PRODUCING COMPLEX THREE DIMENSIONAL FORMS IN WOOD

Abstract: By the invention complex three-dimensional forms in wood, for example, cabriole chair legs, may be produced by a turning method on lathe possessing special characteristics. The process involves supporting a pack of wood lengths for rotation about the lathe rotational axis such that, in operation, wood is removed from the periphery of the several wood lengths of the pack by the action of a tool, such, for example, as an abrading file, the amount and distribution of the wood removed from each wood length being determined by a profile of template means and the spatial relation of the wood-length with respect thereto; displacing at least one of the wood lengths through a certain angle about its longitudinal axis and thereafter repeating the template determined wood removal step. To produce a third such surface in the aforesaid wood-lenght, the wood-length is again angularly displaced and the wood removal step repeated yet again. The template means may be constituted as two template members supported on the lathe bed or base one to either side of the lathe rotational axis.

Description: PRODUCING COMPLEX THREE DIMENSIONAL FORMS IN WOOD This invention relates to a method of and an apparatus for manufacturing complex three-dimensional forms in wood. Whilst, without confirmatory evidence, the matter must remain in the realm of speculation, it is a thesis of this specification that the generation by noted furniture manufacturers of the 18th. century and earlier of complex wood shapes, such, for examples, as cabriole legs and arm and back-pieces for chairs, was achieved not, as commonly advanced, by highly skilled wood-carvers but, rather, by poorly paid wood-workers working in ill-lit work-shops, often, during winter, in freezing conditions, in environmental conditions, that is to say, quite inimical to the wood-carvers craft. "The London Tradesman" (1747) by Robert Campbell and available records of such noted companies as Chippendale Haig, Cobb and Vile and, most notably, perhaps, Gillows, as to the numbers, rate of production and labour rates for work done in their work-shops would seem to support the thesis advanced above. According to the invention, a method of producing, in wood, artifacts of complex three-dimensional form comprises: (a) devizing template means defining a profile appropriate for surfaces to be produced in the article; (b) supporting a pack of wood lengths side-by-side lengthwise in contact with one another about a certain pack longitudinal axis; (c) rotating said pack about said pack longitudinal axis; and, (d) moving wood removal means in directions longitudinally of and radially towards said longitudinal axis such that wood is removed from each of the several wood lengths of the pack at the periphery thereof by the action of said wood removal means thereon, the amount and distribution of wood removed and the three-dimensional surfaces created in the several wood lengths of the pack as a result of such wood removal being determined by the profile of template means and its spatial relationship to said wood length. In certain cases, the method step (d) may be followed by the further steps comprising: (e) displacing at least one of said wood lengths about its individual longitudinal axis, being distinct from said pack longitudinal axis, through a predetermined angle; (f) repeating the method step (d) so as to create a second three dimensional surface in said at least one wood length; and , (g) for the creation of further three-dimensional surface portions (if any) in said wood lengths or any of them repeating method steps (c) to (e) in respect of each such surface . In other cases, the method may comprise: (i) performing method steps (a) to (d) specified above successively on a multiplicity of packs of wood-lengths; (ii) selecting from each of said packs a particular wood- length; (iii) supporting said selected wood-lengths to form a further pack with the several wood-lengths thereof angularly displaced through a certain angle with respect to one another about their longitudinal axes such as to expose, on the several wood-lengths, surface portions not formed in the course of performance of method step (i); and, (iv) performing method steps (a) to (d) of claim 1 on the said further pack thereby to produce in each of the wood- lengths thereof a second three-dimensional surface portion. The several wood lengths of said pack may be supported side-by-side lengthwise in contact with one another symmetrically about said certain pack longitudinal axis. Conveniently, said pack of wood lengths, before the performance of step (d) has a uniform rectangular preferably square cross-section. The method may be such that at least two of said surfaces share a common lengthwise-extensive boundary. The method may entail deriving each said template means from a two-dimensional pattern composed of a multiplicity of circular arcs some at least of which are contiguous at transition positions at which said arcs have a common tangent . The arcs of which said two-dimensional pattern is composed may be arcs struck from points contained in a figure in the form of a closed curve. The closed curve may be substantially in the form of a circle; it may be substantially in the form of an ellipse. The performance of the method on several lengths of which the pack is composed offers the possibility, as hereinafter further explained, of producing a multiplicity of artifacts each with at least one complex three-dimensional surface all such surfaces bearing the signature of the template profile involved in their generation. Artifacts so produced have, for this reason, a geometrical harmony. This, as remarked upon further hereinafter, is a matter of particular significance in the production of elements of which parts of furniture are constructed. Typically, the several artifacts referred to above might be arm members, legs and back portions, including the splat of a chair back, in, for example, the Chippendale style. According to the invention, also, an apparatus for performing the method as aforestated comprises: a base part ; first and second bearing