used, which may therefore be quieter.

[0061] Figs. 3A and 3B each show a perspective view of the heat block 160, according to some embodiments. As previously described, the body 200 of the heat block 160 defines the filament pathway 230. In some embodiments, thefilament pathway 230 comprises at least one arcuate portion 300. The arcuate portion 300 guides the filament 136 along a curved path or paths. The arcuate portion 300 may comprise a plurality of arcuate portions 300, such as a first arcuate portion 310, a second arcuate portion 320, and a third arcuate portion 330. The curved path allows thefilament pathway 230 to take a less direct, more circuitous path to connect the inlet and outlet portions 210, 220.

[0062] The curved path(s) of the arcuate portion(s) 300 are defined by respective radiuses (radii). For example, the first arcuate portion 310 comprises a first curved path 312, wherein the first curved path 312 (shown in Fig. 3A as a dotted line) is defined by at least one radius, such as a first radius 314. Similarly, the second arcuate portion 320 may comprise a second curved path 322 (shown in Fig. 3A as a dotted line) defined by at least one radius, such as a second radius 324. Further, the third arcuate portion 330 may comprise a third curved path 332 (shown in Fig. 3A as a dotted line) defined by at least one radius, such as a third radius 334. In some embodiments, the curved paths 312, 322, 332 each comprise a plurality of curves, wherein each one of the plurality of curves is defined by respective radii. For example, the first curved path 312 may comprise two curves connected to each other, wherein each curve has its own radius.

[0063] In some embodiments, the plurality of arcuate portions may be successive, so that a filament in the filament pathway 230 can move from the first arcuate portion 310 directly into the second arcuate portion 320, and similarly from the second arcuate portion 320 directly into the third arcuate portion 330. In some embodiments, only some of the plurality of arcuate portions may be successive. For example, the first and second arcuate portions 310, 320 may be directly connected, but the third arcuate portion 330 may be connected to the second arcuate portion 320 by a non-arcuate portion of the filament pathway 230. The non-arcuate portion may comprise a linear (straight) portion or a plurality of linear portions.

[0064] In some embodiments, the filament pathway 230 comprises at least one linear portion 340. The at least one linear portion 340 may comprise a plurality of linear portions 340, such as a first linear portion 350 and a second linear portion 360. The linear portions 350, 360 guide the filament 136 along respective linear paths 352, 362 (shown in Fig. 3A as dotted lines). In some embodiments, the linear portions 350, 360 are collinear, or at least parallel. For example, as more clearly shown in Fig. 3B, the linear portions 350, 360 are parallel and offset from each other by a distance D. The linear portions 350, 360 (and linear paths 352, 362) may be offset in the XZ reference plane. The linear portions 350, 360 may alternatively be angled relative to each other depending on the curvature of the arcuate portion(s) 300. In some embodiments, the arcuate portions 300 are arcuate in different reference planes (i.e. the arcuate portions 300 may not be coplanar).

[0065] Continuing to refer to Fig. 3A, in some embodiments the heat block 160 defines a filament inlet 370 and a filament outlet 380. The filament inlet 370 may be a passage or aperture defined by the inlet portion 210, and the filament outlet 380 may be a passage or aperture defined by the outlet portion 220. The heat break 135 may connect to the inlet portion 210 at the filament inlet 370. The filament inlet 370 may define the start of the filament pathway 230. The end of thefilament pathway 230 may be defined by the filament outlet 380. The nozzle 150 may connect to the outlet portion 220 at the filament outlet 380 so as to be in fluid communication with the filament pathway 230.

[0066] When the filament 136 enters the filament pathway 230, it enters oriented in a first direction. As the filament 136 proceeds along the filament pathway 230, it follows the path set by the shape of the filament pathway 230. The filament pathway 230 comprises at least one arcuate portion 300, and so the filament 136 may change direction as a result of passing through the respective curvature(s) of the arcuate portion(s) 300. The filament 136 may continue in the first direction, or proceed in the changed direction, as a result of the respective linear portions 340.

[0067] For example, as the filament 136 proceeds along the first curved path 312, the filament 136 is progressively oriented along (or collinear with) various tangents to the first curved path 312. Each tangent is perpendicular to the respective radius(es) of the curved path(s). Each arcuate portion 300, being curved, therefore has a plurality of linear directions equivalent to each of these tangents to the curved paths. In some embodiments, the at least one arcuate portion 300 is arcuate in at least one reference plane, and the at least one reference plane is angled relative to a straight, imaginary reference line 375 connecting the filament inlet 370 and the filament outlet 380. For example, as shown in Fig. 3A, the at least one arcuate portion 300 (firstarcuate portion 310) is arcuate in the YZ reference plane. The second arcuate portion 320 of arcuate portion 300 is arcuate in the XY reference plane. The reference line 375, shown as a dash-dot line, is in (coplanar with) the XZ reference plane. The XZ, XY, and YZ reference planes are perpendicular. In some embodiments, the arcuate portions 300 are only arcuate in the XZ reference plane in which the reference line 375 lies, and the filament pathway 230 is arcuate in only two dimensions.

