Abstract:
An external table height adjustment technique for a printer system is disclosed. An operator can align an image gap between a printer table of the printer system and a printhead carriage via a height adjustment mechanism. The operator can perform the table height adjustment while a belt is installed on the printer table and media is loaded on top of the printer table. A height adjustment assembly is secured onto a supporting frame of the printer table such that an adjustment component exposed beyond an edge of the belt can raise or lower a portion of the printer table where the height adjustment assembly is secured.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent Ser. No. 14/178,236, filed Feb. 11, 2014, which is incorporated in its entirety by this reference hereto. 
     
    
     RELATED FIELD 
       [0002]    This disclosure relates generally to printer alignment systems and in particular to a technique of printer table height adjustment. 
       BACKGROUND 
       [0003]    A printer system may require precise alignment of a printer table or roller relative to the printheads. The precise alignment ensures a constant height between the printer table and the printhead nozzles such that inkjet dots have a consistent shape and are accurately placed. Conventionally, setting an image plane on hybrid tables with belts requires the belt to be removed. An operator can measure the table height and make best guess adjustments after the belt is removed. Thereafter, the belt is reassembled and the entire system is revalidated. This conventional process is time-consuming and inaccurate, causing a large variation in terms of alignment. 
       SUMMARY 
       [0004]    Disclosed is a technique for precision alignment of printer table/rollers to the printheads utilizing an external table height adjustment mechanism. Such precise alignment may be part of the manufacturing and quality control process of building printer systems. Such precise alignment may also be part of a printer system maintenance process. Particularly, the disclosed mechanism facilitates precise control of the image plane gap, thus considerably improving upon dot placement accuracy, which impacts everything from color variation, to gloss, and to overall image quality of the printed results. 
         [0005]    The disclosed technique includes adjustment of the image plane via the height adjustment mechanism after the belt has been installed and while media is positioned on the printer table with vacuum pull. The height adjustment mechanism allows for the height from the image plane to the printhead nozzles to be precisely adjusted. Being able to externally adjust the image plane gap with the belt installed greatly improves dot placement while decreasing the costly trial and error adjustment process with the removal of the belt. The external table height adjustments account for imperfections in tables and rollers of printer systems, as well as the imperfections in the bar that holds the printhead carriage. The disclosed technique cures these imperfections quickly during the quality control process of manufacturing or during maintenance operations. 
         [0006]    The disclosed height adjustment mechanism may include multiple adjustment assemblies located across and underneath the printer table. Each adjustment assembly may be controlled via an adjustment nut on or in contact with (directly or indirectly) a side plate of the printer table frame. For example, the adjustment assembly may include a long rod through the adjustment nut such that the rotation of the adjustment nut can change the height of the adjustment assembly. The adjustment assemblies may be used to adjust the printer table to conform the image gap from the printhead nozzle locations to any point over the image plane. This process reduces production time of these printer systems, enables the ability to precisely place dots, and increases the printing consistency of the printer systems. 
         [0007]    Some embodiments of this disclosure have other aspects, elements, features, and steps in addition to or in place of what is described above. These potential additions and replacements are described throughout the rest of the specification. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of a portion of a printer system with a vacuum table. 
           [0009]      FIG. 2A  is a perspective view of a printhead carriage. 
           [0010]      FIG. 2B  is a perspective plan view of where printhead nozzles of the printhead carriage of  FIG. 2A  are located. 
           [0011]      FIG. 3  is a flow chart of a process of measuring table height of a printer system. 
           [0012]      FIG. 4A  is a perspective plan view of a printer table with external height adjustment mechanisms. 
           [0013]      FIG. 4B  is a spatial map illustrating a top plan view of the printer table of  FIG. 4A  and exemplary locations of the external height adjustment mechanisms. 
           [0014]      FIG. 5  is a flow chart of a process of adjusting the table height of a printer system after a belt is installed on the table. 
           [0015]      FIG. 6  is a diagram illustrating the adjustment sequence as applied to the printer table of  FIG. 4   
           [0016]      FIG. 7A  is a first detailed perspective view of the printer table of  FIG. 4A . 
           [0017]      FIG. 7B  is a second detailed perspective view of the printer table of  FIG. 4A . 
           [0018]      FIG. 7C  is a third detailed perspective view of the printer table of  FIG. 4A . 
           [0019]      FIG. 8A  is a components diagram illustrating a partial assembly of a height adjustment mechanism. 