parts supported with respect to said base part in axial alignment with one another; first and second pack-end support means supported for rotation in said first and second bearing parts, respectively, said support means being such as to enable a pack of wood lengths symmetrically disposed with respect to the longitudinal axis thereof to be clamped at its ends with said longitudinal axis coincident with said bearing part axis; first and second template support means respectively laterally disposed to either side of the first and second pack support structures and being adapted respectively to support first and second template members; and, soft-start drive means for rotatatively driving at least one of said pack-end support means with a rotational speed which accelerates from start-up to a predetermined working speed. Preferably, the apparatus may include means operable to vary the working speed of said drive means. The first and second bearing parts may be relatively movable in said axial direction. One said bearing part may be fixed with respect to said base part and the other axially movable along the base part towards and away from the first . The first and second pack support means may respectively comprise first and second face-plates. The soft-start drive means may include a motor having a rotor coupled to one only of the aforesaid support means, drive for the other support means relying upon transmission of power from said one support means to the other by way of the wood pack when, in use, the latter is in place between the two support means. Preferably, however, the apparatus incorporates means, independent of such pack, to ensure synchronous drive of said pack-end support means. The latter means may be constituted as a mechanical coupling linking a motor drive to one of said structures and the other said support structure. Such means may, for example, comprise a transmission which includes a lay-shaft disposed to the rear, say, of the apparatus, and first and second toothed belt and pulley arrangements coupled the one to said motor drive the other to said other support structure. A simpler and cheaper device, however, for ensuring such synchronous drive of the first and second pack-end support means comprises a an axially extensive power transmission shaft drivingly coupled to the two pack-end support means. Where a pack-end support means is axially displaceable with respect to the base of the apparatus, the shaft may extend through an aperture therethrough. There may be provided means integral with said base part, being means adapted to have attached thereto a tool, such, for example, as a saw, constrained for movement in planes perpendicular to said longitudinal axis at any position therealong and for translational movement sideways in the direction of the bearing axis and serving, also, to constrain said tool for movement in planes perpendicular to said bearing axis at any position therealong and being adapted, when first and second templates are respectively supported by said first and second template support means SUBSTITUTE SHEET (RULE 26 and when, in use of the lathe, with a pack of wood lengths rotating about its longitudinal axis coincident with said bearing axis, to create in the pack circumferentially extending slots or grooves. The production, using such means, in the length of wood of a multiplicity of relatively closely spaced, circumferentially-extensive grooves or slots facilitates the production of the finished article in that the wood outstanding from the level of the bottom of the slots or grooves, being weak in cross-grain, may be readily broken away from the remaining body of wood. Fruitless expenditure of time and effort arising from the removal from the pack of such surplus wood using an abrading file may thereby be avoided. The foregoing and other features of the method and apparatus (hereinaf er, for convenience, referred to as "the lathe") are hereinafter described with reference to the accompanying drawings in which: Fig.l is a simple diagrammatic representation of a side elevation of a lathe in accordance with the invention; Fig.2 is a plan view of the lathe of Fig.l; Figs.3 and 4 show opposite end views respectively of the lathe of Fig.l; Fig.5 is a side elevation corresponding to that of Fig.l but shown with one of two template members in place; Fig. 6 shows an end elevation of the lathe depicted in Fig.5; Fig. 7 shows a face-plate adapted for use with the clamp elements depicted in Figs.8a, 8b, 9a, and 9b hereof; Figs.8a and 8b are pictorial and plan views, respectively, of a first bracket member for use in association with the face-plate of Fig.7; Figs. a and 9b are corresponding pictorial and plan views, respectively, of a second bracket member for use with the face-plate of Fig.7; Fig.10a illustrates a geometrical method for generating a pattern from which may be devized template means defining a template profile particularly appropriate in the production of chair-backs and chair legs to the Queen Anne style; Figs.10b and 10c respectively illustrate forms for the profiles of template means in the production of a chair- leg and a portion of a chair-back, both profiles being devized using a pattern generated using the method of Fig.10a; Figs.11a to lie together illustrate a geometrical method of generating a pattern from which may be devized template means defining a template profile, such as that illustrated in Fig. lid, appropriate for producing chair-backs and chair- legs to styles frequently associated such furniture designers and manufacturers as Thomas Chippendale, during the period from about 1750 to about 1820 A.D. Figs.12a to 12c illustrate the use of a lathe in accordance with Figs.l to 9 in the production of chair-legs, particularly cabriole chair-legs of cross-section typical of the Queen Anne period; Figs.13a to 13c illustrate the use of said lathe in the production of cabriole chair legs to another style; Fig.14 together with Figs.15a and 15b, illustrate the use of the lathe in the production of chair legs, particularly cabriole chair-legs, of cross-section illustrated in Fig.15c; and, Figs.14 together with Figs.16a and 