Stereolithography three-dimensional printer and corresponding methods

Abstract

A stereolithographic three-dimensional printer includes a vat for holding liquid photopolymer, a build plate, a light source and a controller configured to form layers of the part on the build plate by lowering the build plate into the liquid photopolymer, curing each layer with the light source, and pulling the build plate with the corresponding cured layer out of the vat using a pull force. The controller forms the layers of the part by: determining whether a pull force needed for the build plate to pull each layer of the part out of the vat after curing of the liquid photopolymer by the light source is above a predetermined pull force, forming the layer of the part as a single portion if the determined pull force is below the predetermined pull force, and forming the layer of the part as a plurality of portions if the determined pull force is above the predetermined pull force.

Description

STEREOLITHOGRAPHY THREE-DIMENSIONAL PRINTER ANDCORRESPONDING METHODSCross Reference to Related Application

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 283,002, filed on August 1, 2024, the disclosure of which is incorporated herein by reference in its entirety.Background

[0002] Current photopolymer-based 3D printers like SLA (stereolithography), MSLA (masked stereolithography) and DLP (digital light processing) printers print parts by forming successive layers, where each layer is a cross section of an object being printed. These printers typically utilize a vat having a thin film of material (a barrier layer) formed on the inner surface thereof. A material such as a photopolymer is inserted into the vat over the thin film. A first layer of the object is formed by lowering a build surface (substrate) into the photopolymer in the vat, and the photopolymer is exposed with a light source. A build platform then lifts the build surface with the cured first layer attached to the build surface from the vat. Successive layers of the object are formed by lowering the build surface with previous layers into fresh photopolymer in the vat with exposure of each layer by the light source. A pull force is applied by the build platform to pull the build surface with layer(s) of cured photopolymer out of the vat. The required pull force to pull the cured photopolymer layer(s) from the vat increases as the surface area of the cured photopolymer for each layer increases.

[0003] A total surface area of each layer when pulled from the build surface may generate high pull forces (Force = Pressure x Area). The larger the part the greater the pull force. Too large of a pull force may result in damage to the layer when pulled from the vat. This potential damage limits the size of a part that can be printed without damage and prevents these types of printers from scaling up to print larger parts.

[0004] It may be desirable to provide a stereolithography 3D printer that can produce larger pails without damage to the parts being produced from a large pull force.Summary

[0005] A stereolithographic three-dimensional printer and corresponding method of printing a part successively form layers of the part on a build plate. Liquid photopolymer is inserted into a vat, successive layers of the part are formed on a build plate by lowering the build plate into the liquid photopolymer, curing each layer with a movable light source to cure the layer, and pulling the build plate with the cured layer out of the vat using a pull force. Each of the layers of the part is formed by determining a pull force needed for the build plate to pull each respective layer of the part out of the vat after curing of the liquid photopolymer by the light source, comparing the pull force needed for the build plate to pull each respective layer of the part out of the vat to a predetermined pull force, if the pull force needed to pull the build plate with the cured layer of the part out of the vat is above the predetermined pull force, forming the respective layer of the part by forming a first portion of the respective layer on the build plate by curing the first portion of the respective layer with the light source, and pulling the build plate with the first portion of the respective layer out of the vat using a pull force below the predetermined pull force, and forming a second portion of the respective layer by inserting the build plate with the first portion of the respective layer into the vat, forming the second portion of the respective layer on the build plate adjacent to the first portion of the respective layer by curing the second portion of the respective layer with the light source and pulling the build plate with the cured first portion of the respective layer and with the cured second portion of the respective layer out of the vat using a pull force below the predetermined pull force, and wherein the pull force used to pull the respective layer out of the vat is below the predetermined pull force to prevent damage to the part.

