Field of the Invention The field of the invention is manufacture of structural objects.

Background of the Invention Boxes, counter-tops, shower basins, and many other structural objects involve a joint of material in three different planes. In boxes having both tops and bottoms, for example, there are eight three-plane joints, one at each corner. In counter-tops there is frequently only one three-plane joint, typically where two perpendicular backsplash portions intersect with a horizontal deck. In shower basins, there are usually four three-plane joints, with one at each corner.

Three-plane joints are generally manufactured by butt-joining or folding material to produce a two-plane joint, and then attaching the third plane of material in a subsequent step. In the manufacture of boxes, for example, it is known to place three grooves perpendicular to the long axis in a sheet of material, fold the sheet at the grooves, and then glue the ends together to produce four two-plane joints connecting the four sides of the box. To produce the three-plane joints, a top and a bottom are then glued onto the open ends of the four sides. In the production of kitchen countertops, a sheet of plastic solid surface cutting material such as Coran, Fountainhead'M, Avonite, Gibraltar or Swan Stone is often grooved parallel to its long axis about five inches from one of the sides. The sheet is then folded along the groove to produce a relatively wide deck area and a perpendicular backsplash. The backsplash is placed along one wall of the kitchen, with one end of the deck butted against an adjacent, perpendicular wall. Since the end of the deck abutting the wall has no backsplash, a separately cut backsplash piece is glued to both the end of the deck and the end of the backsplash to form the three-plane joint.

Three-plane joints need not necessarily contain material at three mutually perpendicular orientations, and three-pane joints having such out-of-square corners are especially difficult to manufacture. This problem is of more than academic interest because the supposedly perpendicular walls in many houses and other buildings are often up to 5 ° out of square, and thus approach one another at an angle of between 85 ° and 95 °. The problem is often exacerbated because one or both of the intersecting walls is also off-vertical by up to 5 °. These conditions have previously made it virtually impossible to provide"pre-fab"three-plane countertops which can be installed by non- professionals.

In addition to that just mentioned, another problem arises in attempting to provide countertops and'other structures with three-plane joints is the inclusion in the structure of coved two-plane joints. Coved two-plane joints, which are also known as radius interior corner joints, or "soft corners"have a smooth transition from one plane to another, rather than an abrupt or"hard corner". Kitchen counter-tops, for example, are often manufactured with coved joints because the coves are visually more appealing, and easier to clean.

Coved joints are also more expensive to produce. Manufacturing technique commonly begin with butt joining two pieces together, or placing a"v"groove in a single piece of sheeted material, and then folding the material at the groove to form a hard corner. A long square insert is then glued in place along the entire length of the corner, and routed to form the cove. While conceptually simple to fabricate, countertops produced in this manner may be undesirable because, among other things, the additional labor involved increases the cost of the final product, and the seams may be relatively weak or visibly poor. Another known method involves countersinking the lengthwise bottom edge of the backsplash piece and an overhanging edge of an elongated rectangular strip into a rabbet formed along the upper lengthwise back edge of the deck. A portion of the rectangular strip is then mechanically removed using either before or after it is glued, a router to define the coved joint. Both of these methods, however, are time-consuming and require considerable skill.

A better method of producing two-plane coved joints uses a combination cutter to produce two parallel"v"grooves in the material, while at the same time routing a cove between the grooves.

Simply folding the material along the grooves produces the cove. This method has the definite advantages of avoiding any additional routing and gluing steps, ensuring that the cove is uniform, and generally providing a much stronger joint.

Despite the clear advantages of producing two-plane coved joints by folding a single piece of sheeted material, the present applicant is unaware of any teaching or suggestion for extending this concept to three-plane joints. The present applicant is also unaware of any methods for producing such joints which can readily accommodate out of square walls. Thus, there is a need for simple and cost-effective methods and apparatus for producing three-plane joints, especially three-plane coved joints, and most especially three-plane coved joints in which the planes are not normal to each other (i. e., are not mutually perpendicular).