[0068] As shown in Fig. 3A, the filament 136 enters the filament pathway 230 via the filament inlet 370. The filament 136 may then proceed along the filament pathway 230, which comprises a combination of arcuate portions 300 (namely, first, second, and third arcuate portions 310, 320, 330) and linear portions 340 (namely, first and second linear portions 350, 360). As shown, the filament 136 proceeds in a first direction set by the orientation of the first linear portion 350. The aforementioned first direction is generally vertically downward (parallel with the vertical Z axis and perpendicular to the platform 110), so that the filament moves through the first linear portion 350 with the assistance of gravity.

[0069] The filament 136 then enters the first arcuate portion 310, wherein it proceeds along the first curved path 312. The first arcuate portion 310 and the first linear portion 350 are generally coplanar. As the filament 136 proceeds along the first curved path 312, it changes direction from the first direction. In general terms, the filament 136 proceeds at an angle relative to thefirst direction, ending up roughly perpendicular to the first (downward) direction by the end of the first curved path 312.

[0070] In the embodiment shown in Fig. 3A, the first arcuate portion 310 is connected to the second arcuate portion 320. Upon entering the second arcuate portion 320, the filament 136 proceeds along the second curved path 322, wherein the filament 136 again changes direction as it proceeds along the second curved path 322. In general terms, the filament 136 proceeds at an angle respective to the first curved path 312, ending up roughly facing back the way it entered the second curved path 322 (i.e. the second curved path 322 is generally a U turn). The second arcuate portion 320 may thus be referred to as a reversal of direction portion.

[0071] The first arcuate portion 310 and the second arcuate portion 320 are arcuate in different reference planes. The first arcuate portion 310 may be arcuate in a first reference plane, and the second arcuate portion 320 may be arcuate in a second reference plane. In various embodiments, the first and second reference planes may or may not be coplanar or parallel. As shown in the drawings, the second arcuate portion 320 is arcuate in a generally sideways direction compared to the first linear portion 350 (i.e. the second reference plane is approximately perpendicular to the first direction, to be parallel with the XY reference plane and platform 110). Being arcuate in a sideways (horizontal) direction allows the filament pathway 230 to increase in length without increasing the height of the heat block 160.

[0072] In the embodiment of the filament pathway 230 shown in Fig. 3A, the second arcuate portion 320 transitions into (and may be directly connected to) the third arcuate portion 330. The third arcuate portion 330 may be arcuate in a third reference plane. In some embodiments, the first, second and third arcuate portions 310, 320, 330 are arranged so that at least some of the first, second, and third reference planes are coplanar or parallel. In some embodiments, the first, second and third arcuate portions 310, 320, 330 are arranged so that at least some of the first, second, and third reference planes are not coplanar or parallel, and are angled relative to each other. In some embodiments, the first, second and third arcuate portions 310, 320, 330 are arranged so that at least some of the first, second, and third reference planes are angled relative to a straight, imaginary/reference line connecting the filament inlet 370 and the filament outlet 380.

[0073] As the filament 136 enters the third arcuate portion 330, it proceeds along the third curved path 332, wherein the filament 136 again changes direction as it proceeds along the third curved path 332. In general terms, the filament 136 proceeds at an angle respective to the second curved path 322, proceeding generally upwards (away from the nozzle 150) before doubling back on itself at a U turn 390 and entering the second linear portion 360. The U turn 390 may also be considered as a fourth arcuate portion 390, having a fourth curved path 392 of fourth radius 394, as shown in Fig. 3A as a dotted line. The U turn 390 may also be referred to as a reversal of direction portion. Upon leaving the U turn 390, the filament 136 then enters the second linear portion 360, where it proceeds generally downward with the assistance of gravity to exit the nozzle 150.

[0074] By going upwards (via the third curved path 332) and then doubling back on itself (via the U turn 390) to go downwards again, the filament pathway 230 increases in length without increasing the height of the heat block 160. In this way, the end of the filament pathway 230 (denoted by filament outlet 380) can be at the same height (vertical position) in the heat block as the second arcuate portion 320.

[0075] The configuration shown in Fig. 3A is merely exemplary and various configurations of arcuate portions 300 and linear portions 340 (or arcuate portions 300 alone) are possible to provide the advantage of a longer filament pathway 230 that does not directly result in a corresponding increase in the height of the heat block 160.

[0076] For example, the filament pathway 230 may comprise a loop shaped, horseshoe shaped, "S" shaped, spiral or helical portion or portions. In some embodiments, the portion of the filament pathway 230 comprising the third arcuate portion 330 and the fourth arcuate portion (U turn) 390 is generally "S" shaped. To provide the advantage of a longer filament pathway 230 that does not directly result in a corresponding increase in the height of the heat block 160, these shapes would extend the length of the filament pathway 230 in a horizontal or sideways direction (substantially parallel to the platform 110). In this way, the height of the heat block 160

(measured in a vertical direction, substantially perpendicular to the platform 110) is not directly increased.

[0077] A longer filament pathway 230 allows more space (length) and time for melting the filament 136. This means that the melting process can be more gradual (and a comparatively higher print speed can be achieved) than a shorter filament pathway would otherwise allow. A more gradual heating and melting process reduces the risk of damaging (e.g. burning) the filament 136, which may affect its mechanical properties such as strength and brittleness. A cooler, lower temperature filament is less likely to excessively ooze or drip from the nozzle 150, and experiences reduced shrinkage as it cools. Melting is provided by one or more heaters in the heat block 160. In some embodiments, the body 200 of the heat block 160 defines at least one chamber 395. The at least one chamber 395 may be configured to receive heaters for heating the filament pathway 230. For example, the at least one chamber 395 may be positioned adjacent to the filament inlet 370 to heat the first linear portion 350 of the filament 136, with additional chambers 395 disposed through the heat block 160 adjacent to the filament pathway 230. The at least one chamber 395 may also receive the heaters' associated circuitry for connecting to the controller 106. The at least one chamber 395 may include an electrical connector or conductor (not shown) for connecting the heater 440 to the power source 162. For example, the electrical connector or conductor may be in the form of terminals which are connected to the power source 162 by an electric circuit.

