TECHNICAL FIELD AND BACKGROUND

The present disclosure relates to a machine support frame for supporting a machine, in particular a vibration sensitive machine; and methods of installation.

Vibration sensitive machines, e.g. lithography machines, electron microscopes, and semiconductor production equipment, may benefit from a machine support frame (MSF) having as little resonances as possible. To suppress resonances, at least for typical environmental vibration, the frame preferably has a high stiffness. Furthermore, the MSF typically includes a massive support plate which should resist deformation. Preferably, the frame should typically be able to withstand forces of a few hundred kilo Newton (e.g. including the machine, possible with seismic shock) while avoiding resonances below hundred Hertz.

These and other requirements make it difficult to provide any adjustability to the frame. Accordingly, an MSF design is typically pre fabricated according to specific dimensions depending on a specific application. For example, the height of the MSF may depend on the height of the building floor or height of other surrounding equipment. For example, the width and length may depend on the size of the support plate or machine to be supported. Since the design may considerably vary for each case, it is difficult to keep the parts in supply. This may lead to long waiting times or high expenses in storage of many different parts.

Therefore, there remains a need for an improved MSF and method of installation. In particular, there is a need for a MSF having the necessary stiffness and the capacity to carry heavy loads, while being easy to install from stock components with adjustable height, e.g. between 250- 1300mm, preferably allowing to customize for different sizes of the support block. SUMMARY

Aspects of the present disclosure relate to a modular machine support frame for supporting a vibration sensitive machine, and method of assembling such frame. The frame can be conceptually divided in a top part, a bottom part, and an intermediate there between. The top part of the frame comprises a horizontally extending support plate. Typically, the support plate comprises mounting structures for mounting the vibration sensitive machine.

As described herein, the top part also comprises a set of horizontally elongate top bars connected to a bottom of the support plate. The bottom part similarly comprises a set of horizontally elongate bottom bars configured to support the frame on a floor. The intermediate part comprises a set of vertically extending side plates connected between the top and bottom parts. The side plates are fixed by bolting to respective vertical sections formed by downward and upward extending parts of the horizontally elongate top and bottom bars, respectively. The top part of the frame is carried by the side plates at an adjustable height from the floor.

The vertical sections in at least one of the top and bottom bars comprise vertically extending elongate slots for the bolting of the side plates at a specific position along a length of the slots to determine the adjustable height.

Advantageously, the respective vertical sections of the top and bottom bars are sandwiched between respective sets of at least two of the side plates on either sides of the vertical slots held together by the bolting. By the bolting through the side plates sandwiching the vertical sections, respective friction connections are formed with at least two frictional surfaces on either side of the vertical sections between each side of the respective vertical section and side plate for the carrying of the top part of the frame while maintaining the specific position of the bolting along the slots. As will be appreciated each frictional surface of a respective plate contacting the vertical sections may contribute in withstanding shear forces to carry a part of the load at an adjustable height provided by the slots, while the set of multiple side plates can form a sort of box construction to increase stiffness. The inventors find that both a sufficient stiffness and friction for the purposes of the MSF can be obtained using a plurality of bolts distributed along the side plates with a density that is on the one hand high enough to develop desired friction and on the other hand not so high as to compromise the structural integrity (due the corresponding holes/slots).

In combination, the MSF can provide relatively high stiffness and capacity to carry heavy loads, while being easy to install from stock components with adjustable height.