[0006] A stereolithographic three-dimensional printer includes a vat for holding liquid photopolymer, a build plate, a light source and a controller configured to successively form layers of the part on the build plate by lowering the build plate into the liquid photopolymer, curing each layer with the light source, and pulling the build plate with the corresponding cured layer out of the vat using a pull force. The controller is configured to successively form each of the layers of the part by: determining whether a pull force needed for the build plate to pull each respective layer of the part out of the vat after curing of the liquid photopolymer by the light source is above a predetermined pull force, forming the respective layer of the part as a single portion if the determined pull force is below the predetermined pull force, and forming the respective layer of the part as a plurality of portions if the determined pull force is above the predetermined pull force,wherein the pull force used to pull the respective layer out of the vat is below the predetermined pull force to prevent damage to the part.

[0007] It will be appreciated that this summary is intended merely to introduce some aspects of the present methods, systems, and media, which are more fully described and / or claimed below. Accordingly, this summary is not intended to be limiting.Brief Description of the Drawings

[0008] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present teachings and together with the description, serve to explain the principles of the present teachings.

[0009] Figure 1 illustrates a schematic view of a stereolithographic three-dimensional printer according to various embodiments.

[0010] Figure 2 illustrates a schematic view of control electronics of a stereolithographic three- dimensional printer according to various embodiments.

[0011] Figure 3 illustrates aspects of a stereolithographic three-dimensional printer according to various embodiments.

[0012] Figure 4 illustrates a plurality of exposure portions used by a stereolithographic three- dimensional printer according to various embodiments.

[0013] Figure 5 illustrates a part being printed by a stereolithographic 3D printer according to various embodiments.

[0014] Figure 6 illustrates a part being printed by a stereolithographic 3D printer according to various embodiments.

[0015] Figure 7 illustrates a plurality of exposure portions used by a stereolithographic three- dimensional printer according to various embodiments.

[0016] Figure 8 illustrates a plurality of exposure portions used by a stereolithographic three- dimensional printer according to various embodiments.Detailed Description

[0017] A stereolithographic 3D (three-dimensional) printer configured to print large objects without damage from pull forces is described herein. In various embodiments, the stereolithographic 3D printer 100 is configured to keep a pull force when pulling curedphotopolymer forming layers of a part from a vat below a predetermined pull force to prevent damage to the part, as further described herein.

[0018] Figure 1 illustrates a schematic view of a stereolithographic 3D printer 100. In some embodiments, the stereolithography 3D printer 100 may include a user interface 102 and control electronics 104. The user interface 102 may be any type of user interface, such as a keyboard, a touchscreen or keypad, a voice control interface, etc. The control electronics 104 may be configured to control the stereolithographic printer to print objects by controlling various elements of the printer as further described herein.

[0019] Figure 2 illustrates further details of a possible configuration of the control electronics 102. As shown in this example, the control electronic 102 may be configured as a controller computing system 200 that includes a controller (computing device) 210 capable of communicating via a network, such as the Internet. In example embodiments, the computing device 210 may host programming and / or an application to carry out the functions as described herein. The computing device 210 may be configured to receive and / or obtain the data over communications interface 234, in some embodiments.

[0020] The computing device 210 may include a bus 214, a processor 216, a main memory 218, a read only memory (ROM) 220, a storage device 224, an input device 228, an output device 232, and a communication interface 234, as commonly used in printing devices, although other configurations of computing devices could be used.

[0021] Bus 214 may include a path that permits communication among the components of computing device 210. Processor 216 may be or include a processor, a microprocessor, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or another type of processor that interprets and executes instructions. Main memory 218 may include a random access memory (RAM) or another type of dynamic storage device that stores information or instructions for execution by processor 216. ROM 220 may include a ROM device or another type of static storage device that stores static information or instructions for use by processor 216. Storage device 224 may include a magnetic storage medium, such as a hard disk drive, or a removable memory, such as a flash memory.