           [0020]      FIG. 8B  is a perspective view illustrating the height adjustment mechanism of  FIG. 8A  after assembly and before attaching the height adjustment mechanism to a printer table. 
           [0021]      FIG. 8C  is a perspective view illustrating the height adjustment mechanism of  FIG. 8B  after attaching the height adjustment mechanism to a side plate of the printer table. 
           [0022]      FIG. 9A  is a side view of a first example of a height adjustment mechanism without illustrating the rod that extends to connect with the adjustment nut. 
           [0023]      FIG. 9B  is a side view of a second example of a height adjustment mechanism without illustrating the rod that extends to connect with the adjustment nut. 
       
    
    
       [0024]    The figures depict various embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the invention described herein. 
       DETAILED DESCRIPTION 
       [0025]      FIG. 1  is a perspective view of a portion of a printer system  100  with a printer table  104 . The printer system  100  can be a grand format printer, a wide format printer, a screen printer, or any other type of inkjet printer. The printer table  104  is a structure with a substantially flat surface for carrying a substrate or media. The printer table  104  may be coupled to a vacuum blower to create a vacuum pull to secure the substrate or media on the printer table  104 . A belt  106  may be installed on the printer table  104 . The belt  106  can be an endless belt. The belt  106  can convey the substrate or media towards or away from a carriage  108 . The carriage  108  is a movable component of the printer system  100 . The carriage  108  contains the printheads of the printer system  100 . The carriage  108  can scan across over the substrate or media in directions substantially perpendicular to the movement direction of the belt  106 . For example, the carriage  108  can glide along a carriage bar (not shown) over the printer table  104 . 
         [0026]      FIG. 1  also illustrates adjustment locations  110  over the printer table  104  along the width of the belt  106 . The adjustment locations  110  are positions on the printer table  104  where height distances between the printer table  104  and the carriage  108  are measured for the purpose of table alignment. 
         [0027]    For the purpose of this disclosure, a direction of travel for a top surface of the belt  106  facing the carriage  108  may be referred to as “backward” and an opposite direction from that may be referred to as “forward.” The direction towards one end of the belt  106  (e.g., away from the illustrated position of the carriage  108 ) may be referred to as the “left” side, and the direction towards the other end of the belt  106  e.g., at the illustrated position of the carriage  108 ) may be referred to as the “right” side. It is noted, however, the terms “forward,” “backward,” “left,” and “right” are used to distinguish one end of a structure from another without necessarily requiring or implying a direction from an operator&#39;s perspective. 
         [0028]      FIG. 2A  is a perspective view of a printhead carriage  202 . The printhead carriage  202  may be the carriage  108  of  FIG. 1 . The printhead carriage  202  includes or is attached to dial indicators  208 . The dial indicators  208  are instruments used to accurately measure small distances and/or angles. The printhead carriage  202  can include exactly four or any other number of dial indicators. For example, the dial indicators  208  can be positioned towards four corners of the printhead carriage  202 . The dial indicators  208  may include a dial display, in which a needle points to graduations in a circular array around the dial display. The dial indicators  208  may electronically output the measurements to an alignment system (not shown) acting as an operator of the printer system for the purpose of table alignment. The operator of a printer system, such as the printer system  100  of  FIG. 1 , can use the dial indicators  208  to measure the gap distance from the printhead nozzles  210  to a printer table, such as the printer table  104  of  FIG. 1 . 
         [0029]      FIG. 2B  is a perspective plan view of where printhead nozzles  210  of the printhead carriage  202  of  FIG. 2A  are located. The printhead nozzles  210  can correspond respectively to different colors of inkjets, such as magenta, yellow, cyan, and black. This disclosure also contemplates any other combination of printheads and/or inkjet colors. The dial indicators  208  can be aligned with the positions of the printhead nozzles  210 , such as at the corners of the printhead nozzles  210 , for the purpose of table height measurement. 
         [0030]      FIG. 3  is a flow chart of a process  300  of measuring table height of a printer system, such as the printer system  100  of  FIG. 1 . The table height to be measured may be a distance from the top flat surface of a printer table (e.g., the printer table  104  of  FIG. 1 ) to printhead nozzles (e.g., the printhead nozzles  210  of  FIG. 2 ) of the printer system. The process  300  begins with placing a piece of media onto the printer table in step  302 . In response to a command, the printer system can produce a vacuum pull over the printer table to hold the media in place in step  304 . 