16b, illustrate the use of the lathe in the production of chair legs of cross-section illustrated in Fig.16c; Fig.17 is a diagrammatic cross-section of a pack of wood- lengths certain of which are to form chair legs, others to form chair arm portions yet others to form chair back portions, in particular splats, and some of which may serve no purpose other than as packing pieces; and, Fig.18 is a diagrammatic cross-section of different arrangement of wood-lengths in a pack of such lengths. Fig.19 is a pictorial representation of certain basic elements of a second lathe in accordance with the invention, being a lathe of more typical form than that illustrated in Figs. 1 to 7; Fig.20 is a diagram showing the face of each of the confronting face-plates of the lathe of Fig.19; Fig.21 is a diagram of one of two adaptor plates for attachment to the face-plates of Fig.18; Fig.22 is a diagram showing the adaptor plate of Fig.21 secured to the face-plate of Fig.20; Fig.23 is a pictorial representation of a lathe incorporating the features of the apparatus of Fig.19 and other elements essential or expedient to its operation in performing the method of the invention in arriving at the finished form for the artifact to be produced; Fig. 4 is a pictorial diagram corresponding to Fig.19 and showing two template members respectively supported with respect to the rotational axis of the lathe; Fig.25 is a pictorial diagram of the lathe of Fig.24 but with the wood-saw there depicted removed and a wood-abrading file for producing finished three-dimensional surfaces in wood lengths being turned on the lathe. The apparatus (Figs.l to 9b) comprises: a lathe having axially aligned first and second bearing parts 11a, lib, respectively, the first 11a, on which a lathe drive motor M is mounted, fixed with respect to the lathe bed 13, the second lib displaceable along fixed guide rods 15 towards and away from the first; first and second face-plates 17a, 17b, respectively, mounted for rotation in said first and second bearing parts 11a, lib, respectively, each formed with correspondingly distributed patterns 19 of radially- extensive receptacle portions 21, being in the example slots, associated with each face-plate 17a, 17b; a multiplicity of clamp means 23, 25, each adapted to be displaceably received within said face-plate receptacle portions 21 and to be fixed with respect to the face-plates 17a, 17b, at any position along said receptacle portions 21. The face-plates 17a, 17b, are synchronously driven throughout the full range of speeds at which it may be desired to operate the apparatus. To accommodate an extensive range of possible offset relationships between the axis of rotation of the lathe and the longitudinal axis of a work-piece to be formed to the desired shape, typically as hereinafter described, it may be necessary to utilise face-plates of up to, say, 15 inches in diameter . In the examples, the face-plate 17a is drivably coupled to the shaft of the motor M, and the face-plate 17b is drivably coupled to the face-plate 17a by means of a square cross-sectioned coupling shaft 26, the face-plates 17a, 17b being each broached with a square hole of appropriate size axially thereof adapted, respectively, to receive an end of the drive shaft 26 with a close though sliding fit. Other arrangements may, however, be employed so as to ensure that motion in the face-plate 17b follows that of the motor- driven face-plate 17a, faithfully. In particular, there may be a mechanical coupling (not shown) not including a shaft, such as shaft 26, linking the drive from motor M and the face-plate 17b. Such a coupling may, for example, comprise a transmission which includes a lay-shaft disposed to the rear, say, of the lathe, and first and second toothed belt and pulley arrangements coupled the one to said motor drive the other to said face-plate 17b. Clamp means, as 23, (Figs.8a and 8b) each have a plate portioπ 27, upstanding from one surface thereof, a right angle section piece 29, projecting from the other surface, an anti-rotation stud 31 and a threaded fastener arrangement 33 consisting, as with the clamp means of Figs.9a and 9b, of a captive threaded element 35 and nut 37. The other clamp means 25 each comprise a flat base portion 39 and, upstanding from an edge thereof, a flat flange portion 41. The lathe bed 13 has first and second laterally disposed longitudinally extensive slot arrangements, as 43a, 43b, respectively, and, slideable within each of said slot arrangements, first and second stand parts, as 45a, 5b, respectively, adapted respectively to support first and second elongate template members 47a, 47b, being laminar members with correspondingly formed desired profiles 49 along the upper edges thereof. In the lathe of Figs. 19 to 25, the first and second means for locating the pack-ends of a pack of wood-lengths each include an adaptor plate (Fig.21) having a outstanding formations, in the example, walls W forming the sides of a square. The adaptor plates (Fig.21) are adapted to be respectively secured to the end-plates (Fig.20) so as to produce an assembly as illustrated in Fig.22. Whilst the clamp means (Figs.8a to 9b) of the lathe depicted in Figs.l to 7, in operation clearly act directly on the pack-end portions of the pack L held thereby between the face-plates 17a, 17b, the outstanding walls of the adaptor plate P may, and in general will, require the introduction between such pack-ends and the outstanding walls W of the adaptor plate of shimming pieces (not shown) providing a tight fit between the pack-end portions and the walls W. In practice, the cross-sectional dimensions of the packs of wood-lengths to be subjected to turning in accordance with the method. In order to provide for this reqirement, a range of adaptor plates of the same form as that illustrated in Fig.21 but with outstanding wall formations of different sizes appropriate for the range of pack-end dimensions to be accommodated would be provided. In either event, the pack of wood lengths L is constituted from a multiplicity of separable wood pieces packed lengthwise side by side in contact with one another, the several wood pieces