Summary of the Invention The present invention is directed to methods, apparatus and products in which a three-plane joint is fabricated by parallel grooving a sheet to define multiple sections, removing some of the pieces, completing a potential void which would otherwise exist when the remaining pieces are folded or otherwise juxtaposed, and juxtaposing the remaining pieces to produce the three-plane joint.

The void is preferably completed according to any of three classes of methods. In a first class of methods a triangular center block is inserted into the corner void. In a second class of methods the void is enlarged and the enlarged void is completed with a filler pieces. In a third class of methods, the corner void and portions of several of the remaining pieces are cut away, and a filler piece is placed across the cut.

In one class of preferred embodiments, the structure comprises a countertop having at least two backsplash/deck joints, and at least one three-plane joint coupling the deck with two substantially perpendicular backsplashes. In more preferred embodiments of the class one or both of the backsplash/deck and backsplash/backsplash joints are coved, and in still more preferred embodiments of the class the deck additionally includes an overhanging edge joint.

In an analogous class of shower basins, the basin comprises a deck coupled with at least four coved sides using coved joints, and the vertical joints coupling the sides are also coved.

Various objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, along with the accompanying drawings in which like numerals represent like components.

Brief Description of the Drawings Figure I is a perspective view of a sheet having double cross grooves.

Figure 2 is a perspective view of the sheet of Figure 1 folded to form a three-plane joint.

Figure 3A is a perspective view of a triangular center block.

Figure 3B is a plan view of the triangular center block of Figure 3A.

Figure 3C is a side view of the triangular center block of Figure 3 A.

Figure 4 is a perspective rear view of the folded sheet of Figure 2 with the rear opening of the triangular corner void.

Figure 5 is a plan view of the folded sheet of Figure 2, showing a line of minimal cut to remove the void and relative cut pieces.

Figure 6A is a plan view of the folded sheet of Figure 2 with the addition of a filler piece that replaces the volume removed by the cut of Figure 5.

Figure 6B is a plan view of an alternative folded sheet that replaces a larger volume than that removed by the cut of Figure 5.

Figure 7 is a perspective view of the folded sheet of Figure 2 wherein the vertical corner has been replaced with a rounded corner section.

Figure 8 is a perspective view of three backsplash/cove sections joined together to receive a mating field.

Figure 9A is a plan view of the unfolded backsplash/cove sections which can be folded to achieve the configuration of Figure 9A.

Figure 9B is a side view of the folded backsplash/cove section and field of Figure 8.

Figure 10 is a bottom view of a sheet of material with double cross-grooves to produce the backsplash/cove sections and indexed edge of Figure 8.

Figure 11 is a cross-sectional view of a cutter set mounted on an axle.

Figure 12 is an enlarged cross-sectional view of a cutter tip of Figure 11.

Figure 13A is a plan view of a double cross-grooved first sheet of material which will be folded to fit to out-of-square walls.

Figure 13B is a plan view of the first sheet of Figure 13A, along with a second sheet double grooved and cross-cut to mate with the first sheet.

Figure 13C is a plan view of the first and second sheets of Figures 13A and 13B, respectively, folded and fitted to a corner having out-of square walls.

Figure 14A is a perspective view of sheet of material including first and second"V"grooves defining two outer and one intermediate pieces.

Figure 14B is a plan view of the sheet of Figure 14A in which one of the outer pieces is removed, and third and fourth"V"'grooves have been made.

Figure 14C is a perspective view of the material of Figure 14B in a folded configuration.

Figure 14D is a perspective view of the material of Figure 14A cut and folded in an alternative manner.

Detailed Description As used herein, the terms"countertop"and"countertops"refer to any elongated work space such as may be found in kitchens, bathrooms, workshops, offices, and many other locations.

Countertops do not necessarily imply an underlying cabinet, and therefore include commercial bathroom"Pullman"type counters in which the counter portion is held in position via some combination of legs and wall brackets, rather than by an underlying cabinet. Countertops vary greatly in complexity from something as simple as an elongated piece of plywood, to something as complex as a unitized solid piece of plastic having a backsplash, overhanging edge, sink or other cutout, and involving one or more corners.

