Woodturning Tool

Description

[0001] This invention relates generally to woodturning and, in particular, to a hand-held tool for use in the shaping of a timber workpiece into an article on a woodturning lathe. The tool is applicable in the woodturning of hollow-ware articles such as bowls, goblets, canisters and other containers, and it will be convenient to hereinafter describe the invention in relation to that exemplary application. It is to be appreciated, however, that the invention is not limited to that application and may be equally applicable to other articles, for example, spindle-ware such as furniture legs.

[0002] A large range of woodturning tools are available for shaping pieces of timber into hollow-ware articles. Those tools include cutting tools such as chisels and gouges as well as scraping tools such as scrapers, and are variously shaped to permit rapid rough cutting and scraping followed by more careful fine surface finishing of timber in order to form a smooth hollow-ware article quickly.

[0003] In using these tools a cutting edge is usually pushed into the timber fibres to force their severing and, particularly in end-grain hollowing of timber, that pushing occurs against or across the fibre grain. Whilst a fine surface finish can be achieved, it does require considerable expertise and concentration on the part of the toolturner in order to minimise ragged tearing of the timber fibre or more serious timber gouging. As such, fine finishing can be difficult to achieve and indeed articles can be severly damaged during that finishing, partioularly by inexperienced woodtur- ners.

[0004] In addition, existing cutting tools fine finish article hollows most effectively when a trailing corner of the tool cutting edge is very close to the timber surface being cut. Unless considerable care is exercised that trailing corner can contact the surface causing the cutting edge to dig into the timber. That can result in irreparable damage to the timber. Moreover, the tool can react violently causing it to be wrenched from the control of the woodturner with possible dangerous consequences.

[0005] U.S. patent 850,874 discloses a woodturner's tool having a handle with a bifurcated head, and a disk journalled between the head bifurcations. A series of cutting blades are fitted to the disk and project outwardly for individual presentation to a turning workpiece. The blades have different shaped cutting edges, at least one of which is shaped so as to be convexly arced about a periphery part at an end of the blade. This tool is not appropriate for woodturning hollow-ware articles.

[0006] U.S. patent 1,003,584 shows a lathe tool having a shank and a right angularly disposed head, that head having a cutting edge which is convexly curved along a section of the edge, This tool is not suitable for being hand-held while in use, but rather is intended to be mounted in a lathe for cutting exterior surfaces of turning workpieces. U.S. patent 795,688 concerns a lathe for turning hollow wooden ware and includes a machine held tool, although no details as to the tool construction are provided.

[0007] It is an object of the present invention to provide a relatively simple woodturning tool which may alleviate these disadvantages of these foregoing tools, It is another object of the present invention to provide a tool that permits fine surface finishing of surfaces of timber workpieces shaped on a woodturning lathe.

[0008] With the above objects in mind, the present invention provides a hand held cutting tool for use in cutting a turning timber workpiece, comprising an elongate tool shank and a cutting head at one end of the tool shank and rigid with the tool, the cutting head having a convexly arced sharp cutting edge extending in a flat plane along an arcuate periphery part of the cutting head, characterised in that a hole is formed solely within the cutting head and has an end opening, the hole providing an inner surface of the cutting head and the cutting head having an outer surface outwardly of and extending at least in part about the inner surface, the end opening of the hole having a periphery which is of oontinuous extent about the opening and which convexly arcs along at least a partial extent thereof between the inner and outer surfaces to thereby provide the arcuate periphery part along at least a section of which the sharp cutting edge extends, and in that the outer surface adjacent the periphery extends perpendicularly to the plane containing the cutting edge and the inner surface converges towards the outer surface to form the cutting edge, whereby, in use, the tool is hand held and presented to a turning timber workpiece so that the outer surface of the cutting head immediately adjacentthe periphery rubs on a surface of the workpiece and the cutting edge convexly arcs towards and engages the workpiece surface in a cutting action and the cutting head is thereafter moved over the workpiece surface with the cutting edge leading to progressively cut the workpiece.

[0009] Preferably the inner surface extends away from the cutting edge and the outer surface at an angle to an axis extending perpendicularly to the elongate tool shank, and the outer surface extends away from the cutting edge and the inner surface at an angle to the perpendicular axis.

[0010] Preferably, the cutting edge extends through an angle of at least about 180°. The end opening periphery of the hole may be circular in shape and in that case the cutting edge may extend entirely along the end opening periphery.

[0011] Preferably, the hole extends at least substantially perpendicularly to the elongate tool shank. The inner and outer surfaces adjacent the periphery may have an included angle up to about 15°.