so packed having an axis of symmetry which is coincident with the rotational axis A A, and at least some of the pieces having their longitudinal axes parallel to but distinct from said rotational axis A A. Examples of such packing of the separable wood pieces are depicted in Figs. 17 and 18 to be more fully discussed hereinafter. As will be shown, the derivation of template profiles appropriate for the Queen Anne period may be based on the circle, whilst the derivation of gentler curved profiles appropriate for the later period mentioned may be based on the ellipse. The lathe bed 13 has first and second laterally disposed longitudinally-extensive slot arrangements, as 43a, 43b, respectively, and, slidable within each of said slot arrangements, first and second stand parts, as 45a, 45b, respectively, adapted respectively to support first and second elongate template members 47a, 47b, being laminar members with correspondingly formed desired profiles 49 along the upper edges thereof. The profile 49 of each of the template members 47a, 47b, may be of any desired form, including a straight edge form. It is illuminating to consider forms for profiles for the template members which are appropriate for the production of cabriole legs for chairs of the Queen Anne period in contrast to the forms for profiles for template members which are appropriate for the production of cabriole legs for chairs to distinctive forms arising during the period associated with, in particular, Thomas Chippendale. It is characteristic of cabriole legs for chairs of the Queen Anne period that they have very pronounced curvatures by comparison with cabriole legs favoured in furniture of the period extending from around 1750 and 1820. As will be shown, the derivation of template profiles appropriate for the Queen Anne period may be based on the circle, whilst the derivation of gentler curved profiles appropriate for the later period mentioned may be based on the ellipse. Referring, then, to Fig.10a, a pattern for a profile may readily be constructed employing a straight edge and compasses , only . In the figure: .D is a point (chosen to be the mid-point of the diameter segment OB) on the diametral line AB. A line is drawn from D through a point E and a point P 5 (again chosen as the mid-point of the line segment DE) selected. The pattern A (Fig.10b) is obtained as follows: From A draw arc OS; From D draw arc 0E; From P draw arc EQ; From R draw arc from S. Since the points A and D lie on the same line, the arcs OS and 0E are contiguous circular segments having a common tangent at the origin 0. Similarly, the points D P and E lying, as they do, on the same line, the arcs through 0E and EQ are contiguous circular segments with common tangent at E. Again, the point R, lying on the line AC, the arc from S and the arc OS are, as before, contiguous circular segments with common tangent at S. The curvilinear pattern form QEO and extending onwards through S is a pattern appropriate for template members for cabriole chair-legs of the Queen Anne period. By extending the arc through Q to D, a pattern (Fig.10c) appropriate for a chair back portion for a chair of the same period emerges. In the production of corresponding artifacts for chairs of the aforementioned later "Chippendale" period, patterns may be derived which rely on the geometry of the ellipse, the variation in different chord lengths and, in particular, the longer chord lengths available, offering, as will be ade clear, hereinafter, the possibility for production of more gentle curvilinear shapes in articles, cabriole chair- legs and back parts for chairs. Referring to Figs. 11a to lid, a pattern (Fig. lib) is generated from the end points A and B of a chord of an ellipse. From the pattern DCF, so produced, a further pattern may be derived using the construction of Fig. lie whereby the radii of the arcs are increased by the factor 2, the resultant pattern (Fig. lid) being substantially flatter than that of Fig. lib. Referring next to Figs 12a to 12c, procedures for the production of a set of four matching cabriole chair-legs to the Queen Anne style, are represented. Firstly, pairs of template members 47a, 47b, are devized to a pattern generated as described with reference to Figs.10a to 10c. The template members so devized are mounted in a lathe apparatus as hereinbefore described and a square-section straight length of wood 51 is supported off-axis between the face-plates 17a, 17b, by clamp members 23, packing pieces 53a, 53b, setting the amount of off-set in two orthogonal directions. With the face-plate 17a driven by the motor M, wood is removed from the wood-length 51, commencing at the edge 55, by movement of a file (not shown) in directions longitudinally of and radially towards said rotational axis A--A such that, with movement of the file in the aforesaid directions, material is removed from the periphery of the wood length as a result of contact between the file and the wood-length 51, the amount and distribution of wood material removed and the three-dimensional surface portion created in the wood length as a result of such wood removal being determined by limits set by the profile 49 of the template members 47a, 47b, and their positions relative to the wood- length. The profile 49 of the template members 47a, 47b, has a form such that the angle subtended at the axis A A by the surface 57 formed in the wood-length 51 varies along the wood-length with variation in the spacing between the file and the axis A A; it may be that the said spacing may be such along a segment (as at C) of the profile that the subtended angle constitutes a full circular arc. The process, just described, may be repeated with three further wood-lengths using the same packing pieces 53a, 53b, and the same template members 47a, 47b. The pack of four wood-lengths 51 each with a surface determined by the amount of off-set and the profile of the template members 47a, 47b, and their position, are next clamped, using the corner clamp members 53b, in the manner depicted in Fig. 12b and another pair of template members 47a, 7b, mounted in the lathe apparatus. The four wood-lengths 51 may