[0022] Input device 228 may correspond to user interface 102 and may include a component that permits an operator to input information to device 210, such as a control button, a keyboard, a keypad, a voice control, or another type of input device. Output device 232 may also correspondto user interface 102 and include a component that outputs information to the operator, such as a light emitting diode (LED), a display, or another type of output device. Communication interface 234 may include any transceiver-like component that enables device 210 to communicate with other devices or networks. In some implementations, communication interface 234 may include a wireless interface, a wired interface, or a combination of a wireless interface and a wired interface. In various embodiments, communication interface 234 may receive computer readable program instructions from a network and may forward the computer readable program instructions for storage in a computer readable storage medium (e.g., storage device 224) or the computer readable program instructions could be manually loaded and stored.

[0023] System 200 may perform certain operations, as described in detail below. System 200 may perform these operations in response to processor 216 executing software instructions contained in a computer-readable medium, such as main memory 218. A computer-readable medium may be defined as a non-transitory memory device and is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire. A memory device may include memory space within a single physical storage device or memory space spread across multiple physical storage devices.

[0024] The software instructions may be read into main memory 218 from another computer- readable medium, such as storage device 224, or from another device via communication interface 234. The software instructions contained in main memory 218 may direct processor 216 to perform processes that will be described in greater detail herein. Alternatively, hardwired circuitry may be used in place of or in combination with software instructions to implement processes described herein. Thus, implementations described herein are not limited to any specific combination of hardware circuitry and software.

[0025] In some implementations, system 200 may include additional components, fewer components, different components, or differently arranged components than the components that are shown in FIG. 2.

[0026] The system 200 may be connected to a communications network (not shown), which may include one or more wired and / or wireless networks. Additionally, or alternatively, the network may include a local area network (LAN), a wide area network (WAN), a metropolitan network(MAN), the Public Switched Telephone Network (PSTN), an ad hoc network, a managed Internet Protocol (IP) network, a virtual private network (VPN), an intranet, the Internet, a fiber opticbased network, and / or a combination of these or other types of networks. In embodiments, the communications network may include copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and / or edge servers.

[0027] One of ordinary skill will recognize that the components, arrangement, and implementation details of the computing system 210 are examples presented for conciseness and clarity of explanation. Other components, implementation details, and variations may be used, including adding, combining, or subtracting components and functions.

[0028] The computing device 210 shown in FIG. 2 may be configured to cause the stereolithographic 3D printer 100 to functions as further described herein. In some examples, the stereolithographic 3D printer 100 may be configured to be operated remotely from a remote computing device, such as a laptop or desktop computer, a phone, a tablet or other electronic device (not shown) connected to the system 200 in a wired or wireless manner. The remote computing device, in some embodiments, may have an application stored therein configured to communicate with and control the system 200 as needed.

[0029] Figure 3 illustrates certain aspects of a stereolithographic 3D printer 300 in accordance with various embodiments. The stereolithographic 3D printer 300 may include a build plate 302, a vat (or container) 304 and a light source 306. The stereolithographic 3D printer 300 is configured to build or print objects. The stereolithographic 3D printer 300 is further configured to print larger objects than conventional stereolithographic 3D printers by reducing the pull forces for each layer of the object being printed, as further explained herein.

[0030] The build plate 302 may be configured to move up and down in the z direction above the vat 304. The build plate 302 may be connected to a build platform 303 that is configured to move the build plate 302 in the z direction in a conventional manner. Movement of the build plate 302 may be controlled by the computing device 210 controlling movement of the build platform 303, for example.

[0031] The light source 306 may be positioned below the vat 304 and may be configured to move in three dimensions, in the x direction, in the y direction and in the z direction. In Figure 3 the light source 306 is illustrated in various positions below the vat 304. The light source 306 is configured to move in the three dimensions in a conventional manner, such as under the control ofmotors, gyros, etc. Movement of the light source 306 may be controlled by the computing device 210.

[0032] The stereolithographic 3D printer 300 is configured to build a pail 308 by successively forming layers of the part 308 on a bottom side of the build plate 302. A first layer is built by lowering the build plate 302 into the photopolymer 310 in the vat 304. The light source 306 is then moved below the vat 304 to expose the photopolymer 310. The build plate 302 is then lifted out of the vat 304 to lift the cured photopolymer forming the first layer of part 308. Additional liquid photopolymer 310 is inserted into the vat 304 as needed and the build plate with the first layer is lowered into the vat to form the next layer of part 308. Successive layers of part 308 are thus formed until the part is completed.