BRIEF DESCRIPTION OF DRAWINGS

These and other features, aspects, and advantages of the apparatus, systems and methods of the present disclosure will become better understood from the following description, appended claims, and accompanying drawing wherein:

FIG 1A illustrates a perspective translucent view of a modular machine support frame supporting a vibration sensitive machine;

FIG IB illustrates a cross-sectional view of a part of the frame;

FIG 1C illustrates a zoomed in view of the part;

FIGs 2A-2D illustrate variations of bottom bars connected to respective side plates;

FIGs 3A-3D illustrate one method of assembling the frame;

FIGs 4A-4D illustrate another method of assembling the frame;

FIG 5 illustrate various heights obtainable by a limited set of different side plate heights connected at a variable height between respective top and bottom bars; FIGs 6A and 6B illustrate a load applied to a corner of the frame, and calculated shearing forces for different bolting positions along the frame. DESCRIPTION OF EMBODIMENTS

Terminology used for describing particular embodiments is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term "and/or" includes any and all combinations of one or more of the associated listed items. It will be understood that the terms "comprises" and/or "comprising" specify the presence of stated features but do not preclude the presence or addition of one or more other features. It will be further understood that when a particular step of a method is referred to as subsequent to another step, it can directly follow said other step or one or more intermediate steps may be carried out before carrying out the particular step, unless specified otherwise. Likewise it will be understood that when a connection between structures or components is described, this connection may be established directly or through intermediate structures or components unless specified otherwise.

The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. In the drawings, the absolute and relative sizes of systems, components, layers, and regions may be exaggerated for clarity. Embodiments may be described with reference to schematic and/or cross- section illustrations of possibly idealized embodiments and intermediate structures of the invention. In the description and drawings, like numbers refer to like elements throughout. Relative terms as well as derivatives thereof should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the system be constructed or operated in a particular orientation unless stated otherwise.

FIG 1A illustrates a perspective translucent view of a modular machine support frame 100 e.g. suitable for supporting a vibration sensitive machine 200. FIG IB illustrates a cross-sectional view of a part of the frame. FIG 1C illustrates a zoomed in view of the part.

In some embodiments, the frame 100 comprises a top part 10 comprising a horizontally extending support plate 12, e.g. in the XY plane as shown. Preferably, the support plate 12 is provided with mounting structures 12m on top of the support plate 12 for mounting the vibration sensitive machine 200. In other or further embodiments, the top part 10 comprises a set of horizontally elongate top bars 11 preferably connected or connectable to a bottom of the support plate 12.

In some embodiments, the frame 100 comprises a bottom part 30 with a set of horizontally elongate bottom bars 31 configured to support the frame 100 on a floor 300. Preferably, the bottom bars 31 are similar or the same as the top bars 11. By using the same bars for both the top and bottom, the number of stock parts can be reduced. In one embodiment, the set of top bars and/or the set of bottom bars is welded together to form a respective structure.

In some embodiments, the frame 100 comprises an intermediate part 20 with a set of vertically extending side plates 22, e.g. in the XZ plane, YZ plane or any other vertical plane transverse to the horizontal plane XY. Preferably, the side plates 22 are connected between the top and bottom parts 10,30. For example, the side plates 22 are fixed by bolting 25 to respective vertical sections llv,31v formed by downward and upward extending parts of the horizontally elongate top and bottom bars 11,31, respectively. For example, the vertical sections llv,31v extend in the— Z, or +Z direction as shown. Optionally, some of the side plates can be welded together to form a respective structure.

In a preferred embodiment, the top part 10 of the frame 100 is carried C by the side plates 22 at an adjustable height H from the floor 300. More preferably the vertical sections llv,31v in at least one of the top and bottom bars 11,31 comprise vertically extending elongate slots 11s, 31s. Most preferably, e.g. as shown, the vertical slots are arranged side by side along a respective length of the top and/or bottom bars 11,31. As will be appreciated, the plurality of slots can be used in combination with a plurality of bolts for the bolting 25 of the side plates 22 at a specific position DH along a length of the slots ) ) s . ) s. In this way the adjustable height H can be determined. Most preferably the respective vertical sections llv,31v of the top and bottom bars 11,31 are sandwiched between respective sets of at least two of the side plates 22 on either sides of the vertical slots 11s, 31s held together by the bolting 25. As will be appreciated, by the bolting 25 through the side plates 22 sandwiching the vertical sections llv,31v, respective friction connections are formed with at least two frictional surfaces F on either side of the vertical sections llv,31v. That is the frictional surfaces are formed between each side of the respective vertical section llv,31v and side plate 22 for the carrying C of the top part 10 of the frame ) ( ( while maintaining the specific position AH of the bolting , 1 along the slots 11s, 31s. Alternatively, or additionally, it can also be envisaged to sandwich one or more side plates between respective sets of bottom bars and/or top bars.