[0012] Preferably, the hole extends entirelythrough the cutting head and has opposite end openings. Such a hole may facilitate removal of timber workpiece fibres from the cutting edge. That hole may pass through the cutting head at least substantially parallel to the elongate tool shank.

[0013] Although the tool may have only one cutting edge, where the hole is open-ended, another cutting edge may be provided on the cutting head. To that end, the other end opening of the hole has a periphery which is of continuous extent about that opening and which convexly arcs along at least a partial extent thereof between the inner and outer surfaces, and the cutting head has another arcuate sharp cutting edge extending in a flat plane along a substantial section of the arcuate periphery part of the other opening, the outer surface adjacent the periphery of the other opening extending perpendicularly to the plane containing the other cutting edge and the inner surface converging towards the outer surface adjacent the periphery of the other opening thereby to form the other sharp cutting edge. These two cutting edges may increase the versatility of the tool during use.

[0014] The following description refers to preferred embodiments of the woodturning tool of the present invention. To facilitate an understanding of the invention, reference is made in the description to the accompanying drawings where the tool is illustrated in those preferred embodiments. It is to be understood that the tool of the present invention is not limited to the preferred embodiments as hereinafter described and illustrated in the drawings.

[0015] In the drawings where like reference numerals identify like components:

Fig. 1 is a perspective view of a first preferred embodiment of the tool of the present invention;

Fig. 2 is a side view partly in section of the tool of Fig. 1;

Fig. 3 is a perspective view of a second preferred embodiment of the tool of the present invention; and

Fig. 4 is a side view partly in section of the tool of Fig. 3.

[0016] Referring initially to Figs, 1 and 2 of the drawings, there is generally illustrated woodturning tool 1. Tool 1, includes elongate tool shank 2, having spaced apart ends 3,4. In this embodiment, tool shank 2, is of a generally circular cross- sectional shape and extends generally along longitudinal axis 5.

[0017] During use tool 1, may be manually held by a woodturner by directly gripping shank 2. Alternatively, as in this embodiment, tool 1, is provided with separate handle 6, connected to end 3, of shank 2. That handle 6, is generally elongated and extends coaxially of tool shank 2.

[0018] Tool 1, also includes cutting head 7, at end 4, of tool shank 2. Conveniently, cutting head 7, is formed integral with shank 2, in order to improve the overall strength of tool 1.

[0019] As more clearly illustrated in Fig. 2, cutting head 7, is generally angled relative to longitudinal axis 5. Whilst that angle may vary considerably, an angle of about 15° has been found particularly suitable for some finishing applications of tool 1.

[0020] Cutting head 7, includes opposed cutting faces 8, and 9, which lie in planes extending parallel to or at least substantially parallel to longitudinal axis 5, depending upon the extent of angling of cutting head 7. Hole 10, extends through cutting head 7, so as to open onto cutting faces 8, 9. In this embodiment, hole 10, is of a circular shape although other shapes having curved sections, such as ovals and slots, may be equally applicable. This hole 10, provides with cutting faces 8, 9, opening peripheries 11, which are of a curved and continuous extent.

[0021] Hole 10, provides cutting head 7, with inner surface 12,- and head 7, also has outer surface 13, extending partway about inner surface 12, before merging into tool shank 2. Inner surface 12, and outer surface 13, converge toward each other so as to form cutting edge 14. That convergence is achieved by raking inner surface 12, from cutting face 11, about halfway toward cutting face 9. Although outer surface 13, is illustrated as extending generally parallel to the axial extent of hole 10, that surface may alternatively or additionally be raked to provide that convergence.

[0022] The included angle a, between converging surfaces 12, 13, may be any suitable angle which a woodturner using the tool finds suitable. In that regard, the angle may vary according to the height of the woodturner and the height of the woodturning lathe and in particular the tool rest of that lathe, bearing in mind that outer surface 13, is required to rub on the surface of timber being cut for proper cutting by tool 1. In this embodiment, that included angle is about 15°.

[0023] Tool 1, of this embodiment includes only one cutting edge 14, within cutting head 7. It should be appreciated, however, that at least one further cutting edge may be incorporated into tool 1, that cutting edge being provided on cutting face 9, by suitably converging inner surface 12, and/or outer surface 13. Where this occurs, the included angle between surfaces 12, and 13, forming this further cutting edge may be the same as or different from the included angle forming cutting edge 14, a different angle possibly increasing the versatility of tool I.

[0024] Tool 1, may be composed of any suitable material. In that regard, tool shank 2, and cutting head 7, may be composed of a tool metal such as high carbon steel, whilst handle 6, may be composed of timber or plastic.