[0078] The curvature of the filament pathway 230 is gradual (i.e. first, second, and third radii 314, 324, 334 are large) to facilitate the movement of meltedfilament through the filament pathway 230. In other words, an angle between adjacent portions of the filament pathway 230 is obtuse. If the filament pathway 230 has a sudden change in direction, such as a sharp turn or corner (i.e. a curve with small radii, or said adjacent portions are at an acute angle), it may increase the risk of the filament 136 getting stuck in the filament pathway 230 as it negotiates the sharp corner, particularly if the filament 136 is not fully melted (molten).

[0079] In some embodiments, such as Figs. 3A and 3B, the heat block 160 is a single piece, which may be 3D printed for example. In some embodiments, the heat block 160 is an assembly. Figs. 4A and 4B are exploded views of the heat block 160 as an assembly, as viewed from different perspectives in order to show various aspects of the heat block 160. In some embodiments, the body 200 further comprises a base 400 which attaches to the body 200. To facilitate the attachment of the body 200 and the base 400, the body 200 and the base 400 may comprise an attachment structure 402. The attachment structure 402 may comprise a flange 404 (or flanges 404) which defines at least one or more bolt or screw holes 406 for receiving corresponding one or screws or more bolts 408 (only one bolt shown for clarity) to securely attach the body 200 and the base 400. The bolt 408 may be a countersunk Torx bolt. Other forms of attachment may be possible to securely attach the body 200 and the base 400. For example, clasps may be used to attach the body 200 and the base 400. In some embodiments, the flange 404 defines one or more grooves or slots configured to receive corresponding parts of the base 400, in the manner of a tongue and groove-type arrangement. In some embodiments, the attachment structure 402 may define a screw thread configured to engage with a corresponding screw thread of the base 400, so that the base 400 and the body 200 may be screwed together.

[0080] The base 400 may also comprise a wall surface 410 or a plurality of wall surfaces 410, in the same way that the body 200 comprises a wall surface 420 or a plurality of wall surfaces 420 (Fig. 4B). The wall surface(s) 410 and wall surface(s) 420 may define all or parts of thefilament pathway 230. In some embodiments, when the body 200 and the base 400 are attached to each other, the wall surfaces 410, 420 abut or adjoin each other so that respective surfaces of the wall surfaces 410, 420 in combination define the filament pathway 230. For example, when the filament pathway 230 is viewed in cross-section, the wall surfaces 410 and the wall surfaces 420 comprise separate surfaces that when adjoined, define the filament pathway 230 therebetween.

[0081] The filament pathway 230 may have varying cross-sections along the length of the filament pathway 230. The shape and area of the cross-sections may vary along the length of the filament pathway 230. For example, the filament pathway 230 may have a first cross-section of a first area in thefirst arcuate portion 310, a second cross-section of a second area in the second arcuate portion 320, and a third cross-section of a third area in the third arcuate portion 330. This may be to accommodate the varying amounts of thermal expansion of the heat block 160 and the filament depending on the temperature in each portion 300, and to reduce the likelihood of the filament becoming stuck in the filament pathway 230. In some embodiments, the filament pathway 230 has a circular cross-section. The filament pathway 230 may have an oval-shaped, a square shaped, star-shaped, or triangular-shaped cross-section, for example. The filament 136 has a cross-section dimension which is selected to substantially fill the cross-section of the filament pathway 230, so that little to no air bubbles or air pockets are present which may adversely affect the quality of the printed product.

[0082] The filament 136 may encounter friction with the filament pathway 230 as it moves along the filament pathway 230. In particular, when the filament 136 is at least partly melted (such as at or above its glass transition temperature, wherein it is slightly malleable), the filament 136 may expand and become slightly tacky. It is therefore advantageous for the filament pathway 230 to have a low friction surface in contact with the filament 136. In some embodiments, the heat block 160 defining the entire length of the filament pathway 230 has a low friction surface for contact with the filament 136. For example, the wall surfaces 410, 420 which define the filament pathway 230 may be highly polished to reduce their friction. By having a low friction surface or surfaces defining the filament pathway 230, the filament 136 may flow smoothly along the filament pathway 230. A filament pathway 230 with low friction surface(s) may reduce the likelihood of the filament 136 catching, snagging, or otherwise becoming stuck on any one of the wall surfaces 410, 420. In some embodiments, the wall surfaces 410, 420 which define the filament pathway 230 are coated with a non-stick or low friction coating to assist in the flow of thefilament 136 along the filament pathway 230. This may also assist the flow of filament 136 if expansion of the heat block 160 through heating were to constrict the diameter of the filament pathway 230. The filament pathway 230 may have a diameter in the range of approximately 1mm to 5mm. In some embodiments, the filament pathway 230 has a diameter of approximately 3.05 mm to 3.3 mm to accommodate filament 136 having a 3mm diameter. More specifically, the diameter of the filament pathway 230 may be 3.1 mm, or 3.2 mm.

