Improvements in Turning Lathes for Producing Round, Oval, Poly- gonal and other Shapes upon Wood, Metal and other Substances.
Year: 1898

page_text: Improvements in Turning Lathes for Producing Round, Oval, Poly-
gonal and other Shapes upon Wood, Metal and other Substances.
I, FRANKLIN WISE HOWORTH, of No. 46, Lincoln's Inn Fields, in the County
of London, Chemist, (a communication from abroad by Julius Hermon Weiss,
28, Faubourg Montmartre, Paris, France, Merchant), do hereby declare the nature
of this invention to be as follows:-
:-
This invention relates to the art of turning wood, metal and other material
which is of sufficient firmness to be shaped by cutting. The invention is largely
independent of any particular mechanical apparatus, as the principle underlying
it readily adapts itself to the various well-known devices commonly used to
impart rotary and reciprocating movements.
Various turning lathes of widely different construction have been heretofore
employed for producing either round or many-sided work. All such lathes,
however, have proceeded on well-known lines and have failed to embody or
utilize the theoretical mathematics upon which this invention is founded.
The object of this invention is to endow turning lathes with the capacity of
making a great variety of independent geometrical motions, and so to inter-
combine these independent motions as to produce an immense variety of pro-
ducts with comparatively insignificant changes in such intercombination and to
operate such lathes at a high rate of speed, whereby not only entirely novel
shapes may be produced, but old and standard shapes may be produced with
greater rapidity and, therefore, at much smaller expense.
Previous attempts in this line have failed owing to the absence of the under-
lying principle or mathematical conception which is about to be set forth and
which is this:—
The ultimate shape of a turned object does not depend primarily upon the
shape of the cutting tool, nor upon the character of the motion of the moving
parts of the machine, nor. upon the selection of means for producing the required
motions; but does depend primarily upon the time and place of intersection of
the various potential motions and upon the relative speed and direction of those
motions at the time of intersection.
With any given devices for operating the cutter-head, chuck and cutting-
tool; with any fixed shape for the individual cutters, and with all the other
details of the machine unchanged; in other words, with an apparatus so con-
stituted as uniformly to produce a fixed character of motion in all the moving
parts thereof; a large variety of products may be produced by slight alterations
in the points of intersection of these motions.

page_text: Otherwise stated, the principle involved in this invention is that it is not the
motions (simple or complex) of the cutting-tool and the substance cut which
impress character upon the object produced, but it is the intercombination of
the points of intersection of the paths of the cutting-tool and of the substance
to be cut which impress such character, having regard to such details as relative
speed, relative direction and the extent to which one path cuts into the other.
With this principle in view and without the use of patterns, formers, special
cams, etc., all desired shapes of turned work may be rapidly, accurately and
continuously produced by adjusting the speed of rotation and the time and
character of reciprocation so as to make the effective points of intersection of
the paths of the cutter and of the object to be cut come where they ought to
come on geometrical principles to produce the shape sought. In other words,
by imagining any geometrical figure desired and determining the initial points
of intersection of the paths of the cutter and the wood needed to produce the
salient points of said figure and then determining the direction and speed of
the paths at their intersecting points necessary to produce the subordinate out-
lines of said figure; any turning lathe, whether of the baluster, automatic or
other type, can be readily adjusted so that the paths actually described by the
cutter and the wood will intersect at the pre-determined points with the appro-
priate speed, frequency and direction and not intersect at other effective points.
By effective points of intersection are meant, of course, points of intersection
which take place under such conditions that the cutter comes in contact with
something to cut. Of course, the sweep of the cutter through space left vacant
by the absence of any material to be cut becomes an ineffective intersection of
the original paths.
This adjustment, which mathematically described may seem difficult to
embody in machinery, is exceedingly simple and it has been found in practice
that as many as twenty-five or thirty different shapes can be produced by the
same driving cam, and that a single cutter of given outline can be used in
cutting sixty varieties of work.