[0025] In use tool 1, of this embodiment is presented to a surface defining a hollow of a turning timber workpiece (not illustrated) so that outer surface 13, rubs against that hollow surface. Tool 1, is then moved so that cutting edge 14, sweeps over that surface with cutting edge 14, leading and engaging the workpiece in a cutting action. Where the workpiece hollow is formed in timber end-grain, the sweep of cutting edge 14, will be generally outwardly along the hollow surface from the bottom to the opening of that hollow, whilst the sweep of cutting edge 14, is generally inwardly along the hollow surface formed in side- grain timber workpieces.

[0026] Referring now to Figs. 3 and 4 of the drawings, there is illustrated another embodiment of tool 1, in which shank 2, is of a generally square cross- sectional shape. It has been found that this particular shape may facilitate handling of tool 1. In particular, shank 2, can be rested flat against a tool rest of a woodturning lathe (not illustrated) so that cutting head 7, will be more easily orientated and retained in a correct position relative to a workpiece surface during a sweep of cutting edge 14, across that surface.

[0027] Tool 1, has cutting head 7, extending coaxially of shank 2, so that cutting faces 8, 9, extend generally parallel to each other and also longitudinal axis 5. In this embodiment, cutting head 7, has hole 10, extending therethrough and inner surface 12, and outer surface 13, shaped so that cutting edges 14, are provided on each of cutting faces 8, and 9. This is achieved by raking inner surface 12, inwardly from each cutting face 8, 9, halfway toward the other face.

[0028] Tool 1, of this other embodiment may be used in the same manner as in the previous embodiment, although of course, here the tool may be reversed for cutting timber workpiece with either cutting edge 14.

[0029] A woodturning tool according to the present invention has been found to improve severing of timber fibres when compared to previous tools and thus provide a smoother surface finish to that workpiece, particularly hollow-ware workpieces. Further, it has been found that the tool can be used in a wide variety of woodturning applications. To that extent, the tool is of a general purpose nature, unlike many previous tools which have a limited or specific application in woodturning.

[0030] Because of the curved nature of the tool cutting edge, there is minimum likelihood of that cutting edge inadvertently or accidentally digging into the turning timber workpiece being shaped. As such, damage to the workpiece may be minimal. In addition, that tool Is not likely to be dangerously wrenched from the control of a woodturner.

[0031] It is to be appreciated that modifications and/or alterations may be made to the tool without departing from the ambit of the present invention as defined in the claims appended hereto.

Claims

1. A hand held cutting tool for use in cutting a turning timber workpiece, comprising an elongate tool shank (2) and a cutting head (7) at one end (4) of the tool shank (2) and rigid with the tool (2), the cutting head (7) having a convexly arced sharp cutting edge (14) extending in a flat plane along an arcuate periphery part of the cutting head (7), characterised in that a hole (10) is formed solely within the cutting head and has an end opening, the hole (10) providing an inner surface (12) of the cutting head (7) and the cutting head (7) having an outer surface (13) outwardly of and extending at least in part about the inner surface (12), the end opening of the hole (10) having a periphery (11) which is of continuous extent about the opening and which convexly arcs along at least a partial extent thereof between the inner and outer surfaces (12, 13) to thereby provide the arcuate periphery part along at least a section of which the sharp cutting edge (14) extends, and in that the outer surface (13) adjacent the periphery (11) extends perpendicularly to the plane containing the cutting edge (14) and the inner surface (12) converges towards the outer surface (13) to form the cutting edge (14), whereby, in use, the tool is hand held and presented to a turning timber workpiece so that the outer surface of the cutting head (7) immediately adjacent the periphery (11) rubs on a surface of the workpiece and the cutting edge (14) convexly arcs towards and engages the workpiece surface in a cutting action and the cutting head (7) is thereafter moved over the workpiece surface with the cutting edge (14) leading to progressively cut the workpiece.

2. A tool as claimed in claim 1, characterised in that the inner surface (12) extends away from the cutting edge (14) and the outer surface (13) at an inclined angle to an axis extending perpendicularly to the elongate tool shank (2), and the outer surface (13) extends away from the cutting edge (14) and the inner surface (12) at an inclined angle to the perpendicular axis.

3. A tool as claimed in claim 1 or 2, characterised in that the cutting edge (14) extends through an angle of at least about 180°.

4. A tool as claimed in any preceding claim, characterised in that the end opening periphery (11) of the hole (10) is circular in shape.

5. A tool as claimed in any preceding claim, characterised in that the hole (10) extends at least substantially perpendicularly to the elongate tool shank (2).