[0083] At least some of the printer head 120 may be made from 3D printed components, such as the heat block 160. Some of the printer head 120 may be made from metal. This allows the printer head 120 to withstand high operating temperatures, for example, up to 300°C to 400°C. In some embodiments, the body 200 and the base 400 are made from 3D printed metal components. In some embodiments, the wall surfaces 410, 420 are made from 3D printed metal components. By 3D printing the printer head 120 (or the components thereof), this may lead to a more accurate part, a reduction in part counts, and/or raw material wastage compared to manufacturing by conventional methods such as by casting or milling. The various pieces of the heat block 160 may be assembled through the use of mechanical fasteners, such as bolts, screws or clasps.

[0084] The heat block 160 may further define or otherwise comprise a retainer 430 for supporting and positioning at least one heater 440 and its associated circuitry connecting it to the controller 106. The wall surfaces 410, 420 may define or act, at least in part, as the retainer 430 to support the at least one heater 440. The retainer 430 holds the at least one heater 440 in afixed position relative to thefilament pathway 230 so that the heater 440 is in a position to provide consistent heating over the length of the filament pathway 230. The retainer 430 may comprise multiple retainers each for supporting and positioning multiple heaters 440. The placement of the heaters 440 in relation to the filament pathway 230 may be more clearly seen in Fig. 5.

[0085] Continuing to refer to Figs. 4A and 4B, the at least one heater 440 is configured to heat the heat block 160 to melt the filament 136. Heat is transferred by conduction from the heater 440 through the heat block 160 and into thefilament pathway 230, where it then may be transferred into the filament 136. By having a filament 136 that is closely fitted within the filament pathway 230, there is less air between the filament 136 and the wall surfaces 410, 420 of the filament pathway 230.

Air acts as an insulator against heat, and if too much air is present between thefilament 136 and the wall surfaces 410, 420, heat transfer by conduction is affected, and heat transfer instead occurs by convection and radiation. In some embodiments, the at least one heater 440 comprises a first heater 450, a second heater 460, a third heater 470, and a fourth heater 480. The retainer 430 may comprise a first retainer 432 for the first heater 450, a second retainer 434 for the second heater 460, a third retainer 436 for the third heater 470, and a fourth retainer 438 for the fourth heater 480. The first retainer 432 may be a sleeve or chamber defined by the body 200.

[0086] The presence of multiple heaters (instead of a single, larger heater) allows the plurality of heaters to share the load of heating the multiple heating sections along the filament pathway 230. Multiple heaters may also distribute heating across a greater length of the filament pathway 230. Multiple heaters may also allow different amounts of heating in different portions of the filament pathway 230. In some embodiments, there are multiple separately configurable heat zones for the filament pathway 230 to provide improved control of the filament heating process. The temperature of each of the heaters 440 in these heat zones may be independently adjusted and controlled by the controller 106. Each of the heaters 440 may be dynamically adjusted in response to the temperature of the filament 136. For example, a specific one of heater 440 can be turned off or have its temperature output lowered if the temperature of thefilament 136 in a specific portion of the filament pathway 230 is found to be too high. Conversely, a specific one of heater 440 can have its temperature output increased if the temperature of the filament 136 in a specific portion of the filament pathway 230 is found to be too low. Multiple heaters may provide more deliberate control of the printing temperature, in particular by providing more control of the transitional process of the filament from ambient to full print temperatures. Multiple heaters may provide the ability to make adjustments as required, and also adds redundancy should one of the heaters 440 not be operating properly. The controller 106 may control the temperature of each of the heaters 440.

[0087] Each of the heaters 440 may have a power rating in the range of 20W to 60W. The heaters 440 may have power ratings which differ from each other. For example, some portions of the filament pathway 230 may require greater or lesser amounts of heat, and a less powerful heater may be smaller in size. In some embodiments, the heaters 440 all have the same power rating. Each of the heaters 440 may have a power rating around 40W. Each of the heaters 440 are connected to the power source 162 by respective electrical connectors or conductors (not shown). The electrical connectors or conductors may comprise terminals which engage with corresponding terminals on the heater 440 to connect the heater 440 to the power source 162, through an electric circuit. The controller 106 may apply the power from the power source 162 as required via a pulse width modulation (PWM) process and based on temperatures detected by at least one temperature sensor 442 associated with the heater(s) 440.

[0088] The number of heaters 440 may vary according to the length and geometry of the filament pathway 230. For example, a longer filament pathway 230 may require more of the heaters 440. A filament pathway 230 which coils on itself more may also allow a single heater 440 to cover a greater portion (or several of the heating zones 500) of the filament pathway 230. In some embodiments, the at least one heater 440 comprises four heaters 450, 460, 470, and 480. In some embodiments, there are one, two, or three heaters. In some embodiments, there are five or six heaters.

[0089] The number of heaters 440 may vary according to the type or construction of the heater 440. In some embodiments, the heater 440 is a coil type heater which wraps around the filament pathway 230. In some embodiments, a single heating filament or coil is wrapped along the length of the filament pathway 230 between the filament inlet 370 and the filament outlet 380.