         [0031]    An operator can move a printhead carriage, such as the printhead carriage  202  of  FIG. 2 , over the target print area on the printer table in step  306 . The “operator” referenced in this disclosure refers to a person, an electronic and/or mechanical alignment system, the printer system, or a combination thereof. The printhead carriage includes or is attached to dial indicators, such as the dial indicators  208  of  FIG. 2 . The dial indicators can be set at positions of the printhead nozzles in step  308 . For example, the positions can include the positions of the printhead nozzles illustrated in  FIG. 2 . The operator can then ensure a constant gap at the indicator positions in step  310 . For example, the constant gap can be exactly or substantially near 0.060 inches. 
         [0032]    The operator then zeroes all of the dial indicators, in step  312 , and proceeds to move the printhead carriage to the far right of the printer table in step  314 . The operator marks the positions of the adjustment locations, such as the adjustment locations  110  of  FIG. 1 , in step  316 . For example, the positions can be marked and recorded as distances along and from (e.g., on a Cartesian coordinate) the left edge of a belt on the printer table, such as the belt  106  of  FIG. 1 . The printhead carriage can then be moved, in step  318 , from right to left, stopping whenever at least some of the dial indicators aligned over the centerlines of the adjustment locations. In some embodiments, the movement may include forward and backward as well. Whenever at least two of the dial indicators are aligned over the centerlines of the adjustment points, the operator can record, in step  320 , the distance measurements made by the dial indicators. In alternative embodiments, a pinpoint laser measurement or alignment tool can be used instead or in combination with the dial indicators to measure the distances. 
         [0033]    Step  318  and step  320  may be repeated until distance measurements are recorded for all adjustment points. For example, there can be a total of 8 measurements in the illustrated example (e.g., two measurements, front and back of the carriage, for each pair of the adjustment locations). The printhead carriage is left at the far left position when all measurements are completed. 
         [0034]      FIG. 4A  is a perspective plan view of a printer table  400  with external height adjustment mechanisms  402 . Detailed views of the printer table  400  are further illustrated in  FIGS. 7A-7C . The printer table  400  includes a supporting structure  404 , such as a metallic frame. For example, the supporting structure  404  may include four lengthwise bars  406  and several linkage bars  408  therebetween. Structural linkages can hold the supporting structure  404  together with two side plates  410  opposite to one another. The side plates  410  attach the printer table  400  to the rest of a printer system. The printer table  400  may include a shell  412 . The shell  412  can cover at least a top portion of the printer table  400 . The shell can also interface with a belt, such as the belt  106  of  FIG. 1 , which can be installed on the printer table  400  to convey a substrate or media. 
         [0035]    The external height adjustment mechanisms  402  are distributed in multiple locations on the supporting structure  404 . Each external height adjustment mechanism includes at least a height adjustment assembly  414  and an adjustment nut  418 . The height adjustment assembly  414  is attached to the printer table  400  to raise or lower a portion of the printer table  400 . For example, the height adjustment assembly  414  can push or pull against the shell  412  covering the printer table  400 . The adjustment nut  418  is coupled to the height adjustment assembly  414  such that turning the adjustment nut  418  controls the lowering or raising of the printer table  400 . In various embodiments, the adjustment nut  418  is turned in conjunction with a bolt nut (not shown) on the other side of the side plates  410 . This is further illustrated in  FIG. 8B . 
         [0036]    An operator aligning the printer table  400  can externally adjust each of the external height adjustment mechanisms  402  via the adjustment nut  418  corresponding to a specific adjustment location on the printer table  400 . The specific adjustment locations indicate where instances of the height adjustment assembly  414  are installed. For example, the adjustment locations can be the adjustment locations  110  of  FIG. 1 . 
         [0037]      FIG. 4B  is a spatial map illustrating a top plan view of the printer table  400  of  FIG. 4A  and exemplary locations  420  of the external height adjustment mechanisms  402 .  FIG. 4B  illustrates twelve adjustment locations  420  spread out through the printer table  400 . Along each of the side plates  410 , the locations labeled with the letter “A” correspond to a top set of adjustment nuts  422 A. The top set of adjustment nuts  422 A can correspond to outboard adjustment locations  420 A. The outboard adjustment locations  420 A are the adjustment locations  420  that are closest to the edge of the printer table  400 . 
         [0038]    Along each of the side plates  410 , the locations labeled with the letter “B” correspond to a bottom set of adjustment nuts  422 B. The bottom set of adjustment nuts  422 B can correspond to inboard adjustment locations  420 B. The inboard adjustment locations  420 B are the adjustment locations  420  that are closest to the center of the printer table  400 . 