Gears, cams, rock-shafts, pitmans, chuck-carriages, reciprocating bed-plates,
eccentrics, tail-stocks and the various other devices used in the art of turning
are so well-known and have been so many times described that it seems unneces-
sary and perhaps misleading to illustrate any special form of machine to embody
the above described principle. It must be understood that a turning lathe to
operate under this new principle of turning must be provided with some
mechanical device by which the cutter-head can be caused to revolve at a high
rate of speed (carrying preferably a centrifugal cutter) and to move into and
out of the path of the object to be shaped. There must also be some mechanical
device from which the wood receives a continuous rotation as the wood is carried
toward or from the revolving cutter. There must also be mechanical means
provided for altering and adjusting the relative speed of revolution of the wood
with regard to the to-and-fro motion of the bed-plate or chuck-carriage.
While some mechanical devices of this kind are required, the practical turner
can be left to select among the various devices available those which he prefers
for the particular work which he designs to make.
In the accompanying drawings therefore, is illustrated the work required of
the mechanical device rather than the device itself, and I have taken a five-
sided figure for the purpose of illustration, it being obvious that the same prin-
ciple applies to all sorts of shapes from the oval (which may be regarded as a
two-sided figure) up to the circle (which may be regarded as a polygon with an
indefinite number of sides).
Fig. 1 represents a pentagon the sides of which are right lines. Fig. 2 shows
a similar pentagon with concave sides and Fig. 3 a similar pentagon with convex
sides.
It is wholly immaterial what the original shape of the block, from which

page_text: these pentagons are to be cut, was, provided, of course, it was large enough to
embrace the desired shape in its cross-section.
To produce a five-sided figure, the speed of revolution of the wood to that of
the reciprocation of the chuck-carriage should be as one to five. Whatever may
be the speed of revolution of the cutter and whatever may be the device whereby
rotation is communicated to the wood-chuck, the chuck should revolve once
only for every five to-and-fro slides of the chuck-carriage.
This adjustment must be accurate, as otherwise, as the cutter creeps into the
wood to reduce the latter to the desired size as well as shape, the successive cor-
responding blows would not be given with proper accuracy and irregular work
would result.
It is to be noticed that if the bed-plate which carries the wood-chuck makes
only one to-and-fro motion for each revolution of the wood in the chuck, the
result will be round work, whatever may be the speed of the cutter, unless the
cutter also has a reciprocating motion, the centre of the round work being
eccentric to the centre of the wood chuck. If the bed plate reciprocates twice
for each revolution of the wood, the result will be an oval. Three reciproca-
tions will make a triangular figure and so on. Any mechanic can so adjust the
driving mechanism of the bed-plate as to communicate to the latter a to-and-fro
movement as many times the revolution of the wood as corresponds to the
number of sides to be given thereto.
A high speed of revolution for the cutting tool (in practice from four to
seven thousand revolutions a minute) is necessary to secure a marketable pro-
duct, whether round or many-sided work is desired. Where turning is done
with a stationary tool, the material removed by the cutting-tool takes the form
of a continuous shaving and if the tool is sharp and the revolution steady, the
cut surface will be smooth. Where the cutter is mounted in a revolving disc
or cutter-head, so that it strikes the wood only once for each revolution, the
material is cut away in the form of very small chips. There is no continuous
shaving and the sharpness of the tool alone does not suffice for the production
of smooth work. This smoothness is approximated more and more as the speed
of revolution of the cutting-tool increases, and it has been found, in practice,
that a speed of 5400 revolutions a minute is a very good speed for most kinds
of work.
The normal tendency of the revolving cutter, when the revolving wood is
brought in contact with it, is, like a stationary cutter, simply to produce round-
work, and the departure from round-work is brought about by the reciprocation
of the revolving wood.
Whatever may be the number of sides to be given to the wood, half of each
side is cut during the "to"-motion of the bed-plate, and the other half during
the fro" motion.
"
The normal tendency of the revolving cutter is to cut a concave surface and
this tendency is so modified by the to-and-fro motion of the chuck-carriage that,
if no attention were paid to the details of movement of the latter, each side of
the figure produced would be half convex and half concave, as shown in Fig. 4.
This obviously follows from the fact that the wood advances toward the centre
of rotation of the cutter in the to "-motion and retreats from said centre in
the fro" motion; the cutter, of course, being always in contact with some
part of the wood during the process.