As described herein, the vibration sensitive machine may generally refer to a machine that is sensitive to vibrations, e.g. negatively affecting operation of the machine when it experiences a vibrational amplitude of more than hundred micrometer, more than ten micrometer, or even more than one micrometer, e.g. in a frequency range above one hertz, ten hertz, hundred hertz, or one kilohertz, or more. For example, such vibrations which may occur in a building due to environmental circumstances, e.g. caused by vibration sources in the building itself or adjacent to the building such as traffic. For example, the vibration sensitive machine 200 is an optical device, e.g. lithographic machine or an electron microscope wherein high precision can be achieved only if undesired vibrations are sufficiently dampened and/or at least not resonated by the frame. Typically, the vibration sensitive machine 200 can be relatively heavy, e.g. having a mass of more than hundred kilogram, more than five hundred kilogram, or even more than thousand kilograms.

In some embodiments, e.g. as shown, the vibration sensitive machine 200 is connected to the top part 10 of the frame 100, which is carried by the intermediate part 20 of the frame and supported by the bottom part 30 of the frame. Typically, the machine support frame 100 is configured to provide a relatively stiff connection between the vibration sensitive machine 200 and the building floor 300. For example, the frame as described herein preferably has a horizontal and/or vertical stiffness of more than 10 ⁷ Newton per meter, more preferably above 10 ⁸ Newton per meter, e.g. between 10 ⁸ — 10 ¹⁰ Newton per meter, or more. In a preferred embodiment, the top bars, bottom bars, optional corner bars, and side plates are essentially made from steel, or other metal.

In some embodiments, the stiffness of the frame is sufficiently high that any mechanical resonances of the combined system (frame+machine) are above a dominant frequencies of environmental vibrations. Without being bound by theory a resonance frequency w( of a mass-spring system can be calculated e g as w( = V(k/M), where k is the stiffness, and M is the mass. For example, the mass can be dominated by the mass of the top part 10 (including concrete plate 12) and/or machine 200. In a preferred embodiment, the frame has a sufficiently high stiffness (e.g. for a total mass of 1000 kg) that it can provide a (lowest) resonance frequency (in any direction) above hundred hertz, preferably above one kilohertz, most preferably above two kilohertz. In this way it may be prevented that typically environmental vibrations cause resonant behavior in the system.

In a preferred embodiment, the top part 10 of the frame 100 comprises support plate 12 onto which the vibration sensitive machine 200 can be placed, preferably fixed. Typically, the support plate 12 is formed as slab or a plate. For example, the plate has a thickness (here in Z direction) of more than ten centimeter (cm), preferably more than fifteen centimeter, e.g. between twenty and fifty centimeter. For example, the support plate 12 has a length and/or width (here in X, Y direction) of more than one meter, or more than two meter, e.g. five by ten meters.

In a preferred embodiment, e.g. as shown, a length of the side plates 20 substantially corresponds to the length and/or width of the support plate 12. For example, each side plate has a length (transverse to the height and thickness of the side plate, e.g. along X and/or Y) of at least half a meter, at least one meter, at least two meter, or more. In some embodiments, e.g. as shown in FIGs 1 and 3, each side plate is large enough to cover a respective side of the frame 100. For example, the side plates extend along the whole length and/or width of the frame. The side faces of the frame can also be subdivided to be covered by two, three, four, or more side plates. For example, this is shown in FIG 4.