Also as used herein, the term field refers to a section of building material which has a large surface area relative to other sections. In countertops, for example, the field is the substantially horizontal deck or work surface, and in shower basins, the field is the substantially horizontal standing surface. The field does not have to be horizontal, however, and it is contemplated for example that the field could comprise the vertical or off-vertical backing of a television set, or a bookshelf.

As used herein, the term"sheet"refers to a broad structure in which the longest and widest dimensions are each at least ten times the smallest thickness. Sheets need not be completely planar, and may instead include at least some portions which are rolled, twisted, or warped, and may also include one or more projections or extrusions such as texturing or edge lips. It is also not necessary for sheets to be completely smooth. In fact, many commercially available sheets used in the fabrication of countertops are finished on only one side. The sheets of Figures 1-4, are preferably predominantly planar structures measuring about 30 inches wide by 12 feet long by 1/4 to 3/4 inches thick, and are preferably manufactured from a plastic solid surfacing material such as CorianTM,

Fountainhead and Surely. Other sheeted materials may also be used, however, including wood, laminated plastics or woods, and even stones such as granite or marble.

As used herein the term"groove"refers to an elongated, narrow channel or depression, such as would be produced by cutting into a sheet during relative translation between the sheet and a cutter or router. A groove placed in a material defines at least two sections of the material, one on either side of the groove. More than two sections are formed where the groove crosses either a break or cut in the material, or another groove. Placing a groove in a sheet is distinguished herein from cutting a sheet into two or more pieces by the presence of a continuing physical coupling of the sections produced by the grooving. Thus, for example, in fabricating a sheet of PSSM for use as a countertop, one side is often taped, and then the sheet is grooved from the opposite side to within a few thousandths of an inch of the tape. In some cases the sheet is grooved to an even closer tolerance, and the sheet may even be grooved all the way through to the backing tape, lamination, or other connecting composition.

The grooves contemplated herein may have many different cross-sectional shapes, including "V","U", and notch shapes, and may even have different cross-sectional shapes at different lineal positions."'shaped grooves often define a total groove angle of between about 30° to about 120°, although most"V"grooves discussed herein preferably define a total groove angle of about 45°. The two sides of"V'groove could have different lengths, and therefore define different half- angles relative to the apex. In many instances of"V"grooves having a total groove angle of 45°, for example, the two sides may form 18° and 27° half-angles, respectively.

The shape of a groove utilized in production of a joint largely determines the shape of the resulting joint. Thus, for example, simple"V"grooves produce simple mitered joints, while a more complex groove may produce a mitre-lock joint (also referred to herein as a stair-stepped joint). In general, simple mitered joints are satisfactory for many applications, but are less strong than mitre- lock joints because they involve less surface area in which to apply an adhesive or other bonding agent.

Once one or more grooves have been provided in a sheet or other workpiece, whether by cutting, routing or some other means, the workpiece is folded at one or more of the grooves to form a joint. As used herein the term"folding... at a groove"means that at least two sidewalls of the groove are juxtaposed, and depending on the depth of the groove relative to the thickness of the workpiece, the juxtaposition may involve bending of the workpiece proper, a supporting structure such as tape or lamination, or some combination of the two. Thus, as used herein, the term"folding" is meant as a species of the more generic term"juxtaposing."It is not necessary for folding at one or more grooves to produce 90° joints. A sophisticated shower or bath tub basin, for example, may have eight sides in which the joints are all approximately 45°. In other applications, such as the joining of two separate sheets, grooves may provide substantially 180° joints. Even in countertops the backsplash and overhanging edge joints may vary up to 30° or more from the standard inside joint angle of 90°, i. e. and 60°.

