Ornamental turning device

An ornamental turning device (10) comprises a shaft (11) on which is mounted a work to be decorated. The device (10) also comprises tool drive means (5) for driving a tool (7) for decorating the work (9). The driving mechanism (5) ensures that the reciprocating blade of tool (7) reciprocates at a rate proportional to the rate of rotation of the shaft (11).

This invention relates to an ornamental turning device and to a tool drive 
mechanism and a tool for such an ornamental turning device. 
An ornamental turning device of this type may be used to engrave a pattern 
in an object, for example a wooden goblet, which has been worked upon a 
lathe. 
It is known to engrave a pattern on an object such as a goblet by hand. For 
a pattern which repeats itself around the circumference or perimeter of 
the object, it is necessary to make accurate measurements of the 
circumference of the object and then to mark the surface of the object at 
the precise points at which it will be necessary to make cuts in the 
object. Such a process is time consuming and requires a high level of 
skill. 
According to a first aspect of the invention: there is provided an 
ornamental turning device comprising: 
a rotatable shaft adapted to receive a chuck at a first end; 
a tool for engraving an object attachable to the chuck, and comprising a 
reciprocating blade; and 
tool drive means driveably connectable to the shaft for driving the tool, 
whereby in use, the rate at which the blade reciprocates is proportional 
to the rotational speed of the shaft. 
By means of the device according to the invention, an object which has been 
worked on a lathe, may be engraved whilst still in place on the lathe. 
By linking the rate of reciprocation of the blade of the tool with the 
rotational speed of the shaft on which the object to be engraved is 
mounted by means of the chuck, the spacing of cuts formed by the tool is 
linked to the circumferential measurement of the object. This ensures that 
grooves are regularly spaced around the circumference. 
Preferably, the device further comprises a tool rest which ensures that the 
position of the tool in a plane at right angles to the axis of rotation of 
the shaft remains substantially constant. The shaft may be orientated at 
any convenient position, but generally it will have a horizontal axis of 
rotation. The tool rest may then comprise a substantially horizontal 
surface on which the tool may rest. The horizontal movement of the tool 
may then be dictated by the operator, whilst the vertical position of the 
tool remains substantially constant. 
Advantageously, the tool should approach the work piece radially to its 
axis of rotation. The tool rest should therefore be tiltable in two 
directions in order that diamonds or "lattice work" grooves be produced. 
Alternatively, the tool may be held on the tool rest by mechanical means, 
which mechanical means determine the horizontal movement of the tool. 
The extent of horizontal movement of the tool will determine the length of 
the cut produced in the object by the tool. 
Preferably, the device comprises a driving cog connectable to the shaft, 
and the tool drive means comprises: 
a driven cog driveably connectable to the driving cog; 
at least one cam rotatable with the driven cog, which cam comprises at 
least one lobe; 
a cam follower adapted to follow the surface of the at least one cam; and 
means for connecting the tool to the cam follower, whereby reciprocation of 
the blade is determined by the movement of the cam follower over the cam 
surface. 
According to a second aspect of the invention there is provided a tool 
drive means comprising: 
a driven cog; 
at least one cam rotatable with the driven cog, which cam comprises at 
least one lobe; 
a moveable cam follower which follows the surface of the at least one cam: 
and 
means for connecting a tool to the cam follower, whereby reciprocation of a 
blade of the tool is determined by movement of the cam follower. 
Preferably, the driving cog is positioned on the shaft on which the object 
to be worked is positioned. In alternative arrangements however, the 
driving cog may be positioned on a separate shaft and connected to the 
shaft. 
Preferably, the driving and driven cogs are connected to one another by 
means of a drive belt, chain, or intermediate cog, etc. 
The at least one lobe comprises a concave surface in the surface of the 
cam. The presence of the lobe therefore causes the cam follower to move 
radially towards the centre of the cog. This radial movement of the cam 
follower causes a reciprocating movement of the blade of the tool. 
The ratio of the number of teeth on the driving cog to the number of teeth 
on the driven cog, in conjunction with the number, size and position of 
the lobes on the cam, governs the number, depth and length of cuts around 
the circumference of the object, in a given pattern. 
The tool may be connected to the cam follower by any convenient means, for 
example hydraulic or pneumatic links. Preferably however, the tool is 
connected by means of a flexible cable. 