[0090] Each heater 440 may have its own temperature sensor 442. The temperature sensor 442 is configured to allow accurate, live monitoring of the temperature of the filament 136, which may help to reduce overheating and burning of the filament 136, for example. The temperature sensor 442 may be located on the heater 440, or adjacent to the heater 440. The temperature sensor 442 may be a thermocouple. In some embodiments, the temperature sensor 442 may be a thermistor or a Resistance Temperature Detector (RTD), where the electrical resistance changes according to the temperature detected. The controller 106 may receive signals from each temperature sensor 442. In response, the controller 106 adjusts the power delivered to the heaters 440 to maintain the required temperature(s) of the filament 136. In some embodiments, the output of temperature sensor 442 is hardwired or otherwise electrically coupled to the controller 106. A plurality of the temperature sensors 442 may be distributed along the filament pathway 230, and/or at various points in the heat block 160 to allow monitoring of the heat block temperature and the filament temperature.

[0091] Turning now to Fig. 5, each of the heaters 440 may correspond to a specific heating zone 500. For example, the first heater 450 may correspond to a first heating zone 510, the second heater 460 may correspond to a second heating zone 520, the third heater 470 may correspond to a third heating zone 530, and the fourth heater 480 may correspond to a fourth heating zone 540. Each of the heating zones 500 correspond to portions of the filament pathway 230 in which the filament 136 is heated in specific conditions. The heating zones 500 may or may not be discrete heating zones which are physically separated or insulated from each other. The heat block 160 may also be insulated to improve retention of the heat generated by the heaters 440. For example, insulation may be present in or on the body 200 and the base 400. In the embodiment of the filament pathway 230 shown in Fig. 5, the lines 505, 515, 525, 535 shown dividing the heating zones 510, 520, 530, 540 are merely illustrative, with a gradual transition in temperature from one heating zone to the next heating zone.

[0092] In the first heating zone 510, the filament material undergoes a change from ambient (room) temperature to its glass transition temperature, at which the filament 136 turns from a hard state to a softer malleable state which can still maintain its general shape. The first heater 450 acts as a "pre-heater" to heat the filament 136 to be sufficiently malleable to navigate the arcuate portions 300 of the filament pathway 230, but remaining partially solid (i.e. is not fully liquid). Accordingly, the first heating zone 510 may be referred to as a conditioning zone.

[0093] By being partially solid, the filament 136 may be retracted through the filament pathway 230, such as by the filament extruder 132. Retracting of the filament

136 may be to control the filament movement (for example if the filament 136 is moving too quickly along the filament pathway 230), and to control oozing through the nozzle 150 (to reduce wastage and mess). For a filament 136 made from polylactic acid (PLA), the temperature of the PLA filament in the first heating zone 510 is typically in the range of 80°C to 140°C (176°F to 284°F). This raises the temperature of the filament 136 from ambient (room) temperature to the glass transition temperature of the material, which for PLA is around 60°C (140°F).

[0094] The filament 136 may be made from other materials, such as acrylonitrile butadiene styrene (ABS), thermoplastic polyurethane (TPU), or polyvinyl alcohol (PVA). For example, a filament 136 made from TPU may have a glass transition temperature of the TPU filament around 180°C (356°F). A TPU filament may have a printing temperature in the range of 21O0 C to 230°C (410°F to 446°F). A filament 136 made from ABS may have a glass transition temperature around 105°C (221°F). An ABS filament may have a printing temperature in the range of 240°C to 260°C (464°F to 500°F). A filament 136 made from PVA may have a glass transition temperature around 80°C (176°F). A PVA filament may have a printing temperature of approximately 215°C (419°F).

[0095] In the second heating zone 520, the filament material may transition from its glassy state (above the glass transition temperature) to a more fluid state (but below the temperature at which the material is fully melted). In this more fluid state, the filament material may be considered to be at its transition temperature, wherein the material is at its most expanded and most tacky state. The second heating zone 520 may accordingly be referred to as a transition zone. At the transition temperature, the filament 136 offers the most resistance to the filament extruder 132 or feed system pushing or feeding the filament into the filament pathway 230.

[0096] The second heater 460 increases the temperature of the filament 136 exiting the first heating zone 510. The second heater 460 may increases the temperature of the filament 136 so that the filament is more liquid, but is still partially solid. For a filament 136 made from PLA, the temperature of the PLA filament in the second heating zone 520 is typically in the range of 140°C to 170°C (284°F to 338°F).

[0097] In the third heating zone 530, the third heater 470 increases the temperature of the filament 136 exiting the second heating zone 520. The third heater 470 further melts the filament 136 and heats it to the final filament printing temperature (also known as the melting temperature). At this stage, the filament 136 is fully melted. The third heater 470 may be configured to keep the filament at the desired printing temperature, even at maximum printing volume and speed, by increasing the temperature as required. For a filament 136 made from PLA, the temperature of the PLA filament in the third heating zone 530 is typically in the range of 170°C to 200°C (338°F to 392°F).

[0098] In the fourth heating zone 540, the fourth heater 480 is configured to increase or at least maintain the temperature of the filament exiting the third heating zone 530. The fourth heater 480 acts as a "boost" heater to increase or maintain the temperature (and fluid consistency or viscosity) of the filament 136 as it heads towards the nozzle 150 for higher printing speeds. The presence of the fourth heater 480 reduces the risk of the filament 136 being insufficiently heated to the correct temperature and viscosity during high print speed operation, in the event that the filament 136 has not had enough time to be heated by the third heater 470.