"
Many mechanical devices may be used for modifying and correcting this ten-
dency of the cutter. It may be done by a cam such as described or by any
device which so affects the length of slide given to the chuck-carriage and the
time consumed in making this slide to and fro, that the natural simple operation
of the wood is continually controlled and checked to accomplish the purpose
in view.
For instance, if it is desired to produce a figure with concave-sides like Fig. 2,

page_text: devices must be used of such character that, without interfering with the
rythmic reciprocation of the bed-plate, the retreating wood is held up to the
cutter during the fraction of a second needed to complete the second half of
the concave stroke. If a convex-sided figure like Fig. 3 is desired, the devices
which control the slide of the bed-plate must be so constructed that the advanc-
ing wood is held away from the cutter during the fraction of a second needed
to produce the first half of the convex stroke.
If a straight-sided figure like Fig. 1 is desired, the action of the wood must
be controlled during the entire stroke so that each succeeding part of this wood,
as it revolves, is presented to the revolving cutter edge in the same way; that
is those parts which would naturally be too far advanced must be held back
and those which would naturally be too far back must be pushed forward.
The cam herein before described as used to produce this effect must not be
confused with the cams heretofore employed in turning, because the shape of
the cam which is used in this invention bears no resemblance whatever to the
shape of the product produced. The lines of the cam (if a cam is used) are
derived mathematically from the exigencies of the figure desired and the same
shaped cam as before stated can be used for as many as twenty-five or thirty
different figures.
As before stated, this mathematical embodiment of the theoretical lines
required by the figure desired does not necessitate the employment of a cam.
Any mechanical device will do for imparting this compensatory movement to
the bed-plate which embodies the following idea:-
The extreme slide of the bed-plate being fixed and the effective part of the
slide being the part which takes place while the wood is being cut, the character
of the cut received by the wood will vary (all other things being equal) with
the rapidity with which the wood is moving through the effective portion of the
slide. In other words, by varying the time of the slide without varying its length
or by varying the length without varying the time, a compensatory movement
is produced by which a normal concave can be turned to a normal convex, or vice
versa, or a normal curve converted into a right line.
It will thus be seen that the finish of the product depends upon the speed of
the revolving cutter and the shape of the product depends upon the intercombina-
tion of the paths of the rotating and reciprocating cutter and the rotating and re-
ciprocating wood as modified by the conditions of speed, time, distance and direc-
tion imposed upon those paths as a resultant of the requirements of a pre-
conceived geometrical shape, the production of which is desired.
The above explanation would seem to be sufficient for all symetrical figures
of whatever number of sides.
Obviously in making symetrical figures, the various movements of the machine
must be in harmony with each other; but this harmony may be partially or
wholly destroyed and produce very different shapes.
Thus, instead of having the wood approach the cutter-head uniformly during one
half of the operation, and recede uniformly during the other, its to-and-fro move-
ments may be so varied that it gains or loses intermittently, whereby variations
in the depth or character of cut may be obtained. By imparting a slow inter-
mittent lateral feed to either the wood-carriage or the cutter-carriage, what is
commonly known as spiral or twist work can be produced, the wood being given
automatically a very slight partial turn whenever the cutter is withdrawn from
contact with it.
Illustrations of the embodiment of the mathematical principle which is thus
described in machinery, could be given in great number; but it is thought that
the above is sufficient to make it evident that the things for the turner to do in
the application of this principle are, first, to block out mentally in the machine
a space similar in shape and size to the object which he desires to produce and
give to the wood a revolution as many times slower than the to-and-fro motion
of the chuck-carriage as there are sides to said space and then so adjust the

page_text: details of the approach of the wood chuck to the revolving cutter, that however
often either the wood or the cutter may enter said mentally blocked out space,
they never come in contact with each other therein, and the successive points
of contact between the cutter and the wood constantly approach and eventually
coincide with the mathematical periphery of said space.
At this point, the effective operation of the machine ceases and the finished
product should be removed and another block substituted.