be regarded as packing pieces, providing a certain axial off-set one for another, With the wood-lengths so supported, and with the motor- driven face-plate 47a rotating, wood is removed from, now, all four lengths using, as before, a file, so as to expose on each wood-length, a back surface 59 determined by the new template profile. The front and back surfaces 57, 59, share common lengthwise extensive boundary edges 61. The process described achieves not only a true form for a cabriole leg to the style of the Queen Anne period; it achieves this in the course of production of four identical such legs, an achievement not easily, readily and economically attained using hand-crafting methods. It will be readily apparent that the method of working is an efficient one . In the production of chair legs to the Queen Anne style, the degree of offset involved, i.e. the spacing between the lathe rotational axis and the longitudinal axis of each work-piece is relatively small. In such a circumstance, wood removed from a length of wood being, throughout the turning process, relatively close to the lathe rotational axis, the face-plates 17a, 17b, may be of relatively small diameter, and by implication, low inertia. In such circumstances synchronism in the motion of the face-plates 17a, 17b, may be effected by the agency of the work-piece or pieces, such, for example, the pack of four wood-lengths depicted. In any event, the close-packed arrangement (Fig.12b) of the work- pieces, the four lengths of wood 51, effectively excludes the possibility of employing a coupling shaft 26 (Fig.l) between the face-plates. In like manner, cabriole legs to the "Chippendale" style may be produced commencing with patterns as described with reference to Figs.11a to lid. Referring to Figs.13a to 13c, four wood-lengths 57 may be supported off-set with respect to the lathe axis A A in cross-formation about a central on-axis wood-length 62 of the same cross-sectional shape and dimensions as the wood-lengths to be shaped. The result of the overall process may be gathered from Figs.13a to 13c which show at Fig.13b the formation of a first surface 63, at Fig.13c the formation of a second surface 65 using the same template members 47a, 47b, and, in the same Fig.13c, a third surface 67, being one of four back surfaces formed, as with the surfaces 63 and 65, concurrently on the lathe. Once again, the method results in the production in a single operation of four complex and identical forms. Figs.14 and 15a to 15c and Figs.14 and Figs.16a to 16c, illustrate the process of concurrent formation of a set of four identical cabriole-legs, in the one case, to a cross-section represented at Fig.15c, and, in the other, to a cross-section represented in Fig.16c, the same two pairs of template members being employed for both cases, the one pair for the front surfaces 69 or 71, as the case may be, the other pair for back surfaces (not shown) for the legs. The greater off-sets between axes, arising from the geometry associated with forms associated with "Chippendale" - period chair legs, necessitate the employment of face-plates 17a, 17b, of diameter greater than those strictly called for in the production, as aforedescribed, of forms to the Queen Anne style. Whereas, in the latter case, no separate packing means is called for when turning the pack of four wood- lengths (Fig.12b), the concurrent production of four identical "Chippendale" style chair legs may be accomplished using centrally located packing means, as shown in Figs.13a to 13c . As previously intimated, whilst the process has been described with reference to the lathe of Figs. 1 to 9b in relation to the production of sets of four identical cabriole chair-legs of differing cross-section and lengthwise curvilinear shape, the process is applicable, equally to the generation of enantio orphic chair-back portions which, in the finished chair, are disposed symmetrically with respect to one another. As previously intimated, the power of the method resides in the ability to generate wooden artifacts which are of total harmony in style, each bearing the signature of the template means employed in their concurrent generation. Much of a complete article of furniture, and the more complex parts of the article of furniture at that, may be concurrently generated using the method and the lathe. Valuable examples of this may be gathered from Figs. 17 and 18. In each of the latter figures symbols are assigned to representa ions of the cross-sections of wood-lengths from which identical chair parts are to be produced all bearing the signature of the template means employed, the symbol L being associated with corresponding representations of wood-lengths from which identical chair-legs are to be generated, arm portions are to be formed, A with corresponding representations of wood-lengths from which identical chair-arm portions are. to be formed, B with corresponding representations of wood-lengths from which chair-back portions, namely splats, are to be produced, and Pp is associated with packing-pieces. The packing-pieces Pp may, of course, be recovered and used again if it is desired in the generaration of chair parts identical with the first set to be formed. Depending upon the case the so-called packing pieces may, being under the same template signature as all of the other pieces, be used in the construction of furniture. In the course of forming second and subsequent template- guided surfaces on several wood-lengths, the said wood- lengths being, of necessity, angularly displaced about their individual longitudinal axes, longitudinally-extensi e gaps are created in the stack. Further wood-lengths may be introduced into such gaps, such further lengths being thereafter turned to produce other furniture, e.g. chair, parts, such for example, as chair arm upstanding support members, again bearing the imprint of the template employed. Again, according to the furniture parts to be generated, it may be necessary, for purposes of symmetry, for example, to interchange and to rotate certain wood-lengths. An example may be found in Fig. 17 where, in the course of turning the pack there depicted, the