The shape of the joint (s) produced during folding is related to the number and dimensions of the corresponding groove (s), and also to the shape (s) of any sections adjacent the groove (s). For example, the recess formed between parallel grooves of a cove joint assists in providing the overall coved appearances. Such recesses are often given in terms of radius, with a preferred radius for countertops and other applications being between about 1/16 inch and about 5/8 inch, with the most common radius being either 3/8 inch or 1/2 inch. In addition to variations in the curvature, recesses used in forming coves may also vary in depth.

Referring first to Figure 1, a sheet 10 to be manufactured into a countertop is divided into nine sections 12,14A, 14B, 14C, 14D, 16A, 16B, 17 and 18 by two grooves 20A and 20B in one direction and two grooves 20C and 20D in another, preferably perpendicular direction. As can be appreciated from Figure 1, section 12 is the field, sections 14A, 14B, 14C and 14D are coves, sections 16A and 16B are backsplashes, section 17 is a corner block, and section 18 is a rectangular center block.

Since the present subject matter has application to other structures besides countertops, backslash sections 16A and 16B may also be generically referred to herein as shoulder pieces, cove

sections 14A and 14B may also be generically referred to herein as long intermediate pieces, cove sections 14C and 14D may also be generically referred to herein as short intermediate pieces, corner block 17 may also be generically referred to herein as a head piece, and, rectangular center block 18 may also be generically referred to herein merely as a center block.

In Figure 2 the corner block 17 and center block 18 have been removed, as well as cove section 14D, and the remaining sections have been folded along grooves 20A, 20B, 20C and 20D.

This leaves a triangular corner void 22, which can be completed according to any of three conceptually different classes of methods. In a first class of methods the void is filled with a new piece. The filing can take place in many different manners, including inserting a new, precut or preformed piece of the proper size, inserting a larger piece in the void and then reducing the excess, and inserting a liquid or otherwise moldable piece into the void. In a second class of methods, the void is enlarged or cut away to form a more convenient, generally flat surface, and then the new void or surface is completed with an appropriate piece. In a third class of methods, the entire"corner"of either a three plane joint, or what would become a three-plane joint when completed, is cut away, and the removed corner is replaced with a pre-formed, pre-cut or other piece. The new piece can be have many different configurations, including an actual corner, a two-or three-way coved corner, or even a rounded"corner".

The first class of methods of completing void 22 is exemplified in Figures 3A, 3B and 3C.

Here, a triangular center block 24 is inserted directly into the void 22. It will be appreciated from Figures 3A and 3C that each of the sides 24A, 24B and 24C of triangular center block 24 is preferably angled 22.5° off vertical to mate with cove sections 14A, 14B and 14C, and that the top 24D has a three-way saddle shape. Similarly, from plan view Figure 3B it will be appreciated that triangular center block 24 appears as an en equilateral triangle, with each of the sides 24A, 24B and 24C having substantially the same lengths.

Triangular center block 24 can be produced in many different ways. Where the sheeted material is a moldable material such as a plastic solid surface plastic material or a metal, block 24 is preferably molded. In some cases, the molding can even take place in situ, as where the corner is

filled with a resin which is then hardened. In other instances, an oversize center block can be inserted into the void, and then cut away from one end or the other. In still other instances, such as where the block 24 comprises wood or stone, block 24 is preferably cut to an approximately correct size prior to installation from a scrap piece of material such as an end of cove section 14D. Triangular center block 24 is preferably maintained in position in void 22 by gluing. Once in place, triangular center block 24 can be routed or sanded, to form a smooth transition with adjacent sections.

The second class of methods of completing void 22 is exemplified by Figure 4. Here, a double compound cut 30 is used to enlarge the void 22. Cut 30 is considered to be double compound because it neither aligns vertically with respect to backsplashes 16A and 16B, nor horizontally with respect to field 12. For convenience, double compound cut 30 is preferably 45° off vertical with respect to each of backsplashes 16A, 16B and field 12. Once cut 30 is made, a small filler piece (not shown) is set across the cut 30 to cap the enlarged void. Filler piece (not shown) is preferably a flat piece of scrap, and presumably would comprise the same material used elsewhere.

