OUTBOARD TURNING METHOD, TOOLREST SUPPORT, AND TOOLREST

Abstract: Method of outboard turning of an article (4) on a lathe (1), a cantilever toolrest support (10), and a toolrest (13). The toolrest support (13) is preferably planar and is positioned under the bed (6) of the lathe (1) below the headstock (2). A levelling plate (6) is positioned under the tailstock end (3) of the bed (8). Alternatively, the support (13) can extend along the length of the bed (8). The toolrest (13) has a tool supporting bevel (24) extending along an upper edge of the toolrest (13) and an article clearing bevel (24) extending along the opposite lower edge of the toolrest (13). Using the above and an adjustable toolrest holder (10) mounted on the cantilever toolrest support (13), an article (4) such as a bowl (4) can be outboard turned with the angle (14) between the tool and the vertical maintained approximately equal to the usual tool sharpening angle. Also the horizontal distance between the article (4) and the region at which the tool (14) is supported is maintained at a minimum.

Description: OUTBOARD TURNING METHOD, TOOLREST SUPPORT, AND TOOLREST The present invention relates to a method of outboard turning of an article on a lathe, a cantilever toolrest support, and a toolrest. BACKGROUND ART The turning of articles on lathes is well known and such lathes have a headstock and a tailstock located at either end of the lathe bed which extends between the headstock and the tailstock. Long articles to be turned extend between the 0 headstock and the tailstock. However, where a large article is to be turned, such as a bowl having a large diameter, then this article can be supported by the headstock only. To prevent the bowl striking the bed, the bowl is supported from the end of the headstock opposite the tailstock. This known 15 procedure is termed "outboard turning". During normal turning, the cutting tool is supported by a toolrest which is in turn supported in a toolrest holder mounted on the bed of the lathe. For outboard turning it is not possible to use this toolrest holder. Hitherto a 20 freestanding stand or support has been positioned adjacent the headstock and a toolrest holder is positioned on the support. Since the support must be moveable in order to provide a gross adjustment of the position of the toolrest holder, this support is often not very stable and thus some vibration of 25. the toolrest during use results. This vibration and the generally awkward nature of the arrangement are generally unsatisfactory. In addition, conventional toolrests present some difficulties in turning an object such as a bowl since it is 30 not always possible to locate a portion of the toolrest closely adjacent the curved portion of the article to be turned. Thus, although the tool is able to be supported by the toolrest, the region of contact between the tool and the toolrest is spaced some distance from the cutting edge of the 35 tool and thus there is a tendency for the tool to flex. In addition, it is difficult to maintain the tool at the correct cutting angle while keeping the horizontal distance between the article being turned and the region of contact between the tool and toolrest to a minimum. i - 2 - OBJECT OF THE INVENTION The objects of the present invention are to provide a method of outboard turning, a cantilever toolrest support, and a toolrest which will substantially overcome, or ameliorate, the above mentioned disadvantages. DISCLOSURE OF THE INVENTION According to a first aspect of the present invention there is disclosed a method of outboard turning of an article on a lathe having a headstock, a tailstock and a bed with said article being mounted on said headstock facing away from said tailstock, characterised in that a cantilever toolrest support is positioned under said bed below said headstock and extends away from said bed, a toolrest holder is mounted on said support and is adjustable between a plurality of locations on said support, and a toolrest is held in said toolrest holder, said toolrest having oppositely located tool supporting and article clearing bevels. According to a second aspect of the present invention there is disclosed a toolrest for use with the above described method, the toolrest having oppositely located tool supporting and article clearing bevels. According to a third aspect of the present invention there is disclosed a cantilever toolrest support for use in the above described outboard turning method, the support being substantially planar and being adapted to be positioned under the bed of the lathe at its headstock end, with the support extending away from the headstock. BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of the present invention will now be described with reference to the drawings in which Fig 1 is a front elevation of a substantially conventional lathe having an outboard turning support plate upon which a toolrest holder is mounted and which in turn supports a toolrest, Fig 2 is a cross-sectional view along the line I-I of Fig 1, Fig 3 is a plan view of three toolrest supports each in accordance with the present invention. Fig 4 is a perspective view of.one of the toolrests of Fig 3, and Fig 5 is a vertical cross-section through a bowl being turned in accordance with the method of the preferred embodiment, and BEST MODE OF CARRYING OUT THE INVENTION As best seen in Fig 1, the preferred embodiment of the present invention is put into practice with a substantially conventional lathe 1 having a headstock 2 and a tailstock 3. Mounted for outboard turning on the headstock 2 is a wooden bowl 4. The lathe 1 is normally supported by a bench or legs 5, however, a planar outboard turning support plate 6 and a levelling plate 7 are positioned between the lathe 1 and legs 5 at the headstock and tailstock ends of the bed 8 of the lathe respectively. This is easily accomplished by passing the bolts which connect the legs 5 to the bed 8 through appropriately positioned holes located in the support plate 6 and levelling plate 7. As best seen in Figs 1 and.2, an outboard toolrest holder 10 is releasably secured to the support plate 6 by means of a fastener 11. A slot 12 (Fig 2) in the holder 10 permits the position of the holder 10 on the support plate 6 to be adjusted. The holder 10 carries a toolrest 13 which supports a cutting tool 14 with which the bowl 4 is turned. As indicated by broken lines in Fig 1, the support plate 6 and levelling plate 7 can be combined into a single plate which extends along the length of the bed 8. In addition, if desired, a prop or strut 15 can be provided at the free end of the support plate 6 to provide additional rigidity for the holder 10. The preferred form of toolrest 13 is best illustrated in Figs 3 to 6. As seen in Figs 3 and 4, the toolrest 13 preferably has a substantially S-shape when viewed in plan, the degree of curvature of the toolrest 13 selected for a particular job, or a particular part of a job, depending upon the curvature of the article to be turned. As best seen in Fig 5, the toolrest 13 is provided with a modified rectangular cross-section. The toolrest 13 has an upper surface 20, a lower surface 21„ a front surface 22 and a rear surface 23. Extending along the length of the toolest 13 and also extending between the upper surface 20 and front surface 22 is a first bevel 24 which supports the tool 14. The angle between the bevel 24 and the vertical is preferably approximately 25° which is approximately less than or equal to the usual sharpening angle of the tool 14. The width of the upper surface 20 is preferably approximately 2mm. Also extending along the length of the toolrest 13, but extending between the lower surface 21 and the rear surface 23 is a second bevel 25 which is substantially opposite to the first bevel 24. It will be apparent to those skilled in the art, that the first bevel 24 supports the cutting tool 14 at an inclined angle which is to be preferred in turning wooden articles. In addition, the second, article clearing, bevel 25 enables the toolrest 13 to be located very close to the bowl 4. In this way, the distance between the cutting tip or edge 27 of the tool 14 can be maintained at a short spacing from the region in which the tool 14 is supported by the toolrest 13. This ■> tends to restrict any -flexure of the tool 14 to a minimum. In addition, the horizontal distance 30 between the bowl 4 and the region on the toolrest 13 which supports the tool 14, is also kept to a minimum. This results in better control of the tool 14. INDUSTRIAL APPLICABILITY The above described embodiments of the present invention are applicable to the outboard turning of articles, especially of large diameter. Thus the present invention finds particular use in the turning of wooden bowls. However, the invention is not restricted to wooden articles since the present invention is also of use in the finishing of spun metal articles. The forgoing describes only some embodiments of the present invention and modifications, obvious to those skilled in the art, can be made thereto without departing from the scope of the present invention.