arm-pieces Al must, following the forming of a first surface as indicated, be interchanged in position and, at the same time, rotated through 180. The arm-pieces A2 must be similarly handled. Notwithstanding the later introduction of further wood- lengths into gaps created in the pack in the course of turning, small voids and fissures inevitably will remain. It may be expedient to fill such fissures with a hard wax prior to further wood-removal. Using an abrading file in such removal, the wax will be worked into the furniture parts being generated. The lathe of Fig. 19 has (Fig.23), to either side of the face-plates 17a, 17b, stands 45a, 45b, and 45c adapted to receive, at their bifurcated free upper ends the first and second correspondingly profiled template members 47a, 47b, the stands being carried upstanding from carrier members C slideable with respect to the lathe bed 13. The lathe also has a guide rod R which is supported to extend longitudinally parallel to the rotational axis A A and pivotally connected to the guide rod R saw-carrier means M, being a frame structure adapted to receive a wood-saw S. The frame structure M is slideable along the rod and the pivotal movement of the frame M is such that a wood-saw S carried thereby is able to move towards the rotational axis A A only in a plane perpendicular thereto. The lathe of Fig.23 fitted with the two template members 47a, 47b, is shown in Fig. 24. In operation of the lathe, the pack of wood-lengths P is, as before, supported between end-plates 45a, 45b, the pack-end portions being now trapped within the outstanding walls W of the adaptor plates. With the pack rotating, circumferentially-extensive saw cuts may be formed in all wood-lengths thereof which offer a pack boundary surface, these being formed at intervals along the pack by action of the saw S under pivotal movement of the saw-carrier frame M about the guide rod R. Wood being weak in end-grain, the formation of slots or grooves by saw-cut action, enables bulk wood material to be readily broken away from the core material from which the finished artifact is to be created. The radially inwards movement of the saw 5 for this purpose must not, of course, intrude into the volume to be occupied by the finished artifact, and, to this end, means are provided limiting such inwards movement. In the example, the template carriers 45a to 45c are adjustable in height with respect to the carrier members C, being set at a first position, as illustrated in Fig. 24, for the purpose of surplus wood removal as mentioned and at a lower position illustrated in Fig. 25 for the purpose of removing wood to or approximating to the finished form for the article being created. This last-mentioned operation is, as represented in Fig.25, performed using a wood-abrading file F, being, preferably, a "half-round" file of the form described and claimed in Applicants co-pending UK Patent Application No. 9419555.9, that is to say a "half-round" file having a central abrading portion and at each side of the abrading portion, an end portion possessing SUBSTITUTE SHEET (RULE 26} substantially no abrasive power. In use, the file is moved in contact with the wood of the pack both longitudinally and radially with respect to the axis of rotation A A, wood being removed until such time as contact between the smooth end portions and the profiles of the two template members 47a, 47b, prevents further such abrasive wood-removal action, the non-abrasive character of the end-portions ensuring that template profiles suffer substantially no damage in the course of contact therewith by such end portions. In acordance with the method of the invention, the foregoing abrasive wood-removal action is to be repeated at least one further time, wood lengths being angularly displaced each time through a certain angle depending upon the finished form to be given the artifact being produced. This may, as with the production of chair legs to the Queen Anne style, involve (Figs.12a to 12c) the selection of part- formed artifacts from a multiplicity of packs P. The use of an abrading file provides the surfaces of the artifact being produced with a fine, smooth, even burnished finish. Nevertheless, it may be desirable to after the action of the file in producing the article sought, to further enhance the article using fine sand- papersand/or wire wool, and, to soften edges between contiguous surfaces formed on artifacts produced from a wood-length, scraper tools may be employed. Whilst, in the lathe apparatus described, the template means is constituted as a pair of structural template members, other template means might be employed. With the advent of numerically controlled milling machines, in particular, the template means might be in the nature of computer software operative to control suitable means, a rotating end-mill, perhaps, to move radially towards and longitudinally of the orbiting wood-lengths to effect removal of wood as described in achieving cross-sectional and longitudinal forms as depicted. The expression "template means" is therefore to be construed so as to embrace not only the use of one or more tangible profiled template members or computer software for the numerical control of the movement of a tool in the performance of the method, it is to include any other device (in the broadest sense of that word) capable of controlling or of constraining or of limiting the movement, to this end, of suitable means for the removal of material from the wood-length. It is within the scope of the invention to provide not only a method and an apparatus for producing complex three- dimensional forms made using such method and/or apparatus but also templates for mounting on the apparatus and patterns from which such templates may be fabricated. So, for examples , • patterns in paper, being patterns from which templates to a profile appropriate for use in the production of parts, cabriole chair-legs and chair-back members, for examples, using the method and apparatus in accordance with the present invention, all as hereinbefore described and discussed, in the faithful reproduction of a classic piece by, say, Chippendale.