[0033] Various embodiments of the stereolithographic 3D printer 300 may be configured to print larger parts than conventional stereolithographic 3D printers by maintaining the pull force required to pull the part 308 out of the vat 304 to a level to avoid damage to the part 308. The embodiments may have a maximum allowable pull force that may be preset. The maximum allowable pull force may be a maximum pull force that will not create damage to the currently being formed layer of the part 308 when the part is lifted out of the vat. In some embodiments, the maximum allowable pull force may be settable by a user. For example, the maximum allowable pull force could be set in a user interface. In some embodiments, the maximum allowable pull force to prevent damage to the part may be different for different materials used as the photopolymer. Entry of a type of photopolymer could be entered by a user via the user interface, in which case the system could have prestored maximum pull forces for different types of photopolymers, which could be accessed such as by the controller to determine the maximum allowable pull force for the entered type of photopolymer. The maximum allowable pull force may also be preset in the printer 300.

[0034] In various embodiments, the stereolithographic 3D printer 300 may be configured to determine a pull force that will be generated by a layer of the part 308 to be printed. If the pull force that will be generated by a layer of the part 308 is determined to be above the maximum allowable pull force, then the stereolithographic 3D printer will form the layer in more than one portion, with each portion being formed by a separate lowering of the build plate such that each portion of the layer is formed successively using a new portion of liquid photopolymer and a separate pulling of each of the cured portions of the polymer layer. This portioning of the layerallows a larger layer to be printed without exceeding the maximum allowable pull force for any pull, preventing damage to the layer of the part.

[0035] In some embodiments, when a size of a layer requires portioning of the layer due to a pull force that would be generated above a maximum allowable limit if the entire layer was cured in one instance, the system determines a number of portions to portion the layer into, the system determines the portions, and the light source 306 is successively moved to a different position 312, 314, 316, 318 corresponding to each portion to be formed. In this case, at each position of the light source 306, the system will expose the corresponding portion with the light source, and then pull the build plate out of the vat with the corresponding cured portion of the part. In some embodiments, the light source positions may be overlapped with each other to prevent any seams from being formed in the part.

[0036] In various embodiments, the stereolithographic 3D printer 300 may successively determine whether each layer of a part to be printed will exceed a maximum pull force if the entire layer is formed in one instance without portioning of the layer. In some embodiments, the pull force for a layer may be determined by the system based on a surface area of the layer. If the pull force for printing the entire layer in one instance is determined to be below the maximum allowable pull force, then the printer 300 may print that layer without portioning of the layer. If the pull force for printing the entire layer in one instance is above the maximum allowable pull force, then the printer 300 may print that layer with portioning of the layer. A pail may be printed with some of its layers being formed with portioning of the layer while other layers of the part are formed or printed without portioning of the layer.

[0037] In various embodiments, if a layer of the part is to be portioned, then the printer 300 may divide an area to be exposed into two or more exposure portions. After exposure by the light source of the liquid photopolymer, the cured photopolymer forming the first portion is pulled out of the vat 304 by the build plate 302, more liquid photopolymer is added to the vat 304 if needed and the build plate lowers the previously exposed and cured first portion of the part into the photopolymer to form a second portion of the part 308 with the light source being repositioned corresponding to the second portion of the part. Any number of exposure portions may be utilized to keep the pull force below the maximum allowable pull force for the part 308.