Improvements in Turning Lathes for Producing Round, Oval, Poly-
gonal and other Shapes upon Wood, Metal and other Substances.
A communication from abroad by JULIUS H. WEISS, of 28, Faubourg Mont-
martre, Paris, France, Merchant.
I, FRANKLIN WISE HOWORTII, of 46, Lincoln's Inn Fields, in the County of
London, Chemist, do hereby declare the nature of this invention, and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:-
This invention relates to the art of turning wood, metal and other material
which is of sufficient firmness to be shaped by cutting. The invention is largely
independent of any particular mechanical apparatus, as the principle underlying
it readily adapts itself to the various well-known devices commonly used to
impart rotary and reciprocating movements.
Various turning lathes of widely different construction have been heretofore
employed for producing either round or many sided work. All such lathes,
however, have proceeded on well known lines and have failed to embody or
utilize the theoretical mathematics upon which this invention is founded.
The object of this invention is to endow turning lathes with the capacity of
making a great variety of independent geometrical motions, and so to inter-
combine these independent motions as to produce an immense variety of pro-
ducts with comparatively insignificant changes in such intercombination and to
operate such lathes at a high rate of speed, whereby not only entirely novel
shapes may be produced, but old and standard shapes may be produced with
greater rapidity and, therefore, at much smaller expense.
Previous attempts in this direction have failed owing to the absence of the
underlying principle or mathematical conception which will now be set forth and
which is as follows:-
The ultimate shape of a turned object does not depend primarily upon the
shape of the cutting tool, nor upon the character of the motion of the moving
parts of the machine, nor upon the selection of means for producing the required
motions; but does depend primarily upon the time and place of intersection of
the various potential motions and upon the relative speed and direction of those
motions at the time of intersection.
With any given devices for operating the cutter-head, chuck and cutting-
tool, with any fixed shape for the individual cutters and with all the other
details of the machine unchanged; in other words, with an apparatus so con-
stituted as uniformly to produce a fixed character of motion in all the moving
parts thereof, a large variety of products may be produced by slight alterations
in the points of intersection of these motions.

page_text: Otherwise stated, the principle involved in this invention is that it is not the
motions (simple or complex) of the cutting tool and the substance cut which
impress character upon the object produced, but it is the intercombination of
the points of intersection of the paths of the cutting tool and of the substance
to be cut (hereinafter referred to as wood) which impress such character, having
regard to such details as relative speed, relative direction, and the extent to
which one path cuts into the other.
With this principle in view and without the use of patterns, formers, special
cams, or the like, all desired shapes of turned work may be rapidly, accurately
and continuously produced by adjusting the speed of rotation and the time and
character of reciprocation so as to make the effective points of intersection of
the paths of the cutter and of the object to be cut come where they ought to
come on geometrical principles to produce the shape sought. In other words,
by imagining any geometrical figure desired and determining the initial points
of intersection of the path of the cutter and the wood needed to produce the
salient points of said figure and then determining the direction and speed of
the paths at their intersecting points necessary to produce the subordinate out-
lines of said figure, any turning lathe, whether of the baluster, automatic or
other type, can be readily adjusted so that the paths actually described by the
cutter and the wood will intersect at the predetermined points with the appro-
priate speed, frequency, and direction, and will not intersect at other effective
points.
By effective points of intersection are meant, of course, points of intersection
which take place under such conditions that the cutter comes in contact with
something to cut. Of course, the sweep of the cutter through space left vacant
by the absence of any material to be cut becomes an ineffective intersection of
the original paths.
This adjustment, which, mathematically described may seem difficult to
embody in machinery, is exceedingly simple and it has been found in practice
that as many as twenty-five or thirty different shapes can be produced by the
same driving cam, and that a single cutter of given outline can be used in
cutting sixty varieties of work.