Claims: C L A I M S 1. A method of producing, in wood, artifacts of complex three-dimensional form comprises: (a) devizing template means defining a profile appropriate for surfaces to be produced in the article; (b) supporting a pack of wood lengths side-by-side lengthwise in contact with one another about a certain pack longitudinal axis; (c) rotating said pack about said pack longitudinal axis; (d) moving wood removal means in directions longitudinally of and radially towards said longitudial axis such that wood is removed from each of the several wood lengths of the pack at the periphery thereof by the action of said wood removal means thereon, the amount and distribution of wood removed and the three-dimensional surfaces created in the several wood lengths of the pack as a result of such wood removal being determined by the profile of template means and its spatial relationship to said wood length. 2. The method claimed in claim 1 and which comprises: (e) displacing at least one of said wood lengths of the stack about its individual longitudinal axis, being distinct from said pack longitudinal axis, through a predetermined angle ; (f) repeating the method step (d) so as to create a second three dimensional surface in said at least one wood length; and , (g) for the creation of further three-dimensional surface portions (if any) in said wood lengths or any of them repeating method steps (c) to (e) in respect of each such surface . 3. A method of producing, in wood, artifacts of complex three-dimensional form which comprises: (i) performing method steps (a) to (d) specified in claim 1 successively on a multiplicity of packs of wood- lengths; (ii) selecting from each of said packs a particular wood- length ; (iii) supporting said selected wood-lengths to form a further pack with the several wood-lengths thereof angularly displaced through a certain angle with respect to one another about their longitudinal axes such as to expose, on the several wood-lengths, surface portions not formed in the course of performance of method step (i); and, (iv) performing method steps (a) to (d) of claim 1 on the said further pack thereby to produce in each of the wood- lengths thereof a second three-dimensional surface portion. 4. The method as claimed in claim 1, 2 or 3 in which the several wood lengths of said pack are supported side-by-side lengthwise in contact with one another symmetrically about said certain pack longitudinal axis. 5. The method as claimed in claim 1, 2 or 3 in which said pack of wood lengths has, before the performance of step (d), a uniform rectangular cross-section. 6. The method as claimed in any of claims 1 to 4 in which said pack has a uniform square cross-section. 7. The method as claimed in any of claims 1 to 6 which entails deriving each said template means from a two- dimensional pattern composed of a multiplicity of circular arcs some at least of which are contiguous at transition positions at which said arcs have a common tangent. 8. The method as claimed in claim 6 or 7 in which the said arcs of which said two-dimensional pattern is composed are arcs struck from points contained in a figure in the form of a closed curve. 9. The method as claimed in claim 8 in which the closed curve is substantially in the form of a circle. 10. The method as claimed in claim 8 in which the closed curve is substantially in the form of an ellipse. 11. The method as claimed in claim 9 substantially as described with reference to Figs.12a to 12c of the accompanying drawings. 12. The method as claimed in claim 10 substantially as before described with reference to Figs.13a to 13c of the accompanying drawings. 13. The method as claimed in claim 8 substantially as before described with reference to Figs. 14 and 15a to 15c or to Figs. 14 and 16a to 16c. 14. An apparatus for performing the method as aforestated which comprises: a base part ; first and second bearing parts supported with respect to said base part in axial alignment with one another; first and second pack-end support means supported for rotation in said first and second bearing parts, respectively, said support means being such as to enable a pack of lengths of wood to be clamped at its ends with the longitudial axis of said pack coincident with said bearing axis ; and, first and second means respectively laterally disposed to either side of the bearing axis, being first and second means adapted respectively to support first and second template members; and, soft-start drive means for rotatatively driving at least one of said pack-end support means with a rotational speed which accelerates from start-up to a predetermined working speed. 15. An apparatus as claimed in claim 14 in which said first and second pack-end support means comprise first and second face-plates, respectively, mounted for rotation as aforesaid and being each formed with correspondingly distributed patterns of radially-extensive receptacle portions;and associated with each face-plate a multiplicity of clamp means adapted to be displaceably received within said face¬ plate receptacle portions and to be fixed with respect to the face-plate at any position along said receptacle portions. 16. An apparatus as claimed in claim 14 in which said first and second pack-end support means respectively comprise first and second face-plates and first and second unitary adaptor means respectively secured to said first and second face-plates, said first and second adaptor means having first and second confronting correspondingly configured outstanding wall formations, respecti ely, each of which is such as to be capable of receiving a stack end portion and which, the first and second adaptor means being secured as aforesaid, enclose the rotational axis of the lathe and offer themselves outstanding towards one another from their respective adaptor means. 