In some embodiments, the side plates 22 are arranged to substantially cover each side of the frame (e.g. between the corner bars 21). For example, at least fifty percent of the total side face surface of the frame 100 is covered by a set of side plates, preferably at least eighty percent, at least ninety percent, e.g. up to hundred percent. The more surface can be covered by plate material, the better the structural integrity and/or stiffness of the frame. On the other hand, it can also be envisaged to provide one or more passages through one or more sides of the frame, e.g. one or more manholes 22h through a respective side plate 22. Preferably, the support plate 12 is relative rigid, i.e. having high stiffness. For example, the support plate 12 is made of a concrete material, preferably reinforced concrete. In some embodiments, the support plate 12 has a modulus of elasticity of more than 10 Giga-Pascal (10 ^L 10 Newton per square meter), preferably more than 20 Giga-Pascal, e.g. between thirty and fifty Giga-Pascal. In other or further embodiments, the support plate 12 has a mass of more than thousand kilograms, e.g. up to 3500 kg, or more. The stiffer the support plate the better it may withstand deformation, e.g. against a load of the machine 200.

In a preferred embodiment, vibration sensitive machine 200 is provided with mounting elements 201, e.g. legs or pillars for connection to the support plate 12. In other or further embodiments, the support plate 12 comprises (corresponding) mounting structures 12m, e.g. comprising plates of metal such as steel. For example, the mounting structures 12m, e.g. footplates comprise connection elements for connecting the mounting elements 201 to the support plate 12. In some embodiments (not shown), the mounting structures 12m extend through the support plate 12, e.g. directly connecting the machine 200 via the mounting structures to the top bars 11 and/or intermediate part 20 of the frame. For example, the mounting structures comprise a different material such as steel providing a relatively high stiffness compared to the surrounding plate material such as concrete, e.g. more than a factor two higher.

In a preferred embodiment, the support plate 12 is connected to a set of top bars 11. For example, the support plate 12 is fixedly connected to the top bars 11 at a distance H above a building floor 300. In some embodiments, the support plate 12 is glued and/or screwed to the top bars 11. In other embodiments, the support plate 12 is at least partially kept in place by its sheer weight.

In some embodiments, the top bars 11 and/or bottom bars 31 comprise horizontal sections llh,31h transverse to the vertical sections llv,31v. For example, the horizontal sections llh,31h and/or vertical sections llv,31v comprise interconnected elongate plate shapes. In a preferred embodiment, the top bars 11 and/or bottom bars 31 comprise a T- or L-profile wherein one leg of the profile forms the vertical section llv, 31v for connecting the side plates 22, and another transvers leg of the profile forms a horizontal section llh, 31h for connecting to the floor 300 and/or support plate 12.

FIGs 2A-2D illustrate variations of bottom bars 31 connected to respective side plates 22. While these figures illustrate only the bottom bars 31, the features as shown and described preferably apply mutatis mutandis to the top bars, e.g. as was previously shown in FIG 1C.

In one embodiment, e.g. as shown in FIG 2A, the bottom bars 31 comprise L-bars. In another or further embodiment, e.g. as shown in FIG 2B, the bottom bars 31 comprise T-bars. In another or further embodiment, e.g. as shown in FIG 2C, a T-bar is formed by combining two L-bars. In a preferred embodiment, a set of at least two side plates 22 is disposed on either side of the vertical section 31v of the L-bar or T-bar. It can also be envisaged to provide more than two side plates, e.g. including a third side plate 22 between two vertical sections 31v or one or more bottom bars 31, e.g. two L-bars as shown in FIG 2D, or an integrated bottom bar (not shown). As will be appreciated this configuration may double the frictional surface to carry the construction (quadruple compared to a single plate). Also more than three side plates can be used, e.g. with the top and bottom bars comprising a comb profile.