[0099] While the use of the fourth heater 480 as a "boost" heater has been described in relation to higher printing speeds, the fourth heater 480 may also compensate for any general cooling of the filament 136, such as at slower printing speeds. For a filament 136 made from PLA, the temperature of the PLA filament in the fourth heating zone 540 is typically maintained in the range of 170°C to 200°C (338°F to 392°F), or at a temperature sufficient to keep the filament 136 fully melted and fluid without burning or degradation of the material.

[0100] In embodiments where the filament pathway 230 loops back on itself, such as shown in Fig. 5, the fourth heater 480 (or "boost" heater 480) may be configured to be arranged across both the first and fourth heating zones 510, 540. In this way, the fourth heater 480 can provide a boost to the heating of the filament 136 as it approaches the second heating zone 520, wherein the filament 136 transitions between its glass transition temperature and the melting temperature. The fourth heater 480 can then boost (or at least maintain) the temperature of the filament 136 as it heads towards the nozzle 150.

[0101] In some embodiments, each one of the heaters 440 maybe in the form of individual cartridges. This may permit them to be removed without removal of the entire printer head 120 or heat block 160. Avoiding or reducing the need to remove or separate the hot end 140 from the cold end 130 may improve the ease of maintenance and reparability of the printer 100.

[0102] The length of the filament pathway 230 maybe measured from the filament inlet 370 to the filament outlet 380. In some embodiments, the length of the filament pathway 230 is between 100mm and 200mm. In some embodiments, the length of the filament pathway 230 is approximately 169mm. The length of the filament pathway 230 may be typically around 2 to 4 times longer than similarly-sized printer heads available on the market. Some heat blocks on the market are around 10mm to 20mm in length, which results in less heating space (length) and time to heat the filament to the required temperature. In some embodiments, the length of the filament pathway 230 is around three times longer than similarly-sized printer heads available on the market. The cumulative length of the heating zones 510, 520, 530, 540 may be between 50% to 100% of the length of the filament pathway 230.

[0103] The combination of a longer filament pathway 230 having arcuate portions 300, and heating the filament 136 with multiple heaters 440, reduces the risk of burning or overheating the filament 136. A longer filament pathway 230 allows more gradual heating at a lower temperature, whereas a shorter filament pathway necessitates more rapid heating at a higher temperature to sufficiently melt the filament 136 before it exits the filament pathway. The lower heater temperatures allows for a better quality printed product as the deposited material is less likely to shrink under cooling (given the lower printing temperature) and is less likely to be too runny, which would cause sagging.

[0104] Having multiple heaters 440 may provide more specific and accurate control of the heating of the filament 136. For example, the filament 136 can be consistently heated to specific temperature(s) over the full length of the filament pathway 230, so that there are few (if any) unintentionally cooler spots along thefilament pathway 230 where the heated filament 136 may unintentionally lose temperature. A filament 136 that is consistently heated (through its depth and along its length) allows for a better quality printed product as the deposited material is fully melted and (geometry of the printed part permitting) will generally cool at the same rate. A filament 136 that is consistently heated also allows for higher printing speeds, as the filament 136 does not need to spend as much time in the heat block 160 to reach the required temperature.

[0105] Another aspect of the filament 136 being too runny is the resultant ooze or drip of excess filament from the nozzle 150. If an excess of the filament 136 is deposited, the printed product is less likely to resemble the intended shape, with string like formations indicating where the filament 136 has oozed and cooled. The oozed excess filament is wasted filament material that could otherwise have been used for the part.

[0106] Controlling ooze is particularly important in high speed printing applications, as printing at high speed requires a larger diameter nozzle to get the necessary filament throughput (compared to lower speed printing applications, where a smaller diameter nozzle can be used). Excess oozing or dripping of melted filament, particular with a larger diameter nozzle, can adversely affect the quality and accuracy of the printed part. In some embodiments, the nozzle 150 may have an outlet diameter in the range of approximately 1 mm to 3 mm. The nozzle 150 may have an outlet diameter of approximately 1.4 mm to 1.6 mm. Outlet diameters in the range of approximately 1.4 mm to 1.6 mm are suitable for a 3 mm diameterfilament 136.

[0107] Ooze maybe controlled by the lower heater temperatures, as well as the U turn 390. As described previously in relation to Figs. 4A and 4B, the U turn 390 guides the filament 136 upwards (away from the nozzle) before it proceeds downwards towards the nozzle 150 for deposition on the platform 110. By guiding the meltedfilament 136 upwards away from the nozzle 150 (against gravity) prior to exiting the filament pathway 230 via the filament outlet 380, there is a reduced amount of melted filament 136 directly above the nozzle 150. Specifically, there is a reduced amount of melted filament 136 in the second linear portion 360. Consequently, there is a lesser amount of melted filament 136 available to ooze or drip out of the nozzle 150.

[0108] The reduced amount of melted filament directly above the nozzle 150 reduces the weight or backpressure exerted on the "head end" of the filament 136 (the portion of the filament 136 in the filament pathway 230 about to pass through the filament outlet 380 and enter the nozzle 150 for deposition) by the rest of the filament 136. The backpressure, which promotes the flow of the filament 136 towards the nozzle 150, would be generally limited to the portions of the filament pathway 230 between the filament inlet 370 and the U turn 390. The backpressure may also be distributed over the length of the filament pathway 230, allowing compression of the filament 136 to occur between the cold zone and the nozzle exit. Consequently, there is a lesser amount of backpressure available to force oozing of the melted filament 136 from the second linear portion 360 out of the nozzle 150.