The third class of methods of completing void 22 is exemplified by Figures 5,6A and 6B. In Figure 5, a cut 30 is made across backsplashes 16A, 16B and cove sections 14A, 14B, thereby completely removing cove section 14C, and thereby eliminating void 22. Cut 30, as well as several other cuts described herein, can be made while the material is still relatively flat, or preferably after folding along the various grooves. In Figure 6A, a large filler block 42 is set across cut 30 to complete the three-plane intersection. The large filler block 42 is preferably a flat piece of scrap, and presumably would comprise the same material used elsewhere. In Figure 6B, two filler blocks 42A, 42B are employed, with block 42A having substantially flat sides and block 42B having an enlarged radius.

This third class of methods is particularly adaptable to handling out of square corner conditions, which are the rule rather than the exception, especially in tract homes. Such conditions can be taken care of by modifying the angle of cut 30 relative to pieces 16A and 14A on the one hand, and 16B and 14B on the other hand. In general, the modification will substantially divide the

actual corner angle. Thus, depending upon the squareness of the walls leading to the corner, filler block 42 may at an angle of 45 * A/2 where A amount by which the walls are out of square.

It is also important to note that in this method, as in all of the other methods described herein, there are numerous possible modifications, without departing from the inventive concept. For example, filler block 42 is described as a single piece with respect to the drawing, but in fact it may comprise multiple pieces 42A and 42B as shown in Figure 6B. As another example, Figure 5, cut 30 could be place farther away from the corner than shown, such that the developed corner has a flattened portion, at about 45 ° relative to each of the sides 16A and 16B. This flattened portion can be larger or smaller than that shown in Figure 6B, and may be covered or patterned in some other manner, as shown in Figure 6C.

Figure 7 illustrates a variant on the third class of methods of completing void 22. Here, two cuts 50A, 50B are made-cut 50A across backsplash 14A and cove piece 16A, and cut 50B across backsplash 14B and 16B. These cuts can be normal to the pieces being cut, or at some other angle.

Cuts 50A, 50B may or may not cut into field 12. Once cuts 50A, 50B are made and the small pieces removed, a corner section 55 can be attached as shown. It is contemplated that corner section 55 would be molded, and provided as a single piece to be glued or otherwise attached between pieces 16A and 16B.

Figure 8 illustrates an alternative method of making a countertop, shower basin or other structure having a three-plane joint. In this method one or more sheets of material is double grooved and folded to form a backsplash/cove section. Two or more backsplash/cove sections are then butt joined and glued together. In Figure 8 there are three backsplash/cove sections 60A, 60B, 60C joined together at joints 62A and 62B. Each of sections 60A, 60B and 60C have an indexed edge 65. Indexed edge 65 would generally be used to mate with a corresponding indexed edge similar to 9B) on the field 12, and thereby cooperate to line up the field 12 with the joined backsplash/cove sections 60A, 60B, 60C. Of course, one or both sides of cuts 62A, 62B on backsplash pieces 60A, 60B may also be indexed to mate with corresponding edges on the sides of the corner backsplash cove piece 60B.

Figures 9A and 9B an alternative method of preparing the a corner piece having the overall appearance of Figure 8. In Figure 9A a sheet of material is cut to have an indexed edge 65. The material is then"V"grooved at groove 66, the parts on either side are folded together at the groove 66. Two additional grooves 67A and 67B are then made perpendicular to groove 66, which effectively divides the material into backsplash sections 72A, 72B and 72, and cove sections 74A, 74B and 74C. The combined backsplash/cove 60A (seen in side view in Figure 9B) is then ready to mate with a field (not shown) having corresponding indexed edges.

In Figure 10 a sheet of material is double cross-grooved with grooves 67A, 67B, 65 and 66 to produce the backsplash/cove sections 60A, 60B, 60C and indexed edge 65. When folded, backsplash portion 72A and cove portion 74A combine to form backspash/cove piece 70A similar to 60A in figure 8 60B, while backsplash portion 72B and cove portion 74B combine to form backspash/cove piece 70B (see figure 8), and backsplash portion 72C and cove portion 74C combine to form backspash/cove piece 70C (see figure 8).