Preferably, the cam follower comprises a pivoted elongate member having a 
ball race at one end, for following the surface of the cam, and is pivoted 
at an opposite end. The flexible cable may then be connected to the 
elongate member. Thus, when the ball race of the cam follower follows the 
surface of a lobe, the ball race will move towards the centre of the cog. 
This causes the elongate member to pivot about the pivot point, and causes 
the cable to release the blade outwardly under action of spring in tool. 
The cam follower may be pivoted on a shaft to allow for selection of the 
cam by moving the follower laterally. 
Advantageously, the tool comprises; a housing having a front open end and a 
back open end: a cutting blade moveably positionable within the housing 
and having a cutting position in which the blade protrudes through the 
front open end of the housing, and a non-cutting position in which the 
blade has retracted some distance within the housing; means for connecting 
the tool to the drive means; and biasing means for biasing the tool in the 
cutting position. 
According to a third aspect of the invention there is provided a cutting 
tool comprising: a housing having a front open end and a back open end; a 
cutting blade moveably positionable within the housing and having a 
cutting position in which the blade protrudes through the first end of the 
housing and a non-cutting position in which the blade has retracted some 
distance within the housing; means for connecting the tool to the drive 
means; and biasing means fop biasing the tool in the cutting position. 
In use as the cam follower follows the surface of the rotating cam, the 
cutting tool will be biased to the cutting position wherein a first end of 
the cutting blade protrudes through the first end of the housing when the 
follower meets a lobe on the cam. The biasing means causes the blade to 
remain in this position. When the cam follower tracks the non-lobe surface 
of the cam, the elongate member of the cam follower will cause the cable 
to pull the cutting blade into the non-cutting position in which the blade 
does not touch the work. The biasing means will ensure that the blade 
returns to the cutting position at the next lobe. 
Advantageously, the position of the cable relative to the ball race and 
pivot end of the elongate member of the cam follower is variable. This 
enables the sensitivity of the device to be varied. For example, the 
nearer the cable is attached to the pivot point of the elongate member, 
the smaller will be the distance travelled by the cable end. Equally, the 
nearer the cable end is attached to the ball race, the further will be the 
distance travelled by the cable end when the ball race tracks into a lobe 
on the cam. 
Preferably, the driving means comprises a plurality of cams. Each cam may 
have a different arrangement of lobes. For example, the lobes on one cam 
may be offset relative to the lobes on a neighbouring cam. The number 
and/or shape of the lobes may also vary from cam to cam. The different 
arrangements of lobes on each cam allows the spacing and/or shape of the 
cuts to be varied, and thus allows the more intricate pattern of engraving 
to be developed. 
Embodiments of the invention will now be described by way of example only 
with reference to the accompanying drawings in which: 
FIG. 1 is a schematic representation of an ornamental turning device 
according to the first aspect of the invention including tool drive means 
according to the second aspect of the invention and a tool according to 
the third aspect of the invention: 
FIG. 2 is a schematic diagram of the driven cog and cam arrangement of the 
drive means of FIG. 1; 
FIG. 3 is a cross-sectional representation of the arrangement of FIG. 2; 
FIG. 4 is a schematic diagram of the tool shown in FIG. 1; and 
FIG. 5 is a schematic diagram of a second embodiment of the invention.

Referring to FIG. 1, an ornamental turning device according to the first 
aspect of the invention is designated generally by the reference numeral 
10. The device 10 comprises a shaft 11 which forms part of a lathe 1. 
Mounted on one end of the shaft 11 is a standard chuck 2 for holding the 
work 9 to be decorated. In this example, the work 9 comprises a wooden 
goblet. The device 10 further comprises tool drive means 5 comprising a 
tool drive mechanism, for driving a tool 7 which in this example is 
designed to be hand held. 
The tool 7 comprises a reciprocating blade which is controlled by a 
flexible cable 6. The drive mechanism 5 ensures that the blade of the tool 
7 reciprocates at a rate proportional to the rate of rotation of the shaft 
11 in a manner to be described herein. Around the shaft 11 is positioned a 
driving cog 3 which in this example comprises 44 teeth. The drive 
mechanism 5 comprises a driven cog 12 which in this example comprises 20 
teeth. The two cogs 3, 12 are drivingly connected to one another by means 
of a drive belt 4. The driven cog 12 causes a cam arrangement 35 (FIG. 2) 
to rotate. 