[0109] Ooze may also be controlled by retracting thefilament 136. Specifically, retraction involves reversing or pulling the filament 136 opposite to the direction of flow. By retracting or pulling the filament 136 away from the filament outlet 380, there is a reduced amount of melted filament 136 directly above the nozzle 150 (such as in the second linear portion 360), and therefore less melted filament 136 available to ooze or drip out of the nozzle 150. The amount of retraction required for the arcuate filament pathway 230 may be less than a linear filament pathway, as the U turn 390 helps to reduce the likelihood of ooze. As a result of heating the filament 136 to lower temperatures, the filament 136 is less likely to ooze, and therefore may not need to be retracted as frequently (or to the same amount) to control ooze. The reduced frequency and amount of retraction means that the printing process can be more expedient and/or efficient, as retraction takes time. Retraction of the filament 136 may also lead to extruder drive slippages, which may cause print fails i.e. a defective printed part. A longer filament pathway 230 allows more control of retraction by extending the length of the transition zone where the filament 136 transitions between its glass transition temperature and its melting temperature.

[0110] Embodiments of the printer 100 having a printer head 120 with a filament pathway 230 comprising arcuate portions 300 are able to accurately and quickly deposit large amounts of melted filament with minimal excess oozing. Consequently, these printers 100 may be used for 3D printing large parts. Examples of large parts may include parts ranging in size from 300 mm high to 2500 mm high (as measured along the Cartesian Z-axis from the platform 110). A large part made from PLA, ABS, TPU, or PVA may weigh approximately 1 kg to 10 kg total print weight.. These parts would otherwise take a long time to accurately print with conventional 3D printing techniques, as to have a high degree of accuracy the printing speed would have to be slowed to minimise ooze and avoid having to use a high temperature which may bum the filament.

[0111] The printer 100 maybe configured to receive instructions from the computer 108 to print the parts. The computer 108 may be configured to analyse a CAD model of the part and to convert it into a format which the printer 100 can interpret for printing the part. The CAD models may be derived from a 3D scan of an existing part, or designed from scratch in CAD software. In some embodiments, the controller 106 stores executable instructions to quickly print the part.

[0112] The printer 100 maybe used to print scale models of human body parts. The printer 100 may be used to print scale models of the full human body. The CAD models may be derived from a 3D scan of the user/wearer's body, or a specific part of their body. The scale models may be full scale, for example to use for designing and sizing prosthetics, apparel, clothing, or tools. This may allow custom-fitted prosthetics, apparel, clothing, or tools which are specific to a user's requirements, without the need for expensive machinery or moulds which are more cost effective for large scale manufacturing. Other applications may include printing large objects where it would be desirable to have a high print speed due to the size of the printed part. For example, a large vase, or structural components for a chair, or covers for mechanical equipment could be made using the printer 100.

[0113] The full scale human body models maybe used to display clothing, like a mannequin. The full scale human body models may be used to design, size, and fit clothing that is custom to a wearer's body. In this way, a tailor may iteratively design and resize or refine the clothing through ongoing reference to the full scale model of the wearer's body, without the need for the wearer to be present.

[0114] When the 3D printed model is no longer required, it maybe disposed of or recycled depending on the material used. Embodiments of the printer 100 are configured to print parts using PLA, which is biodegradable. PLA can be printed to a thickness that is durable and rigid enough to be used for the purpose of a full scale human body model, for example. Other materials include ABS, TPU, PVA. Some embodiments of the printer 100 can accommodate temperatures up to 300°C to 400°C. For materials requiring higher temperatures, components of the heat block 160 can be upgraded, for example by using 60W heaters instead of 40W heaters.

[0115] The combination of the printer 100 and the software increases the speed of the 3D printing process. A 3D print typically of a full-scale human can take as much as 24 hours on a typical 3D printer. With the combination of software and hardware, the print times can be reduced to less than 10 hours. The lower printing temperatures provide greater reliability and quality of the print compared to conventional printing techniques relying on higher printing temperatures to compensate for shorter filament pathways. The printing temperature may be up to 40°C less than conventional temperatures, for example.

[0116] In some embodiments, a method of using the printer 100 comprises the steps of causing a filament of a printing material to travel along at least one arcuate path 300 of a lumen of a printer head 120. The at least one arcuate path 300 may comprise a first arcuate path, such as the first curved path 312 defined by the first arcuate portion 310. The filament may then travel along a second arcuate path, such as the second curved path 322 defined by the second arcuate portion 320. The first and second paths 312, 322 may be arcuate in separate reference planes, such as a first reference plane and a second reference plane respectively, which may be angled relative to each other.

[0117] The method may further comprise directing the melted filament to flow from an inlet portion of the filament pathway. In this way, the portion of thefilament towards the inlet exerts a pressure on the portion of the filament towards the outlet, creating backpressure which encourages the flow of the filament towards the outlet. The flow may be assisted by gravity, depending on the orientation of the filament pathway. The method may further comprise the step of subsequently directing the filament to flow against gravity before it flows towards the nozzle, such as via a U turn 390, to reduce the pressure on the filament prior to passing through the outlet.