Figure 11 illustrates a cutter 100 set capable of producing the double grooves contemplated herein. The cutter set 100 is journaled on rotating shaft 105, and generally comprises a support 110 two mirror image cutting tips 120, and optional coving cutter 121. Each of the cutting tips 120 has an apex 122, a projecting section 124 and a receiving section 126, the latter two of which produce indexed sides which can be joined to produce a stepped lock joint. The 22.5° off-normal angles specified in Figure 11 are preferred angles only, and it will be appreciated that other angles are possible, although for each groove being produced, the total of the off-normal angles for any given cutting tip is usually 45°. This feature is illustrated in Figure 12 wherein the total arc line 128 is usually 45°.

Techniques for manufacture of appropriate cutter sets are known. In general the cutting tips will comprise a hardened metal such as C-4 carbide, and may alternatively include a diamond or other coating to increase wear. The shape of the cutting tips can be provided by grinding or other methods such as laser cutting or E. D. M.

Of course it is possible to place substantially parallel grooves in a sheet of material using methods and apparatus other than cutters. It might, for example, be possible to rout the grooves, to etch out the grooves using some sort of acid, abrasive or intense laser, or even to mold the grooves.

Figures 13A, 13B and 13C illustrate another method of producing three-plane joints for out-of-square walls. In Figure 13A two walls 592 and 692. (see Figure 13C) intersect in a corner (not shown) at an angle greater or smaller than 90°, i. e., 90° plus A where A is greater than zero. It is specifically contemplated that this method may employed for A of at least 2°, and for A of at least 4°. For the sake of clarity, A is shown in Figures 13A, 13B and 13C as about 10-15 °, and although A will almost always be less than about 5°, such large values of A are entirely possible.

In a particularly preferred embodiment a sheet 500 having substantially square side edges is double grooved at 520A and 520B, and then double cross-grooved at 520C and 520D at an angle of 90° + A. These four grooves 520A, 520B, 520C and 520D divide the sheet into backsplash sections 516A and 516B, cove sections 514A, 514B, 514C and 514D, field section 512, corner block 517 and corner block 518. A cut is also made in sheet 500 at dotted line 523, which is parallel to grooves 520C and 520D. In this manner, angles 519A and 519B both preferably measure 90-A°, while angles 521A and 521B both measure approximately 90+A°. If the grooves 520C and 520D intersect with grooves 520A and 520B to product an angle less than 90°-A, then 521 A and B are less than 90°-A, and 519 A& B are greater than 90°-A.

In Figure 13B, another sheet 600 having substantially parallel side edges 601,602,603 and 604, is double grooved at grooves 620C and 620D, at the same relative spacing as grooves 520C and 520D as shown, and substantially parallel to the side edge 601. This produces backsplash section 616, cove section 614 and field section 612. A cut is made in sheet 600 at dotted line 630, such that the new edge formed is off perpendicular to edge 601 by 0 °.

In Figure 13C, one of cove sections 514C and 514D, corner block 517 and center block 518 have all been removed, the remaining pieces of sheet 500 have been folded together, and the resulting void 542 has been completed using one of the methods discussed above with respect to Figure 6A or B. Sections 612,614 and 616 are also folded together, and fields 512 and 612 are butt joined as

shown. In this manner, the entire countertop fits properly into out-of-square corner walls 592 and 692. While no longer present, phantom lines 523A and 623A show where sheets 500 and 600 would have extended had they not been altered to compensate for the out-of-square walls 592,692.

Other configurations, of course, are also contemplated, such as employing the methods corresponding to the above-described methods where A is less than zero.