         [0039]      FIG. 5  is a flow chart of a process  500  of adjusting the table height of a printer system after a belt is installed on a printer table of the printer system. The printer table can be the printer table  104  of  FIG. 1  or the printer table  400  of  FIG. 4 . The process  500  may depend on the table height measurements taken via performing the process  300  of  FIG. 3 . The process  500  begins with inputting the distance measurements from process  300  into an adjustment configuration system in step  502 . The adjustment configuration system can be a computing device, such as a laptop, a desktop computer, or a computing server. Upon receiving the distance measurements, the adjustment configuration system computes and displays, in step  504 , the required adjustments for the printer table at each adjustment location, such as the adjustment locations  110  of  FIG. 1  or the adjustment locations  420  of  FIG. 4B . 
         [0040]    In response step  504 , an operator of the printer table can tune adjustment mechanisms, such as the height adjustment mechanisms  402  of  FIG. 4A , in the printer table, in step  506 , to match the required adjustments. For example, the height adjustment mechanisms can include adjustment nuts, such as the adjustment nut  418  of  FIG. 4A , respectively controlling height adjustment assemblies at the adjustment locations. The adjustment nuts are located alongside side plates of a supporting frame (e.g., the supporting structure  404  of  FIG. 4A ) of the printer table. As part of the adjustment step  506 , the operator can turn the adjustment nuts in accordance with the required adjustments and an adjustment ratio. For example, the adjustment ratio may dictate that a 90° turn of each adjustment nut corresponds to 0.005″ of height adjustment. 
         [0041]    In at least some embodiments, the adjustments are made on the printer table in a single direction (e.g., from right to left or left to right) such that the printer table is stretched in one direction only. For example,  FIG. 6  is a diagram illustrating the adjustment sequence as applied to the printer table  400  of  FIG. 4A . In the beginning of step  506 , the operator performs a first set of adjustments  602  on the right most adjustment locations. Then the operator moves on to a second set of adjustments  604 , a third set of adjustments  606 , and a fourth set of adjustments  608  until all of the required adjustments are completed. 
         [0042]    The operator verifies the adjustments in step  508  by taking the distance measurements at each of the adjustment locations in a similar fashion as the process  300  of  FIG. 3 . In some embodiments, the operator verifies the adjustments in a direction opposite to the direction of the distance measurements. For example, if the distance measurements are taken with the carriage moving from the right side of the printer table to the left side, then the verification measurements can be taken with the carriage moving from the left side of the printer table to the right side. 
         [0043]    The operator of the described processes can be a person, an automated electronic/mechanical machine, an electronic component of the printer system, or a combination thereof. The operator may describe a person operating an alignment system, where a processor, a controller, or other electronic circuitry can implement the alignment system. The processes described can be manual, semi-automatic, or automated. For example, the processes can be implemented as a set of instructions, stored on a memory, which can be executed by a processor. The processes described involving the printer table may equally apply to printer rollers as well. The processes described involving the dial indicators may equally apply where the dial indicators are replaced by other distance measuring devices, such as pinpoint laser measurement devices. 
         [0044]    While steps or blocks are presented in  FIGS. 3 and 5  in a given order, alternative embodiments may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified to provide alternative or subcombinations. Each of these processes or blocks may be implemented in a variety of different ways. Also, while processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed in parallel, or may be performed at different times. Further, any specific numbers noted herein are only examples: alternative implementations may employ differing values or ranges. 
         [0045]      FIG. 7A  is a first detailed perspective view of the printer table  400  of  FIG. 4A . Specifically,  FIG. 7A  is a detailed diagram of the area labeled “A” circled in  FIG. 4A . Illustrated are at least four height adjustment mechanisms  402  labeled  402 A,  404 B,  402 C, and  402 D respectively. As shown, an instance of the adjustment nut  418  is mounted through one of the side plates  410 . The adjustment nut  418  controls lateral movement of the rod  422 . The rod  422  is a part of the height adjustment assembly  414 . The rod  422  can run parallel to one of the lengthwise bars  406 . 