In some embodiments, at least part of the vertical section 31v may help to carry the load similar as the side plates 22. Accordingly, it is preferable that the total thickness of the vertical section 31v is similar or the same as a total thickness of the combined set of side plates 22. In one embodiment, a (total) thickness Tv of the vertical section 31v is higher than an individual thickness of the side plates 22. The thickness Tv of the vertical section 31v can also be higher than a thickness Th of the horizontal section 31h. For example, the side plates 22 have an individual thickness between 5 — 20 mm, e.g. 10 mm. For example, the thickness Tv of the vertical section 31v is between 10 — 40 mm, e.g. 20 mm. For example, the thickness Th of the horizontal section 31h is between 5 — 20 mm, e.g. 10 mm.

In a preferred embodiment, the vertical sections 31v comprise elongate slots 31s there through, e.g. having a length greater than a width by at least a factor two, three, five, ten, twenty, thirty, fifty, or more. The longer the slot, the more the adjustable range. For example, each slot has a width between 5 — 40 mm, preferably between 10 — 30 mm, Preferably, the slots are arranged side-by-side with a center-to-center distance between two and four times the slot width, or a side-to-side distance (of plate material between the slots) between one and three times the slot width. For example, center-to-center between slots is between 25 — 100 mm. For example, a side- to-side distance of plate material between the slots is between 10 — 80 mm, preferably between 20 — 60 mm.

In a preferred embodiment, the side plates 22 comprise round through holes 22h, at respective positions corresponding to the slots. For example, the round holes can have a diameter which is the same or similar as the respective width of the slots. In another or further preferred embodiment, the side plates 22 are held together sandwiching the vertical section 31v by bolting 25. Most preferably, the bolt extends through the elongate vertical slot 31s as well as the through holes 22h of the side plates on either side. In other words each bolting 25 goes through the entire sandwich of the set of side plates and respective vertical section. In one embodiment, the bolt 25 comprises a nut and screw connections. Preferably, the nut is disposed on an outside of the frame so in can be tightened from the outside where it is easy to access. Also other types of connections can be envisaged.

FIGs 3 A- 3D illustrate one method of a manufacturing or assembling a modular machine support frame (here still without the top support plate). Various zoomed in sections illustrate further details as described herein.

In one embodiment, the frame is assembled to support a vibration sensitive machine at a specific height H above a floor. In some embodiments, the assembly comprises connecting a set of horizontally elongate bottom bars 31 to the floor 300 to form a bottom part 30 of the frame 100, e.g. as shown in FIG 3A. In other or further embodiments, assembly comprises connecting a set of vertically extending side plates 22 to the bottom parts 10,30 to form an intermediate part 20 of the frame 100, e.g. as shown in FIG 3C. In other or further embodiments, the assembly comprises connecting a set of horizontally elongate top bars 11 to the side plates 22, e.g. as shown in FIG 3D. In one embodiment, the elongate top bars 11 are connected to a bottom of a horizontally extending support plate (not shown here). For example, the top bars 11 and support plate together form a top part 10 of the frame 100.

In some embodiments, e.g. as illustrated in FIG 3B, the machine support frame additionally comprises a set of vertically extending corner bars 21. Preferably, each corner bar comprises a corner profile (e.g. L- shaped , preferably T-shaped) interconnecting a set of transversely oriented bottom bars 31 at the bottom part 30 of the frame and/or interconnecting a set of transversely oriented top bars 11 at the top part 10 of the frame 100. For example, the corner bars 21 can interconnect the vertical sections of respective bottom bars, or top bars by being bolted to respective slots 11s, 31s. In a preferred embodiment, the corner bars 21 also form an interconnection between the top and bottom parts 10,30. In this way, the corner bars 21 can also carry part of the load together with the side plates. Most preferably, the corner bars 21 are disposed in the same plane as one of the side plates, i.e. bolted side by side. In other words, the corner bars 21 are preferably not between the side plates 22 and the vertical section 31v. Instead the corner bars 21 may be considered as a corner extension of the side plates 22. The term corner may include an inner corner, e.g. in the middle of the frame as shown in the figures.