6. A tool as claimed in any preceding claim, characterised in that the inner and outer surfaces (12, 13) adjacent the periphery (11) have an included angle of up to about 15°.

7. A tool as claimed in any preceding claim, characterised in that the hole (10) extends entirely through the cutting head (7) and has opposite end openings.

8. A tool as claimed in claim 7, characterised in that the other end opening of the hole (1) has a periphery which is of continuous extent about that opening and which convexly arcs along at least a partial extent thereof between the inner and outer surfaces (12, 13), and the cutting head (7) has another arcuate sharp cutting edge extending in a flat plane along a substantial section of the arcuate periphery part of the other opening, the other surface (13) adjacent the periphery of the other opening extending per- pedicularly to the plane containing the other cutting edge and the inner surface (12) converging towards the outer surface (13) adjacent the periphery of the other opening thereby to form the other sharp cutting edge.

Ansprüche

1. Handwerkzeug zur Verwendung beim Schnitzen eines-Drehholzwerkstückes, mit einem länglichen Werkzeugschaft (2) und einem Schneidekopf (7) an einem Ende (4) des Werkzeugschaftes (2) und starr damit verbunden, wobei der Sahneidekopf (7) eine konvex gebogene scharfe Schneidekante (14) hat, welche sich in einer flachen Ebene entlang eines gekrümmten Umfangteiles des Schneidekopfes (7) erstreckt, dadurch gekennzeichnet, dass ein Loch (10) nur innerhalb des Schneidekopfes ausgebildet ist und eine Endöffnung hat, wobei das Loch (10) eine Innenfläche (12) des Schneidekopfes (7) bildet und der Schneidekopf (7) eine Aussenfläche (13) hat, die sich ausserhalb der Innenfläche (12) befindet und sich wenigstens zum Teil um die Innenfläche (12) erstreckt, wobei die Endöffnung des Loches (10) einen Umfang (11) hat, welcher sich kontinuierlich um die Öffnung herum und mindestens entlang eines Teiles davon zwischen den Innen und Aussenflächen (12, 13) in einem konvexen Bogen erstreckt, um dadurch den gekrümmten Umfangsteil bereitzustellen, innerhalb dessen sich die scharfe Schneidekante (14) mindestes entlang eines Bereiches davon erstreckt, und dadurch, dass die Aussenfläche (13) sich neben dem Umfang (11) senkrecht zu der die Schneidekante (15) enthaltende Ebene erstreckt und die Innenfläche (12) in Richtung der Aussenfläche (13) konvergiert, um die Schneidekante (14) zu bilden, wodurch bei Verwendung des Werkzeugs, dieses mit der Hand gehalten und einem drehenden Holzwerkzeug hingehdalten wird, so dass die Aussenfläche des Schneideskopfes (7) direkt neben dem Umfang (11) auf einer Fläche des Werkstückes reibt und die Schneidekante (14) einen konvexen Bogen zur Werkstückoberfläche spannt und diese beim Schneiden berührt und der Schneidekopf (7) danach mit der Schneidekante (14) über die Werkstückoberfläche geführt wird, wodurch das Werkstück progressiv geschnitzt wird.

2. Werkstück nach Anspruch 1, dadurch gekennzeichnet, dass die Innenfläche (12) sich von der Schneidekante (14) und der Aussenfläche (13) unter einem eingeschlossenen Winkel zu einer Achse weg erstreckt, die senkrecht zum länglichen Werkzeugschaft (2) steht, und die Aussenfläche (13) sich von der Schneidekante (14) und der Innenfläche (12) unter einem eingeschlossenen Winkel zu der senkrechten Achse erstreckt.

3. Werkzeug nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Schneidekante (14) sich über einem Winkel von mindestens 180° erstreckt.

4. Werkzeug nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass der Unmfang (11) der Endöffnung des Loches (10) kreisförmig ist.

5. Werkzeug nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass das Loch (10) sich mindestens im wesentlichen senkrecht zum länglichen Werkzeugschaft (2) erstreckt.

6. Werkzeug nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die Innen- und Aussenflächen (12, 13) neben dem Umfang (11) einen Winkel von etwa 15° einschliessen.

7. Werkzeug nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass das Loch (10) sich ganz durch den Schneidekopf (7) hindurch erstreckt und sich gegenüberliegende Endöffnungen hat.