[0038] In various embodiments, some layers of a part may utilize multiple exposure portions of a layer, while other layers of a part may not require multiple exposure portions of a layer, wherethe part has varying areas for different layers. In various embodiments, where the area of the layer requires portioning of the exposure areas to keep the pull force below the maximum allowable pull force for the layer, one exposure area or a plurality of exposure areas may be exposed for each of a plurality of pulls of the build plate 302. For example, a layer may be formed with two exposure portions (also known as cure zones), with a first exposure portion being utilized for a first pull of the cured photopolymer corresponding to the first exposure portion and a second exposure portion being utilized for a second pull of the cured photopolymer corresponding to the second exposure portion. As another example, a layer may be formed with four exposure portions, with first and second exposure portions being utilized for a first pull of the cured photopolymer corresponding to the first and second exposure portions, and third and fourth exposure portions being utilized for a second pull of the cured photopolymer corresponding to the third and fourth exposure portions. Any number of exposure portions may be utilized to keep the pull force for each pull below the maximum allowable pull force. The exposure portions for the first pul may be adjacent to each other or may be separated from each other. One or a plurality of light sources may be used.

[0039] Figure 4 illustrates the positioning of a plurality of exposure portions (cure zones) 404 positioned relative to a vat 402. In this example, there are eight exposure portions 404, although any number of exposure portions may be used.

[0040] Figure 5 illustrates a part 502 being printed by a stereolithographic 3D printer according to various embodiments. The part 502 is printed by forming successive layers on the build plate 504. Layer 506 and layer 511 are two layers of part 502 that are printed. Layer 506 may have one exposure portion 512 for exposure by the light source. If the layer 506 has an area that would result in the pull force used to be above the maximum allowable pull force, then the layer 506 could be formed with a plurality of exposure portions to ensure that the pull force is below the maximum allowable pull force.

[0041] Layer 511 may have two separate layer portions 508 and 510 that may be formed with two exposure portions 514 and 516. The stereolithographic 3D printer may be configured to expose the exposure portions 514 and 516 separately by movement of the light source. If the stereolithographic 3D printer determines that pulling of both layer portions 508 and 510 of the layer will result in a pull force being used above a maximum allowable pull force, the printer will form the layer portions 508 and 510 with different liquid photopolymer and separately pulling ofthe layer portions 508 and 510 out of the vat to keep the pull force below the maximum allowable pull force.

[0042] Figure 6 illustrates a part 604 being printed by a stereolithographic 3D printer according to various embodiments. The part 604 is printed by forming successive layers on the build plate 602. Layer 606 and layer 608 are two layers of part 604 that are printed and are shown separated by other layers, each layer being separately printed. Layer 606 may be a first layer attached to the build plate 602. Layer 606 may be formed with eight exposure portions 610, where the light source is successively positioned below each exposure portion 610 to cure the liquid photopolymer to form each portion. The printer may determine that the pull force for forming the entire layer 606 with one pull may be below a maximum allowable pull force, in which case the entire layer 606 may be formed with one pull of the build plate 602. In this case, the printer may be configured to cause the light source to expose all of the exposure portions 610 corresponding to the layer to be exposed at a same time, and only one pull will be required to form the layer 606.

[0043] If the printer determines that pulling the entire layer 606 from the vat after exposing the photopolymer for the entire layer 606 will result in a pull force above a maximum allowable pull force, the printer will divide the layer into a plurality of exposure portions and do a plurality of pulls of the cured photopolymer of the layer to reduce the pull force for each pull to be below the maximum allowable pull force. The printer can use any number of exposure areas and any number of pulls of a portion of the layer to reduce the pull force for each portion being formed with a pull to be below the maximum allowable pull force as needed. In some embodiments where one pull for an entire layer will result in a pull force above a maximum allowable pull force, the printer may determine a minimum number of exposures required to form the entire layer while keeping the pull force for each pull below the maximum allowable pull force.

[0044] Layer 608 of part 604 has a smaller area than layer 606 and thus may be formed with a smaller number of exposure portions 612 while keeping the pull force below a maximum allowable pull force. In the example of Figure 6, six exposure portions 612 are shown. The layer 608 may be formed with one pull of the build plate 602 by exposing all of the exposure portions for layer 606 at one time and pulling the entire layer 606 if the pull force is below the maximum allowable pull force, or by using a plurality of exposures of the exposure portions 612 successively with a plurality of pulls as needed to reduce the pull force for each pull to be below the maximum allowable pull force.