Gears, cams, rock-shafts, pitmans, chuck-carriages, reciprocating bed-plates,
cccentrics, tail-stocks and the various other devices used in the art of turning
are so well known and have been so many times described, that it may be
unnecessary to illustrate any special form of machine to embody the above
described principle. It must be understood that a turning lathe to operate
under the new principle of turning herein before set forth, must be provided
with some mechanical device by which the cutter-head (carrying preferably a
centrifugal cutter) can be caused to revolve at a high rate of speed and with
means for moving the cutter head into and out of the path of the object to be
shaped. There must also be some mechanical device from which the wood shall
receive a continuous rotation as the wood is carried toward or from the revolving
cutter. Mechanical means must also be provided for altering and adjusting
the relative speed of revolution of the wood with regard to the to-and-fro motion
of the bed-plate or chuck-carriage.
While some mechanical devices of this kind are required, the practical turner
can be left to select among the various devices available, those which he prefers
for the particular work which he designs to make.
In the accompanying illustrative drawings, there is shown a five-sided figure
for the purpose of illustration, it being obvious that the same principle applies
to all sorts of shapes from the oval, (which may be regarded as a two-sided
figure), up to the circle (which may be regarded as a polygon with an indefinite
number of sides). A baluster lathe is also shown as a good type to illustrate
the work required of the mechanical devices rather than as a specific device itself.
Figs. 1, 2, 3 and 4 are illustrations of pentagons which might be cut when
the reciprocations of the chuck-carriage of the lathe to the revolution of the

page_text: wood are as five to one. Fig. 1 represents a pentagon the sides of which are
right lines. Fig. 2 shows a pentagon with concave sides and Fig. 3 another
pentagon with convex sides. Fig. 4 shows a pentagon to be hereinafter
referred to.
It is wholly immaterial what is the original shape of the block from which
these pentagons are to be cut, provided of course that it is large enough to
embrace the desired shape in its cross section.
To produce a five-sided figure, the speed of revolution of the wood to that of
the reciprocation of the chuck-carriage should be as one to five. Whatever may
be the speed of revolution of the cutter and whatever may be the device whereby
rotation is communicated to the wood-chuck, the chuck should revolve once
only for every five to-and-fro sliding movements of the chuck carriage. This
adjustment must be accurate, otherwise, as the cutter creeps into the wood to
reduce the latter to the desired size as well as shape, the successive correspond-
ing blows of the cutter would not be given with proper accuracy, and irregular
work would result.
It is to be noticed that if the bed-plate which carries the wood chuck makes,
through the medium of a cam of suitable shape, only one to-and-fro motion for
each revolution of the wood in the chuck, the result will be round work, what-
ever may be the speed of the cutter, unless the cutter also has a reciprocating
motion, the centre of the round work being eccentric to the centre of the wood-
chuck. If the bed-plate reciprocates twice for each revolution of the wood, the
result will be an oval. Three reciprocations will make a triangular figure and
so on. Any mechanic can so adjust the driving mechanism of the bed-plate as
to communicate to the latter a to and fro movement as many times the revolu-
tion of the wood as corresponds to the number of sides to be given thereto.
Figs. 5 and 6 are rear side and end elevations respectively, and Fig. 7 a trans-
verse section, showing so much of a baluster lathe as is necessary to illustrate
the work required of the mechanical devices.
1 is the framework of the lathe upon which the moving parts are mounted,
2 is a cone driving pulley fixed on a shaft 3 that is journalled in brackets 3"
projecting from the framework, and is driven by belting from a source of
power not shown. The shaft 3 carries near its outer end a small gear wheel 4
which meshes with a large gear wheel 5 mounted upon a shaft 6 carried by the
outer end of an arm 7 mounted upon a cam shaft 8, journalled in the framework,
as shown.
The cam-shaft 8 carries at one end a gear wheel 9 which meshes with and is
driven by the gear wheel 5. The three gear wheels 4, 5 and 9 form what is
known as a multiple gear system and are the means by which the proportionate
revolution and reciprocation of the wood held in the chuck are obtained. What-
ever rotation is received by the cam-shaft 8 is, as will be hereafter explained,
transmitted to the reciprocating bed-plate on which the chuck-carriage is
mounted, through the medium of a rock-shaft, so that if the cam shaft 8 revolves
two, three, four or more times while the wood in the chuck is revolving once, it
is obvious that the chuck which carries the wood will reciprocate the corre-
sponding number of times.