In some embodiments, the top bars 11 and/or bottom bars 31 are cut to size for providing the frame with a specific length and/or width. Advantageously, the bars can be cut during assembly, i.e. at the assembly site as opposed to during fabrication. For example, the top bars 11 and/or bottom bars 31 are cut to length to match with the support plate 12. Also the corner bars 21 may be cut to length. It can also be envisaged to use identical parts for constructing the top bars, the bottom bars and side bars, e.g. cut to different lengths. In some embodiments, an inside of the frame ) ( ( may be divided by a set on inner side plates , , ’ having similar function and connection as the outer side plates 22. For example, a set of inner side plates , , ’ may sandwich a respective inner bottom bar The one or more inner side plates 22 may provide additional support, especially when the frame 100 has a length X greater than its width Y.

FIGs 4A-4D illustrate another or further method of assembling the frame. In one embodiment, e.g. as shown, the top bars 11 are integrated into the support plate 12. For example, the support plate 12 comprises a concrete block wherein parts of the top bars 11 are cast into the concrete. Also, other integrated constructions can be envisaged, e.g. top bars welded to a metal top plate. In another or further embodiment, e.g. as shown, the frame is assembled by lifting the support plate 12 at a specific height above the floor, and assembling the other parts in reverse order. For example, a set of vertical bars 21 and/or side plates 22 is connected to the top bars 11, and a set of side bottom bars 31 is connected to the side plates 22. Also other sequences can be envisaged.

FIG 5 illustrate various heights obtainable by a limited set of different side plate heights connected at a variable height between respective top and bottom bars;

As described herein, typical plate heights of the side plates are between 200 — 1200 mm, preferably between 300 — 1000 mm. For example, each side plate has a minimum length and height (width) of at least 300 mm, preferably at least 400 mm, and a thickness of at least 5 mm. The specific length of the side plates can depend on the desired length and/or width of the frame. The specific height (width) of the side plates can depend on the desired height of the frame. In one embodiment, heights between 250 — 400 mm are obtained by directly connecting the top bars 11 to at a variable height to the bottom bars 31, e.g. without any side plates. In another or further embodiment, heights between 440 — 700 mm are obtained by inserting a first set of side plates with plate height 360 mm. In another or further embodiment, heights between 670 — 970 mm are obtained by inserting a second set of side plates with plate height 630 mm. In another or further embodiment, heights between 940 — 1240 mm are obtained by inserting a third set of side plates with plate height 900mm. So it will be appreciated that a continuous range of heights can be achieved using a limited set of stock plates.

In some embodiments, where the slots may not extend all the way to the end of the vertical sections, there can be a gap in obtainable height between 400 — 440 mm To resolve this the inset “V” illustrates an embodiment, wherein the slots 11s, 31s extend from an undulating or saw tooth profile at a bottom or top end of the respective vertical sections llv,31v on the top and bottom bars 11,31, wherein the undulating profile of the top bars 11 fits into the undulating profile of the bottom bars 31 to allow a bottom end of respective slots 11s on the top bars 11 to be set at a same height or below a top end of respective slots 31s on bottom bars when the vertical sections llv,31v are disposed in the same plane.

In one aspect, the present methods and systems may be embodied as a corresponding kit of parts for assembling the modular machine support frame as described herein. For example, the kit of part comprises a limited set of top bars and bottom bars, which may be all the same length and cut to size, as needed. For example, the kit of parts may also comprise corner bars which can also be the same, or different. For example, the kit of parts may comprise a limited set of side plates with (discrete) different heights, e.g. wherein the height interval is the same or a bit less than the total length of the slots in both the bottom and top bars, e.g. wherein the height difference of the plates is between 0.8 and 1.0 times the total slot length (or half length of the individual slots).

FIGs 6A and 6B illustrate a load L applied to a corner of the frame 100, and calculated shearing forces for different bolting positions X,Y along the frame. In the calculation shown, a load L with a force of 1000 Newton was applied to the corner, resulting in the shown distribution of forces. The graph shows the forces between the plates 22 and inside and outside the top bars ) ) with markers “x” and “o” respectively In this case a max total shear force of 61 N + 59 N = 120 N, was observed. In another calculation with a much higher load of 150 kilo Newton, a max shear force of 17.95 kN was observed.