         [0046]      FIG. 7B  is a second detailed perspective view of the printer table  400  of  FIG. 4A . Specifically,  FIG. 7B  is a detailed diagram of the area labeled “B” circled in  FIG. 4A . As shown, the rod  422  terminates on a linkage structure  426 . The linkage structure  426  is a part of the height adjustment assembly  414 . The linkage structure  426  couples to a table interface  428  and a frame interface  430  of the height adjustment assembly  414 . The linkage structure  426  can be attached via shoulder screws on both ends, one to the table interface  428  and one to the frame interface  430 . 
         [0047]    The table interface  428  is a structure that attaches to a top portion of the printer table  400 , such as the shell  412 . The table interface  428  includes a mounting bracket  432  and a thermal expansion compensation pin  434 . The mounting bracket  432  can be attached to the shell  412 . The thermal expansion compensation pin  434  can run through two ends of the mounting bracket  432 . The linkage structure  426  can be attached to the thermal expansion compensation pin  434 . The frame interface  430  is a mounting block that attaches to one of the lengthwise bars  406  of the supporting structure  404 . The described components can be attached to each other in a variety of ways, including mechanical attachments (e.g., shoulder screws) and adhesive attachments (e.g., glue). The linkage structure  426  can be attached using a screw or hinge that enables the attached linkage structure  426  to rotate/pivot at the points of attachment to either the thermal expansion compensation pin  434  or the frame interface  430 . 
         [0048]    The adjustment nut  418  can be adapted such that turning the adjustment nut  418  clockwise would pull the rod  422  towards the adjustment nut  418  and turning the adjustment nut counter-clockwise would push the rod  422  away from the adjustment nut  418 . In various embodiments, the adjustment nut  418  is turned in conjunction with a bolt nut (not shown) around the rod  422  on the opposite side of the side plate  410 . In the illustrated configuration, when the rod  422  is pulled, the linkage structure  426  straightens and raises the table interface  428 . When the rod  422  is pushed, the linkage structure  426  slants and lowers the table interface  428 . 
         [0049]      FIG. 7C  is a third detailed perspective view of the printer table  400  of  FIG. 4A . Specifically,  FIG. 7C  is a detailed diagram of the area labeled “C” circled in  FIG. 7A .  FIG. 7C  illustrates the rod  422  that extends from the adjustment nut  418  (not shown this figure) towards one instance of the height adjustment assembly  414  (not shown in this figure). The rod  422  can be held in place by a corner bracket  440 . The corner bracket  440  is attached to one of the lengthwise bars  406 . The corner bracket  440  may serve as a rod guide to mitigate the bending of the rod  422 , especially for instances of the rod  422 , which extends farther towards the inner/central portion of the printer table  400 . The rod  422  traverses through a hole in the corner bracket  440 . The corner bracket  440  holds the rod  422  in place vertically while allowing the rod  422  to extend or retract based on rotation of the adjustment nut  418 . 
         [0050]      FIG. 8A  is a components diagram illustrating a partial assembly of a height adjustment mechanism  800  for a printer table. The printer table can be the printer table  400  of  FIG. 4A . The height adjustment mechanism  800  can be one of the external height adjustment mechanisms  402  of  FIG. 4A . The height adjustment mechanism  800  includes a frame interface  802 , a table interface  804 , a linkage  806 , a rod interface  808 , a first shoulder screw  810 , and a second shoulder screw  812 . The table interface  804  may include a mounting bracket  814  and a compensation pin  816 . The components of the height adjustment mechanism  800  may be consistent with the components of the height adjustment mechanisms  402  of  FIG. 4A . 
         [0051]    The mounting bracket  814  can be a rigid structure with two arms extending from both ends of a center portion. Each arm can form a right angle with the center portion. Each arm includes a hole. The compensation pin  816  passes through both of the holes. The compensation pin  816  includes an off-center tapped hole adapted to fit the first shoulder screw  810 . The tapped hole may be surrounded by a flattened groove in the compensation pin  816 . The center portion may include one or more holes, such as tapped holes, so that screws, pins, or nails can traverse through the one or more holes to attach the mounting bracket  814  to a shell of the printer table, such as the shell  412  of the printer table  400 . 