Claims: CLAIMS 1. A method of outboard turning of an article on a lathe having a headstock, a tailstock and a bed with said article being mounted on said headstock facing away from said tailstock, characterised in that a cantilever toolrest support is positioned under said bed below said headstock and extends away from said bed, a toolrest holder is mounted on said support and is adjustable between a plurality of locations on said support, and a toolrest is held in said toolrest holder, said toolrest having oppositely located tool supporting and article clearing bevels. 2. A method as claimed in claim 1 wherein said toolrest has a substantially rectangular cross-sectional shape modified by said tool supporting bevel extending along said toolrest between the upper surface thereof and a front face thereof and by said article clearing bevel extending along said toolrest between the lower surface thereof and the rear face thereof. 3. A method as claimed in any one of claim 1 or 2 wherein said toolrest support is substantially planar and extends under the bed of said lathe. 4. A method as claimed in claim 1 or 2 wherein said toolrest support is substantially planar and of substantially equal thickness to a levelling plate located under the tailstock end of said bed. 5. A toolrest for use in the method of claim 1 and having oppositely located tool supporting and article clearing bevels. 6. A toolrest as claimed in claim 5 wherein said toolrest has a substantially rectangular cross-sectional shape modified by said tool supporting bevel extending along said toolrest between an upper surface thereof and a front face thereof and by said article clearing bevel extending along said toolrest between a lower surface thereof and a rear face thereof. 7. A cantilever toolrest support for use in the outboard turning method of claim 1 on a lathe having a headstock, a tailstock and a bed, said support being generally said support extending away from said headstock. 8. A support as claimed in claim 7 and shaped to extend the length of said bed. 9. A support as claimed in claim 7 and adapted to co-operate with a levelling plate located under said bed beneath said tailstock, said support having a thickness substantially equal to that of said levelling plate.

Inventors: DARLOW MICHAEL JOHN, DARLOW, MICHAEL, JOHN
Applicants: DARLOW MICHAEL JOHN, DARLOW, MICHAEL, JOHN
Application year: 1986
Main classification: B27C7
IPC codes: B27C7