Figures 14A, 14B, 14C and 14D depict yet additional methods of producing a three-plane joint. In one variant a sheet is double grooved to form three pieces, one of the outer pieces is removed and the remaining two pieces are folded together. The folded piece is then double grooved in a perpendicular or off-perpendicular direction to define six pieces, and the six pieces are folded together to produce the desired corner. In another variant, one of the outer pieces is folded away from the adjacent groove while the other outer piece is folded into its adjacent groove. The cross- grooving is performed on the folded together pieces, and only then is the folded under piece removed from the other pieces. In that variant the grooving and cross-grooving would have produced seven pieces which were all coupled together at some point in time. Regardless of the variant used, cross- grooving in an off-perpendicular direction is useful in accommodating an out-of-square corner condition.

Considering this method in further detail in Figure 14A, a sheet of material 300 has been grooved by a first"V"groove 310A, and a second"V"groove 3 IOB. Obviously, grooves 310A and 31 OB can be grooved at the same time or at different times. These grooves 310A, 31 OB cooperate to define outer pieces 314 and 316, and an intermediate piece 315. Additionally, intermediate piece 315 may or may not be coved, and such coving could be accomplished by many means.

The grooving and coving are preferably produced using a single pass with a multi-part cutter/groover set as known in the industry. The single pass is especially preferred where the material is a hard plastic as discussed above, or is otherwise unwieldy or difficult to fabricate. The material, of course, need not comprise a hard plastic, and need not have any utility at all with respect to counter-tops or shower surrounds. The material may, for example, be suitable for producing a wooden or other box. As discussed above, there are numerous alternatives in the shape and size of

the groove, but typically the grooves are"V"grooves, with each groove totaling 45°plus or minus.

The cove is entirely optional, and where present there are also numerous alternatives. Typically, a cove would be similar to those found on known counter-tops.

In Figure 14B the outer piece 316 has been is removed, and third groove 310C and fourth groove 31 OD"V"grooves have been made perpendicular to the first and second grooves 310A, 310B. This operation results in six distinguishable pieces, 320,322,324,326,328 and 330. The word"distinguishable"is used here to denote that the pieces defined by the grooving are not necessary completely separate. In preferred embodiments of this method, as with other embodiments discussed herein, the various pieces are likely to be held together with a tape backing. In other embodiments, especially when dealing with suitable materials, the various pieces may be held together by virtue of the fact that the groover blades did not entirely cut through the material. In still other embodiments, the various pieces may be entirely separated by the groover blades, or by some other procedure, and the parts are merely held together by hand, or in a mold, or in some other manner. In still other embodiments, it is contemplated that the six pieces 320,322,324,326,328 and 330 may even be further subdivided or otherwise modified. In Figure 14C the six distinguishable is a perspective view of the material of Figure 14 in a folded configuration.

As noted briefly above, the method being described is extremely variable. As a single example, it is contemplated to separate such grooves 3 IOC and 3 IOD by a greater space. This would yield a"corner"having a flattened corner section such as that shown in Figure 14D. In other alternatives, the long free edges of pieces 320 and 328 may either be flat, or may be cut to have some sort of locking pattern with a counter top, shower stall bottom or other field (not shown).

One will, of course, note that then end results shown in Figures 8 and 14D are quite similar, even though the methods are quite different. To clarify, the methods of Figure 8 generally start out with a two part backsplash/cove 60A, 60C, and the intersection is cut away to insert a separately formed corner piece 60B. In other embodiments, three backsplash/cove pieces 60A, 60B and 60C are prepared separately and then joined together. In the methods of Figure 14D, all the pieces are formed from a single sheet, and then folded together.

Thus, specific methods and apparatus for double cross-grooving have been disclosed. It should be apparent to those skilled in the art, however, that many more modifications besides those already described are possible without departing from the inventive concepts herein. For example, the descriptions herein could be applied to triple cross-grooving as well as double cross-grooving.

Also the various cuts contemplated herein could be produced by individual cutters rather than cutter sets as illustrated. Still further, all of the double grooving may or may not include intermediate coving or other surfacing, and the double grooves may be closer or farther apart from each other than that illustrated herein. Still further, the sheeted materials contemplated herein are not limited to that specifically described, and may instead include corrugated or flatted cardboard, or other materials which are relatively flexible. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims.