FIELD OF THE INVENTION

This invention relates to a remote constant surface speed control and in particular, but not exclusively so, to a remote speed control for a wood turning lathe.

BACKGROUND TO THE INVENTION

The problem of varying surface speeds of the workpiece when working from a fairly large outer dimension to the centre thereof, and vice versa, has always been a problem when turning bowl type objects.

In the very earliest type of wood turning lathe where rotation of the lathe headstock was achieved by

reciprocating motion of a foot operated treadle converting reciprocating motion of the treadle into rotary motion by crank means, this problem of speed variation of the workpiece could be achieved to some degree although not in a constant varying action.

In later forms of wood turning lathes, the drive to the headstock is by belt from an overhead driven shaft and pulley to a number of pulleys of varying diameters at the headstock of the lathe. With this type of drive, it is necessary for the operator during a cutting process across a workpiece through varying diameters, to move the chisel away from the workpiece and change the belt to another pulley giving the required new speed and then start cutting operations again.

This problem also occurs with gear driven headstocks and although gear change levers may be available, it is not safely or physically possible to maintain a true cutting operation whilst trying to engage another drive gear with one hand whilst maintaining the cutting chisel on its support and in engagement with the workpiece. In effect, with gear driven and belt driven headstocks it is necessary to stop operations on the workpiece and then carry out the required gear change.

If, in order to overcome the necessity for changes in cutting speed, it is decided to chose an optimum speed for the chisel or cutting edge to move across the workpiece, this optimum speed being usually chosen that will be too fast at the rim of the workpiece and too slow at the centre. This action may partly satisfy the cutting speed requirements for particular diameters but usually results in flexing at the outer diameter of the workpiece with attendant vibration and ripple on the cut surface. Also, without the necessary surface speeds of the workpiece, it is detrimental to the finished correct presentation of the direction of grain in the finished workpiece article.

The present invention has been evolved to overcome the disadvantages of the prior constructions of wood turning lathes and allow an operator to incrementally alter workpiece speed as the cutting action proceeds without any significant interruption on the action of the operator, and with increased safety in the operation of the lathe.

SUMMARY OF THE INVENTION

The present invention provides in one aspec :-

a remote constant surface speed control mechanism for a wood turning lathe wherein variations in surface speed of a workpiece are controlled by electronic/electrical means accessible to the operator during cutting operations;

and in another aspect there is provided:-

a remote surface speed control for the headstock drive spindle of a wood turning lathe comprising manually operable electronic/electrical control means incorporated in the handle socket of a chisel or the like, hand controlled working tool, which socket locates a UHF transmitter adapted for finger control of the lathe headstock spindle speeds through a UHF received speed control potentiometer connected to the headstock spindle drive.

PREFERRED ASPECTS OF THE INVENTION

The electronic/electrical control means may comprise a UHF transmitter having hand or finger operating means and a receiver and control unit which operates a speed control potentiometer to control the headstock drive spindle speed via an electronic inverter drive system.

In order that the invention and its manner of performance may be more fully described, reference will now be made to

- A - embodiments of the invention as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWINGS

Figure 1 is a perspective view of part of a wood turning lathe;

Figure 2 is a perspective view of the use of a cutting chisel on the tool rest of the lathe;

Figure 3 is a perspective view of a control socket attachable on the chisel handle; and

Figure 4 is a perspective view of a bowl produced according to the present invention.

INTEGER LIST

5. Lathe

6. Lathe pedestal

7. Lathe pedestal

8. Lathe bed

9. Electric drive motor 10. Control box

11. Control button

12. Stop button

13. Start button

14. Chisel handgrip 15. Chisel handle

16. Control button

17. Control button

18. Workpiece

19. Chisel 20. Tool rest 21. Bowl

DETAILED DESCRIPTION WITH RESPECT TO THE DRAWINGS

Referring to the drawings, Figure 1 illustrates in part the lower section of a wood turning lathe 5 having pedestal members 6 and 7, the latter supporting the lathe bed 8, pedestal 6 also locating and supporting electric drive motor 9, headstock (not shown) and drive gear to the headstock spindle.

On pedestal 7 there is located a control box 10 housing a remote control UHF receiver (2 channel), manual/motorised speed control potentiometer, amplifier and relays for fast/slow control of the headstock spindle. The finger controlled rotary stepped button 11 controls the potentiometer and buttons 12 and 13 are stop/start buttons for the speed control. It will be noted that the remote speed control can be overridden by manual control if required.

Referring to Figure 2 there is illustrated the use of a plastics or diecast handgrip 14 which is fitted over a cutting chisel handle 15. Handgrip 14 houses a UHF (2 channel) transmitter with control buttons 16 and 17 for fast and slow operation of the headstock spindle. This control handgrip can be operated by the wood turner whilst cutting the workpiece 18 secured to the headstock with chisel 19 supported on tool rest 20.

Pressing the slow button on handgrip 14 continuously will cause a first signal of the UHF receiver to turn the potentiometer gradually to its slowest position and pressing the fast button will cause a second signal of the UHF receiver to turn the potentiometer gradually to its fastest position. Pressing the fast or slow button momentarily will cause infinite increases or decreases in speed as required through the complete speed range of the headstock drive spindle.

Figure 3 illustrates the removable handgrip 14 attachable over the chisel handle 15 and Figure 4 illustrates a finished bowl product 21 illustrating the necessity of correct rotational cutting speeds throughout the diameter of the bowl to bring out the end and side grain in the finished product.

The present invention, it will be appreciated, provides a means of controlling surface speed of a workpiece, wherein in the case of a bowl of 500mm outside diameter, it is necessary for optimum results to have available several speed changes during the cutting operation of the lathe.

The present invention allows the operator to change speed as necessary by merely pressing one of the buttons on handgrip 14 or on the control box 10 on pedestal 7 to either increase or decrease speed of the headstock spindle in infinite increments throughout the entire speed range of the lathe.

Thus, the operator has complete control of surface speed and cutting conditions without removing the cutting tool from the work surface or stopping the lathe. This allows for more efficient work practice, increased safety through absolute control and superior surface finish as optimum cutting speeds can be maintained across extreme diameter workpiece variations.

The present invention is eminently suitable for use with the lathe the subject of my Application No. PCT/AU96/00090.

It will be appreciated that the control mechanism of the present invention may be applied to large cranes controlled by D.C. motors which are expensive to maintain, also their control gear, by replacing with less expensive A.C. motors having a longer maintenance period and having a ground located operator to control level of the load being lifted, by radio which control gear would be relatively less

expensive to maintain.

It will also be appreciated that there may be made many modifications in details of design and configuration within the broad scope of the present invention and all such modifications are deemed to be within the scope of the present invention.