8. Werkzeug nach Anspruch 7, dadurch gekennzeichnet, dass die andere Endöffnung-des Loches (10) einen Umfang hat, -der sich kontinuierlich um die Öffnung erstreckt und einen konvexen Bogen entlang mindestens eines Teiles davon zwischen den Innen und Aussenflächen (12,13) schlägt und der Schneidekopf (7) eine weitere gebogene scharfe Schneidekante hat, welche sich in einer flachen Ebene entlang eines wesentlichen Bereiches des gekrümmten Unnfangteiles der anderen Öffnung erstreckt, wobei die Aussenfläche (13) neben dem Umfang der anderen Öffnung sich senkrecht zu der die andere Schneidekante enthaltenden Ebene erstreckt und die Innenfläche (12) zur Aussenfläche (13) neben dem Umfang der anderen Öffnung konvergiert, um so die andere scharfe Schneidekante zu bilden.

Revendications

1. Outil à découper à la main destiné à être utilisé dans le tournage d'une pièce à travailler en bois tournante, comprenant une tige (2) allongée et une tête de découpage (7) à une extrémité (4) de la tige (2) et rigide avec la tige (2), la tête de découpage (7) ayant une arête de coupe (14) aiguë arquée de façon convexe s'étendant dans un plan plat le long d'une partie périphérique arquée de la tête de découpage (7), caractérisé en ce qu'un trou (10) est formé uniquement dans la tête de découpage et a une ouverture en bout, le trou (10) fournissant une surface intérieure (12) de la tête de découpage (7) et la tête de découpage (7) ayant une surface extérieure (13) à l'extérieur de et s'étendant au moins en partie autour de la surface intérieure (12), l'ouverture en bout du trou (10) ayant une périphérie (11) qui s'étend de façon continue autour de l'ouverture et qui est arquée de façon convexe le long d'au moins une partie de son étendue entre les surfaces intérieure et extérieur (12, 13) pour fournir ainsi la partie périphérique arquée le long d'au moins une zone le long de laquelle s'étend l'arête de coupe tranchante (14), et en ce que la surface extérieure (13) adjacent à la périphérie (11) s'étend perpendiculairement au plan contenant l'arête de coupe (14) et la surface intérieure (12) converge vers la surface extérieure (13) pour former l'arête de coupe (14), de sorte que si pendant l'usage l'outil est tenu par la main et présenté à une pièce à travailler en bois tournante de sorte que la surface extérieure de la tête de coupe (7) immédiatement adjacent à la périphérie (11) frotte sur une surface de la pièce à travailler et l'arête de coupe (14) forme un arc convexe vers la surface de la pièce à travailler et contacte celle-ci pendant le découpage et la tête de coupe (7) est déplacée ensuite le long de la surface de la pièce à travailler avec l'arête de coupe (14) causant le découpage progressif de la pièce à travailler.

2. Outil selon la revendication 1, caractérisé en ce que la surface intérieure (12) s'étend à partir de l'arête de coupe (14) et de la surface extérieure (13) sous un angle incliné vers un axe s'étendant perpendiculairement à la tige allongée (2), et la surface extérieure (13) s'étend à partir de l'arête de coupe (14) et de la surface intérieure (12) sous un angle incliné vers l'axe perpendilaire.

3. Outil selon la revendication 1 ou 2, caractérisé en ce que l'arête de coupe (14) s'étend sur un angle d'au moins environ 180°.

4. Outil selon l'une quelconque des revendications précédentes, caractérisé en ce que la périphérie (11) de l'ouverture en bout du trou (14) est de forme circulaire.

5. Outil selon l'une quelconque des revendications précédentes, caractérisé en ce que le trou (10) s'étend au moins substantiellement perpendiculairement à la tige allongée (2).

6. Outil selon l'une quelconque des revendications précédentes, caractérisé en ce que les surfaces intérieure et extérieure (12, 13) forment un angle jusqu'à environ 15° adjacent à la périphérie (11

7. Outil selon l'une quelconque des revendications précédentes, caractérisé en ce que le trou (10) s'étend entièrement à travers la tête de coupe (7) et a des ouverture opposées en bout.

8. Outil selon la revendication 7, caractérisé en ce que l'autre ouverture en bout du trou (10) a une périphérie qui s'étend de façon continue autour de l'ouverture et qui forme un arc convexe le long au moins une partie de celle-ci entre les surfaces intérieure et extérieure (12, 13) et que la tête de coupe (7) a une autre arête de coupe tranchante arquée s'étendant dans un plan plat le long d'une section substantielle de la partie périphérique arquée de l'autre ouverture, la surface extérieure (13) adjacent à la périphérie de l'autre ouverture s'étendant perpendiculairement au plan contenant l'autre arête de coupe et la surface intérieure (12) convergeant vers la surface extérieure (13) adjacent à la périphérie de l'ouverture pour former ainsi l'autre arête de coupe tranchante.

Drawing