[0118] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

CLAIMS:

1. A printer head for a 3D printer, the printer head comprising: a heat block comprising a body, the body defining a filament inlet, a filament outlet, and a filament pathway connecting the filament inlet and the filament outlet; wherein in the heat block is configured to melt a filament of a printing material in the filament pathway; and wherein the filament pathway comprises at least one arcuate portion.

2. The printer head of claim 1, wherein the at least one arcuate portion comprises a plurality of separate arcuate portions.

3. The printer head of claim 1 or claim 2, wherein: the at least one arcuate portion includes a first arcuate portion configured to guide the filament along a first arcuate path, the first arcuate path being arcuate in a first reference plane.

4. The printer head of claim 3, wherein the at least one arcuate portion includes a second arcuate portion configured to guide the filament along a second arcuate path, the second arcuate path being arcuate in a second reference plane.

5. The printer head of claim 4, wherein the at least one arcuate portion includes a third arcuate portion configured to guide the filament along a third arcuate path, the third arcuate path being arcuate in a third reference plane.

6. The printer head of claim 5, wherein at least two of the first, second, and third reference planes are angled relative to each other.

7. The printer head of any one of claims 3 to 5, wherein thefirst reference plane is coplanar with a straight reference line connecting the filament inlet and the filament outlet.

8. The printer head of any one of claims 3 to 5, wherein the first reference plane is angled relative to a straight reference line connecting the filament inlet and the filament outlet.

9. The printer head of claim 2, wherein the plurality of arcuate portions include successive arcuate portions.

10. The printer head of claim 2, wherein the filament pathway further comprises at least one linear portion connecting two of the plurality of arcuate portions.

11. The printer head of any one of the preceding claims, wherein the filament pathway comprises a reversal-of-direction portion between the filament inlet and the filament outlet.

12. The printer head of claim 11, wherein the reversal-of-direction portion comprises a U turn or has a generally horseshoe shape.

13. The printer head of any one of the preceding claims, wherein the heat block further comprises a base, wherein the base and the body define the filament pathway.

14. The printer head of claim 13, wherein the base and the body are separable.

15. The printer head of claim 13 or claim 14, wherein the body and the base comprise respective wall surfaces which define the filament pathway.

16. The printer head of any one of claims 13 to 15, wherein the filament inlet is disposed in the body, and the filament outlet is disposed in the base.

17. A printer head for a 3D printer, the printer head comprising: a heat block defining an arcuate filament pathway connecting a filament inlet to a filament outlet, the heat block configured to melt a filament of a printing material in the filament pathway; wherein the heat block comprises successive heating zones positioned along the filament pathway; and wherein each heating zone has respective heating elements.

18. The printer head of claim 17, wherein the heating zones comprise an intermediate heating zone positioned between an initial heating zone and a final heating zone, and wherein the initial and final heating zones are adjacent.

19. The printer head of claim 18, wherein the initial heating zone is configured to heat the filament to its glass transition temperature, the intermediate heating zone is configured to heat the filament from its glass transition temperature to its melting temperature, and the final heating zone is configured to heat the filament to maintain its melting temperature.

20. The printer head of claim 18 or claim 19, wherein the initial and final heating zones are heated by the same heating element.

21. The printer head of any one of claims 17 to 20, wherein the heating elements include removable cartridge heaters.

22. The printer head of claim 21, wherein the heat block comprises an inlet heater adjacent to the filament inlet, and an outlet heater positioned adjacent to the filament inlet and the filament outlet.

23. The printer head of any one of the preceding claims, wherein the length of the filament pathway measured from the filament inlet to the filament outlet is between about two to about four times the length of a straight reference line connecting the filament inlet and the filament outlet.

24. The printer head of claim 23, wherein the length of the filament pathway measured from the filament inlet to the filament outlet is approximately three times the length of a straight reference line connecting the filament inlet and thefilament outlet.

25. A 3D printer comprising the printer head of any one of the preceding claims.

26. A method of printing a 3D object, the method comprising causing a filament of a printing material to travel along a filament pathway defined by a lumen of a printer head, the filament pathway being arcuate in afirst reference plane.

27. The method of claim 26, further comprising causing the filament to travel along a subsequent arcuate portion of the filament pathway, the subsequent arcuate portion being arcuate in a second reference plane.

28. The method of claim 26 or 27, further comprising causing the filament to travel along a U turn or generally horseshoe shaped portion of the filament pathway.

29. A method of printing a 3D object, the method comprising: melting a solid filament in a filament pathway to produce a moltenfilament, wherein the solid filament is solid toward an inlet end of thefilament pathway, and wherein the solid filament is melted and becomes molten towards an outlet end of the filament pathway; directing, along a first part of the filament pathway connecting a filament inlet to a filament outlet, the melted filament to flow with gravity so that the solid filament exerts a pressure on the melted filament; and directing, along a second part of the filament pathway, the melted filament to flow against gravity to reduce the pressure on the molten filament prior to passing through the outlet.

30. The method of claim 29, further comprising: forcing the melted filament along the filament pathway towards thefilament outlet; and retracting the solid filament to reduce the flow of the melted filament along the filament pathway.

31. The steps, features, integers, compositions and/or compounds disclosed herein or indicated in the specification of this application individually or collectively, and any and all combinations of two or more of said steps or features.