Referring now to FIGS. 2 and 3, the tool drive mechanism will be described 
in more detail. The driven cog 12 causes a cam arrangement 35 to rotate 
with the driven cog 12 about cam shaft 26. The cam arrangement 35 may 
comprise one or more cams, and in this example it comprises three cams. 
Each cam comprises one or more lobes 20 which comprise concave surfaces 
extending inwardly. The tool drive mechanism 5 also comprises a cam 
follower 24 which is pivoted about a shaft 23. 
Referring to FIG. 3, the cam follower is shown in more detail. The cam 
follower 24 comprises a pivoted end 25 spaced apart from a ball race 27 by 
an elongate member 28. The ball race 27 follows the surface of the cam as 
it rotates with the driven cam, due to the rotation of the driving cog 3. 
The presence of a lobe causes ball race 27 to move towards the centre of 
the cog in a direction indicated by arrow X in FIG. 3 in order to follow 
the surface of the cam. This in turn causes the cam follower 24 to pivot 
about pivot end 25. The cam follower is connected to the tool 7 (FIG. 4) 
by means of a flexible cable 6. The cable 6 is connected to the elongate 
member 28 of the cam follower 24 at a cable pick up point 8. The position 
of the cable on the elongate member 28 may be varied by fixing the cable 
end in any one of the three cable pick up points present in the example of 
FIG. 3. The relative position of the cable end determines the sensitivity 
of the device 10. For example if the cable is connected in the cable pick 
up point which is positioned relatively close to the ball race, the pick 
up point will move a relatively greater distance than a cable pick up 
point positioned nearer to the pivot end 25 of the cam follower 24. The 
flexible cable 6 is longitudinally slidable within cable sheath 30. 
Referring now to FIG. 4, the tool 7 is shown in more detail. The tool 
comprises a housing 42 in which is moveably positioned a cutting blade 41. 
The cutting blade may move between a cutting position as shown in FIG. 4 
wherein the blade protrudes beyond the housing, and a non-cutting position 
wherein the blade has retracted by the distance of cable movement within 
the housing. The blade 41 is connected to the flexible cable 6 at an end 
remote from the cutting blade end. The blade is guided during its movement 
by a tool tip guide 47. A spring 44 biassed the blade in the operating 
position. A cable adjuster 36 allows the tension in the cable to be varied 
to suit the operating conditions. 
In use, when the driven cog 12 is being caused to rotate by the driving cog 
3, and thus causing the cam shaft and therefore the cams to rotate, the 
cam follower will follow the surface of the cam. The presence of a lobe 
will cause the ball race 27 to move radially inwardly under the action of 
the spring 44 to extend the cutting blade into its operating position. 
When the lobe has passed by the cam follower 24, the cable 6 will ensure 
that the blade returns to its non operating position. As the cam rotates, 
this action will be repeated causing the blade to reciprocate. The cam may 
include more than one lobe, and the ratio of the teeth on the driving cog 
to that of the teeth on the driven cog in conjunction with the number of 
lobes on the cam determines the rate of reciprocation on the blade 41. 
In this example, there are three cams present in the cam arrangement 35. It 
is possible to position the cam follower to follow any one of three cams. 
As can be seen from FIG. 2, the lobes on each of the three cams are offset 
from one another, and this allows different spacing and positionings of 
the cuts on the object to be decorated. This allows an elaborate pattern 
to be built up using the cutting tools 41. 
Referring to FIG. 4, the cutting blade 41 of the tool 7 is interchangeable, 
and may be changed to suit the particular application. The back of the 
cutting blade 41 and the cable adjuster guide 48 serve as abutment means 
for the spring 44. 
The following table shows the relationship between the number of teeth in 
both the driven and driving cogs, the number of positions of tool advanced 
per lobe of cam around the work, the number of revolutions of work taken 
to produce this number of positions and therefore the number of incisions 
possible from various numbers of lobes on a cam. 