17. An apparatus as claimed in claim 14, 15 or 16 and which has means, not being the length of material which, in use, is between said pack-end support means, to ensure synchronous drive of said support means. 18. An apparatus as claimed in any of claims 14 to 17 which includes means operable to predetermine the working speed of said drive means. 19. An apparatus as claimed in any of claim 14 to 18 in which said first and second bearing parts are relatively movable in said axial direction. 20. An apparatus as claimed in claim 19 in which one said bearing part is fixed with respect to said base part and the other axially movable along the base part towards and away from the first. 21. An apparatus as claimed in any of claims 14 to 20 in which said soft-start drive means includes a motor having a rotor coupled to one only of the aforesaid support means, drive for the other support means relying upon transmission of power from said one support means to the other by way of the wood pack when, im use, the latter is in place between the two pack-end support means. 22. An apparatus as claimed in any of claims 14 to 20 which incorporates means effective, independently of a pack of wood lengths as may be present between said first and second pack-end support means, to ensure synchronous drive of said pack-end support means. 23. An apparatus as claimed in claim 22 in which said means is constituted as a mechanical coupling linking a motor drive to one of said structures and the other said support structure . 24. An apparatus as claimed in claim 23 in which said means comprises a transmission which includes a lay-shaft and first and second toothed belt and pulley arrangements coupled the one to said motor drive the other to said other support means. 25. An apparatus as claimed in claim 23 in which said means comprises an axially extensive power transmission shaft drivingly coupled to the two pack-end support means. 26. An apparatus as claimed in claim 25 in combination with claim 18 or 19 in which said axially extensive power transmission shaft is fixed with respect to one pack-end support means and extends through an aperture through the other . 27. An apparatus as claimed in any of claims 14 to 26 and which has means integral with said base part, being means adapted to have attached thereto a tool, such, for example, as a saw, constrained for movement in planes perpendicular to said longitudinal axis at any position therealong and for translational movement sideways in the direction of the bearing axis and serving, also, to constrain said tool for movement in planes perpendicular to said bearing axis at any position therealong and being adapted, when first and second templates are respectively supported by said first and second template support means and when, in use of the lathe, with a pack of wood lengths rotating about its longitudinal axis coincident with said bearing axis, to create in the pack circu ferentially extending slots or grooves. 28. An apparatus substantially as hereinbefore described with reference to Figs.l to 9b or with respect to Figs. 19 to 25 of the accompanying drawings. 29. A method of producing a template for an apparatus as claimed in any of claims 14 to 28 which comprises: marking a body of sheet material possessing or capable of being supported such as to exhibit a substantially stable geometric form, such, for examples, as laminated wooden sheet or metal sheet material, a linear pattern composed of boundaries of contiguous arc segments, the centres of curvature of adjacent arcuate segments being distinct and being contained in the same straight line; and removing material from said body such as to provide said sheet material with a profile corresponding to the shape of the pattern. 30. A method of producing a template for an apparatus as claimed in any of claims 14 to 28 which comprises: marking on a body of limp sheet material, such, for example, as paper, a linear pattern composed of a series of contiguous arcuate segments the centres of curvature of adjacent arcuate segments being distinct and being contained in the same straight line; attaching the limp sheet material so marked to a body of sheet material possessing or capable of being supported such as to exhibit a substantially stable form, such, for examples, as laminated wooden sheet material and metal sheet; and, removing material from said stable body of sheet material such as to provide from said stable body a template having a profile corresponding to the shape of the pattern marked on the limp sheet material. 31. A template produced by the method claimed in claim 29 or 30. 32. A pattern which comprises a body of limp sheet material marked with a linear pattern composed of a series of contiguous arcuate segments, the centres of curvature of adjacent arcuate segments being distinct and being contained in the same straight line. 33. A pattern member as claimed in claim 32, being a print. 34. An article manufactured in accordance with the method claimed in any of claims 1 to 13.

Inventors: MOORE ALAN ROBERT, MOORE, ALAN, ROBERT
Applicants: MOORE ALAN ROBERT, PAINTEXTRA LIMITED, MOORE, ALAN, ROBERT
Application year: 1995
Main classification: B23Q33
IPC codes: B23Q33, B23Q35, B27C7