[0045] Figure 7 illustrates sixteen exposure portions, with exposure portions 702 and 704 numerated. Figure 7 also illustrates how the light source can move in horizontal or vertical directions and at an angled direction as shown by the directional arrows. While the exposure portions in Figure 7 are illustrated as being spaced apart, the exposure areas may be overlapped or spaced as needed.

[0046] Figure 8 illustrates five exposure portions, with exposure portions 802 and 804 numerated. Figure 8 also illustrates how the light source can move in a radial direction to expose the exposure portions 802 and 804.

[0047] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and / or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). In those instanceswhere a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and / or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.” In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

Claims

CLAIMSWhat is claimed is:

1. A method of printing a part with a stereolithographic three-dimensional printer by successively forming layers of the part on a build plate, comprising: inserting liquid photopolymer into a vat; successively forming layers of the part on a build plate by lowering the build plate into the liquid photopolymer, curing each layer with a movable light source to cure the layer, and pulling the build plate with the cured layer out of the vat using a pull force; wherein forming each of the layers of the part comprises: determining a pull force needed for the build plate to pull each respective layer of the part out of the vat after curing of the liquid photopolymer by the light source; comparing the pull force needed for the build plate to pull each respective layer of the part out of the vat to a predetermined pull force; if the pull force needed to pull the build plate with the cured layer of the part out of the vat is above the predetermined pull force, forming the respective layer of the pail by forming a first portion of the respective layer on the build plate by curing the first portion of the respective layer with the light source, and pulling the build plate with the first portion of the respective layer out of the vat using a pull force below the predetermined pull force, and forming a second portion of the respective layer by inserting the build plate with the first portion of the respective layer into the vat, forming the second portion of the respective layer on the build plate adjacent to the first portion of the respective layer by curing the second portion of the respective layer with the light source and pulling the build plate with the cured first portion of the respective layer and with the cured second portion of the respective layer out of the vat using a pull force below the predetermined pull force; andwherein the pull force used to pull the respective layer out of the vat is below the predetermined pull force to prevent damage to the part.

2. The method of claim 1, further comprising, when the pull force is determined to be above the predetermined pull force for a respective layer of the part, determining a number of portions to divide the respective layer of the pail into to keep the pull force needed to pull the build plate out of the vat with each of the portions below the predetermined pull force.

3. The method of claim 1, further comprising moving the light source to cure the portions of the respective layer when a plurality of portions are cured for the layer to keep the pull force below the predetermined pull force.

4. The method of claim 1, further comprising receiving an entry of the predetermined pull force from a user.

5. The method of claim 1, further comprising determining the predetermined pull force based on a type of the liquid photopolymer.

6. The method of claim 1, wherein the controller is configured to determine the predetermined pull force based on a surface area of the layer of the part.

7. The method of claim 1, further comprising forming the respective layer of the part by forming a first portion and a third portion of the respective layer on the build plate by curing the first portion and the third portion of the respective layer with the light source, and pulling the build plate with the first portion and the third portion of the respective layer out of the vat using a pull force below the predetermined pull force, and forming a second portion and a fourth portion of the respective layer by inserting the build plate with the first portion and the third portion of the respective layer into the vat, forming the second portion and the fourth portion of the respective layer on the build plate adjacent to the first portion and the third portion of the respective layer by curing thesecond portion and the fourth portion of the respective layer with the light source, and pulling the build plate with the cured first, second, third and fourth portions of the respective layer out of the vat using a pull force below the predetermined pull force.