By increased tightening of the bolting 25, friction between the touching surfaces of the side plates and vertical section of the top/bottom bars can be increased. Preferably, the bolt is tightened to prevent slipping of the surfaces. For example, each bolt is able to provide the at least two sets of touching surfaces with sufficient friction there between to withstand a respective downward load or shear force without slipping of at least hundred Newton, preferably at least thousand Newton, or even more than ten thousand Newton.

In some embodiments, sufficient friction is be achieved by tightened the bolts e.g. until a fastening tool measures a predetermined torque. For example, High Resistance Calibrated (HRC) and/or Tension Controlled Bolts (TCB) can be used. In other or further embodiments, the surfaces of one or both of the vertical sections and/or side plates are treated to increase friction. In one embodiment, the surfaces are roughened by a treatment such as (sand)blasting and/or spraying. For example, a zinc spray can be used. In another or further embodiment, it can also be envisaged to provide the surfaces with a corrugated profile which can lock the surfaces together at a specific height.

In some embodiments, the slots orientation of slots is diagonal, i.e. having not only a vertical component for the height adjustment but also a horizontal component whereby the bolt can partly rest on the slanted surface of the slot. For example, the slots are at an angle of at least five degrees with respect to a normal of the floor surface, e.g. between ten and forty five degrees. The higher the angle of the slots, the more the slanted slot surface may carry part of the load in addition to the frictional surfaces, although at the cost of height range.

In a preferred embodiment, as shown throughout the figures, each set of side plates 22 is held together by a plurality of bolts through a corresponding plurality of slots 11s, 31s. To distribute the forces, it is preferable on the one hand to provide a relative high density of bolts connecting the plates to the top and bottom bars. On the other hand, increasing the number of bolts may correspond to a similarly increased number of slots in each of the top bars 11 and bottom bars 31, which may weaken their structure. Based on the calculations, the inventors find it preferable that the side plates 22 are respectively bolted to the top bars 11 and/or bottom bars 31 with a density between a minimum and maximum number of bolts per meter (per top or bottom bar). Specifically, the inventors find it advantageously to use between five and fifty bolts/slots per meter, preferably between ten and forty bolts/slots per meter (i.e. a row of adjacent bolts with a center-to-center distance between 25 — 100 mm), preferably between twenty and thirty(i.e. center-to-center distance between 33 — 50 mm). For example, each plate is bolted by a set of at least three, four, five, ten, or more, adjacent bolts through a corresponding set of adjacent holes and slots in the respective side plate and respective vertical section of the top or bottom bar. For example, the illustrated embodiment has a bolting density about twenty-five bolts and slots per meter per bar, i.e. a row of adjacent bolts with a center-to-center distance of about four centimeters.

For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described. For example, plates and bars may be combined or split up into one or more alternative components. The various elements of the embodiments as discussed and shown offer certain advantages, such as adjustability of various dimensions. Of course, it is to be appreciated that any one of the above embodiments or processes may be combined with one or more other embodiments or processes to provide even further improvements in finding and matching designs and advantages. It is appreciated that this disclosure offers particular advantages to machine support frames, and in general can be applied for any application wherein a stiff and adjustable support structure is desired.

In interpreting the appended claims, it should be understood that the word "comprising" does not exclude the presence of other elements or acts than those listed in a given claim; the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements; any reference signs in the claims do not limit their scope; several "means" may be represented by the same or different item(s) or implemented structure or function; any of the disclosed devices or portions thereof may be combined together or separated into further portions unless specifically stated otherwise. Where one claim refers to another claim, this may indicate synergetic advantage achieved by the combination of their respective features. But the mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot also be used to advantage. The present embodiments may thus include all working combinations of the claims wherein each claim can in principle refer to any preceding claim unless clearly excluded by context.