         [0052]    The linkage  806 , the rod interface  808 , and the compensation pin  816  can be held together by inserting the first shoulder screw  810  through a first hole in the rod interface  808  and a first hole in the linkage  806 , and screwing the first shoulder screw  810  into the tapped hole of the compensation pin  816 . The rod interface  808  may be an L-shape block having two sides perpendicular to each other. The rod interface  808  includes a first hole through the first side and a second hole through the second side. The second hole of the rod interface  808  may be used to attach a rod (not shown in this figure) controlled by an adjustment nut (not shown in this figure). The linkage  806  may be a rectangular bar having the first hole near one end of the bar and a second hole near the other end of the bar. The first shoulder screw  810  may be adapted with a screw length longer than a depth of the off-center tapped hole of the compensation pin  816  and a combined thickness of the linkage  806  and the rod interface  808  of which the first shoulder screw  810  penetrates. Under thermal expansion of the mounting bracket  814 , the compensation pin  816  can provide lateral compensation (e.g., along its length) for the expansion and the lengthened first shoulder screw  810  can provide longitudinal compensation for the expansion. 
         [0053]    The linkage  806  and the frame interface  802  can be held together by inserting the second shoulder screw  812  through the second hole of the linkage  806  and screwing the second shoulder screw  812  into a first hole of the frame interface  802 . The frame interface  802  may be a mounting block having the first hole fitted for the second shoulder screw  812 . The first hole of the frame interface  802  may be a tapped hole. The mounting block may have several other holes such that screws, pins, or nails can attach the mounting block onto the frame of the printer table, such as the supporting structure  404  of the printer table  400 . 
         [0054]      FIG. 8B  is a perspective view illustrating the height adjustment mechanism  800  of  FIG. 8A  after assembly and before attaching the height adjustment mechanism  800  to a printer table. The height adjustment mechanism  800  further includes a rod  820 . The rod  820  may be a bolt that is fastened by a nut onto the rod interface  808  through the second hole of the rod interface  808 . The second hole of the rod interface  808  may also be a tapped hole of which the rod  820  can be screwed into. 
         [0055]    On the other end of the rod  820  may be an adjustment nut  824  and a bolt nut  828 . The adjustment nut  824  may be the adjustment nut  418  of  FIG. 4A . The adjustment nut  824  and the bolt nut  828  can sandwich a side plate of the printer table frame, such as one of the side plates  410  of  FIG. 4A . The bolt nut  828  can be a capped nut, a locknut, a flanged nut, etc. The adjustment nut  824  is configured to be able to move the rod  820  towards or away from the frame interface  802  by rotating around the rod  820 . In various embodiments, the adjustment nut  824  is turned in conjunction with the bolt nut  828  around the rod  820  on the opposite side of the side plate in order to extend or retract the rod  820  towards or away from the mounting bracket  814 . Washers  832 , such as flat washers, beveled washers, contact washers, lock washers, or spring washers, may be inserted between the adjustment nut  824  and the side plate, and between bolt nut  828  and the side plate. Use of the beveled washers can compensate bending of the rod  820  near the side plate. On the other hand, bending of the rod  820  that extends away from the side plate can be mitigated by positioning the linkage  806  on the outward side. This enables the linkage  806  to leverage the printer table weight and belt tension that provides a downward force which puts the rod  820  in tension. 
         [0056]    The complete assembly of the height adjustment mechanism  800  may also include bolt assemblies  834 , including one or more bolts, nuts, and washers, for attaching the height adjustment mechanism  800  to the frame of the printer table, such as the supporting structure  404  of  FIG. 4A . For example, the bolt assemblies  834  may be inserted through the holes within the frame interface  802  and fastened with a bolt nut. 
         [0057]      FIG. 8C  is a perspective view illustrating the height adjustment mechanism  800  of  FIG. 8B  after attaching the height adjustment mechanism  800  to a side plate  840  of the printer table. The side plate  840  may be one of the side plates  410  of  FIG. 4A . As shown, the rod  820  is inserted through a hole in the side plate  840  with the adjustment nut  824  facing inward towards the complete assembly of the height adjustment mechanism  800 . 
         [0058]      FIG. 9A  is a side view of a first example of a height adjustment mechanism  900 A without illustrating the rod that extends to connect with the adjustment nut. The height adjustment mechanism  900 A may be one of the external height adjustment mechanisms  402  of  FIG. 4A . The height adjustment mechanism  900 A may be the height adjustment mechanism  800  of  FIG. 8A . This first example is configured for the left side of the printer table.  FIG. 9B  is a side view of a second example of a height adjustment mechanism  900 B without illustrating the rod that extends to connect with the adjustment nut. This second example is configured for the right side of the printer table. 
         [0059]    Reference in this specification to “various embodiments” or “some embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Alternative embodiments (e.g., referenced as “other embodiments”) are not mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described, which may be requirements for some embodiments but not other embodiments.