8. A stereolithographic three-dimensional printer configured to print a part, comprising; a vat for holding liquid photopolymer; a build plate; a light source; and a controller configured to successively form layers of the part on the build plate by lowering the build plate into the liquid photopolymer, curing each layer with the light source, and pulling the build plate with the corresponding cured layer out of the vat using a pull force, wherein the controller is configured to successively form each of the layers of the part by: determining a pull force needed for the build plate to pull each respective layer of the part out of the vat after curing of the liquid photopolymer by the light source; comparing the pull force needed for the build plate to pull each respective layer of the part out of the vat to a predetermined pull force; if the pull force needed to pull the build plate with the cured layer of the part out of the vat is above the predetermined pull force, forming the respective layer of the part by forming a first portion of the respective layer on the build plate by curing the first portion of the respective layer with the light source, and pulling the build plate with first portion of the respective layer out of the vat using a pull force below the predetermined pull force, and forming a second portion of the respective layer by inserting the build plate with the first portion of the respective layer into the vat, forming the second portion of the respective layer on the build plate adjacent to the first portion of the respective layer by curing the second portion of the respective layer with the light source and pulling the build plate with the cured first portion and the cured second portion of the respective layer out of the vat using a pull force below the predetermined pull force; andwherein the pull force used to pull the respective layer out of the vat is below the predetermined pull force to prevent damage to the part.

9. The printer of claim 8, wherein when the pull force is determined to be above the predetermined pull force for a respective layer of the part, the controller determines a number of portions to divide the respective layer of the pail into to keep the pull force needed to pull the build plate out of the vat with each of the portions below the predetermined pull force.

10. The printer of claim 8, wherein the controller is configured to move the light source to cure the portions of the respective layer when a plurality of portions are cured for the layer to keep the pull force below the predetermined pull force.

11. The printer of claim 8, further comprising a user interface configured for receiving an entry of the predetermined pull force from a user.

12. The printer of claim 8, wherein the controller is configured to determine the predetermined pull force based on a type of the liquid photopolymer.

13. The printer of claim 8, wherein the controller is configured to determine the predetermined pull force based on a surface area of the layer of the part.

14. The printer of claim 8, wherein the controller is configured to form the respective layer of the part by forming a first portion and a third portion of the respective layer on the build plate by curing the first portion and the third portion of the respective layer with the light source, and pulling the build plate with the first portion and the third portion of the respective layer out of the vat using a pull force below the predetermined pull force, and forming a second portion and a fourth portion of the respective layer by inserting the build plate with the first portion and the third portion of the respective layer into the vat, forming the second portion and the fourth portion of the respective layer on the build plate adjacent to the first portion and the third portion of therespective layer by curing the second portion and the fourth portion of the respective layer with the light source, and pulling the build plate with the cured first, second, third and fourth portions of the respective layer out of the vat using a pull force below the predetermined pull force.

15. A stereolithographic three-dimensional printer configured to print a part, comprising: a vat for holding liquid photopolymer; a build plate; a light source; and a controller configured to successively form layers of the part on the build plate by lowering the build plate into the liquid photopolymer, curing each layer with the light source, and pulling the build plate with the corresponding cured layer out of the vat using a pull force, wherein the controller is configured to successively form each of the layers of the part by: determining whether a pull force needed for the build plate to pull each respective layer of the part out of the vat after curing of the liquid photopolymer by the light source is above a predetermined pull force; forming the respective layer of the part as a single portion if the determined pull force is below the predetermined pull force; and forming the respective layer of the part as a plurality of portions if the determined pull force is above the predetermined pull force, wherein the pull force used to pull the respective layer out of the vat is below the predetermined pull force to prevent damage to the part.

16. The printer of claim 15, wherein when the pull force is determined to be above the predetermined pull force for a respective layer of the pail, the controller determines a number of portions to divide the respective layer of the part into to keep the pull force needed to pull the build plate out of the vat with each of the portions below the predetermined pull force.

17. The printer of claim 15, wherein the controller is configured to move the light source to cure the portions of the respective layer when a plurality of portions arc cured for the layer to keep the pull force below the predetermined pull force.

18. The printer of claim 15, further comprising a user interface configured for receiving an entry of the predetermined pull force from a user.

19. The printer of claim 15, wherein the controller is configured to determine the predetermined pull force based on a type of the liquid photopolymer.

20. The printer of claim 15, wherein the controller is configured to determine the predetermined pull force based on a surface area of the layer of the part.

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