TABLE 1 
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No of positions of tool 
No of revolutions of 
No of incision 
advances per lobe of 
work taken to perform 
possible from: 
Drive 
Driven 
cam around work 
same 2 Lobes 
3 lobes 
4 lobes 
6 lobes 
__________________________________________________________________________ 
44 10 22 5 44 66 88 132 
12 11 3 22 33 44 66 
13 44 13 88 132 176 264 
14 22 7 44 66 88 132 
15 44 15 88 132 176 264 
16 11 4 22 33 44 66 
17 44 17 88 132 176 264 
18 22 9 44 66 88 132 
20 11 5 22 33 44 66 
21 44 21 88 132 176 264 
__________________________________________________________________________ 
For a given cam lobe profile, the fewer teeth on the driven cog, the 
shorter the angle of rotation of the work covered by each advance of the 
cutter. 
The extent of the lobe determines the dwell angle and the depth of the lobe 
determines the lift. 
The amount of lift on a cam and the dwell angle of the lobe or lobes in 
conjunction with the gearing ratio between the driving and driven cogs and 
the drive pick up point on the cam follower together govern the number, 
length and depth of cuts made by the tool 7 in any given pattern. 
Lobes on the same cam can be cut with differing lifts and dwell angles 
offering long and short cuts or deep and shallow cuts. Cams can be fitted 
relative to each other in order that they will be "out of phase" i.e. form 
a cut between two previous cuts which have been formed when the cam 
follower is following a first cam. Thus, by having a plurality of cams, 
the possible number of cuts on a perimeter of a work to be decorated is 
increased, and other variations such as dimples between flutes are 
possible. 
For example, the cam follower may be in a position to follow a first cam, 
which results in the tool creatinng cuts on the work having a first 
spacing. The cam follower may then be moved to track a second cam, which 
may result in cuts being formed in the space between adjacent cuts in the 
first set of cuts. 
The horizontal position of the tool is governed by the operator, or 
mechanically, and the vertical position of the tool is substantially 
controlled due to the tool rest on which the tool is positioned, which may 
be horizontal or tilted in one plane. 
To illustrate the invention, when the ratio of-the driving to driven cogs 
is 2.2 to 1, a cam with one lobe produces 11 cuts per 5 revolutions of the 
work. All these cuts are positioned equidistant from one another 
circumferentially. The profile which the tool will cut is governed by the 
profile of the cam and the drive take up point on the cam follower. The 
depth of cut is also governed by the position of the tool in relation to 
the work. 
Typically, the work will rotate at a speed within the range of 250 rpm and 
500 rpm approximately. In order for the operator to see the pattern 
developing a stroboscopic light triggered by the rotation of the shaft may 
be used. 
Referring to FIG. 5 a second embodiment of the invention incorporating a 
control box 50 is shown. The ornamental turning device 51 comprises a 
shaft 52, which forms part of a lathe. Mounted on one end of the shaft 52 
is a standard chuck (not shown) for holding the work 54 to be decorated. 
In this example the work 54 comprises a wooden goblet. The device 51 
further comprises a tool drive mechanism for driving tool 55, which in 
this example is designed to be hand held. 
The tool 55 comprises a reciprocating blade which is controlled by a 
flexible cable 56. The control box 57 ensures that the blade of the tool 
55 reciprocates at a rate proportional to the rate of rotation of the 
shaft 11, in a manner to be described below. 
The drive mechanism 53 comprises an infra red sensor (not shown), which 
detects the rotational position of the work piece by means of a series of 
holes 58 in a disc 59 which is mounted on the same shaft 52 as the work 
54. The information relating to the rotational position of the work piece 
54 is processeed by a microprocessor 60, which is programmed by the 
operator using the controls 61 on the control box 50, to energise a 
solenoid (not shown) which is positioned within the body of the hand held 
tool 55. This both propels and withdraws the cutter 62 which is mounted at 
the end of the tool, towards and away from the work piece 54 at 
predetermined intervals around the circumference of the work piece 54 as 
it rotates. The speed of rotation is between 250 rpm and 400 rpm 
approximately. 
In use it allows the operator to decorate work in the same manner as with a 
device described with reference to FIGS. 1 to 4, which is a purely 
mechanical device. However there is an added advantage that the operator 
is able to vary the position and number and length of cuts per 
circumference as desired. In other words, it is possible to make a series 
of cuts, for example, on only one side of a piece of work instead of all 
the way Pound the circumference of that piece of work, or to make groups 
of cuts having any desired space between the group.