As a part of the said system, the intermediate gear wheel 5 is preferably
made the changeable one, although either or both of the other wheels could be
removed and others of different size substituted, if preferred. It will be readily
understood that by predetermining the respective number of teeth in the
different wheels in this multiple gear system, a single revolution of the driving
shaft 3 may be converted into as many or as few revolutions of the cam-shaft 8
as may be desired.
In the baluster lathe which I have taken as an example, the reciprocation of
the chuck carriage is derived from the cam-shaft 8 as follows:-At the inner
end of the shaft is a cam 10 (Fig. 7) which revolves with it and by reason of its
irregular surface, displaces a rocking arm 11 fixed to a rock-shaft 12 which is

page_text: journalled in the frame-work. Upon the boss of the rocking arm 11 is freely
inounted another arm 11ª, the ends of the two arms being connected by a tension
spring 11b, the arrangement being such as to keep the rocking arm in close
contact with the cam 10. Each part 11, 11" of the double rocking arm carries
a roller 11 which travels over the surface of the cam 10 and being displaced by
the irregular surface thereof, communicates a rocking movement to the rock-
shaft 12, in a manner that will be readily understood. 13-13 are short crank
arms provided at each end of the rock-shaft 12 and connected by rods 14 to the
under side of the bed-plate 15 upon which the chuck carriage is mounted. This
bed-plate moves back and forth upon a track 15" secured to the framework in
the manner usual to sliding bed-plates and will obviously receive one to-and-fro
movement for every revolution of the cam-shaft 8.
The character of the cam 10 determines the character of the reciprocation of
the bed-plate. It is obvious that if the outline of the cam 10 is such as to make
the outward movement of the rollers 11° of the same duration as their inward
movement, the to-and-fro sliding movements of the bed-plate will be alike. If,
however, the outline of the cam is such that the inward motion of the rollers is
more abrupt than the outward motion, the to-and-fro sliding movements of the
bed-plate will not be alike, but will vary, in that one will take place quickly
and the other slowly. Hence, opportunity is afforded by substituting cams of
various outline for the cam 10, for producing a great variety in what may be
called the subordinate features of the reciprocation of the bed-plate. The object
of this variation will be hereinafter made clear.
In the example of baluster lathe herein used for purposes of illustration, the
chuck carriage is in the form of a reel mounted upon and carried by the bed-
plate 15. The reel comprises three discs 16", 16, 16 held together by four screw-
bolts 16d, the two outer plates 16", 16°, being fixed endways, and the middle
plate 16b being movable along the bolts to accommodate the chuck reel to various
lengths of material. The plates 16", 16 carry two chucks, or more exactly
speaking, two chucks 17 on one plate 16 and two tail-stocks 18 on the other
plate 16, a chuck and tail-stock together constituting a chuck in the full sense.
By providing two chucks, one can remain idle in order that the finished product
may be removed and new stock inserted, while the other chuck is in operation.
Rotary movement is imparted to the active chuck from a worm-wheel 19 as
follows:
The driving-shaft 3 carries a bevelled gear-wheel 20 Fig. 6, which meshes with
a bevelled gear wheel 21 upon a worm-shaft 22 running along the end of the
lathe and carrying a worm 23 which engages the worm-wheel 19. This worm-
wheel is mounted on a shaft 24 journalled in posts rising from the reciprocating
bed-plate 15. Through this shaft slides a clutch-shaft 25 which carries upon
its inner end a clutch, not shown, which is adapted to fit into the outer end of
the chuck and thereby cause the same to revolve with the speed of the worm-
wheel 19. This clutch is brought into and out of engagement with the chuck
by a clutch-rod 26 operated from the forward end of the lathe in the usual
manner.
27 is the ordinary operator's wheel at the forward end of the lathe and so
connected in the usual manner by suitable devices with the cutter carriage that
the operator may accurately control the extent to which the revolving cutter
can reach into or intersect the path of the revolving and reciprocating wood.
This wheel is used to bring the revolving cutter into action for every new piece
of wood to be cut and out of action while the chuck reel is turned to present a
new piece of wood.
28 represents a series of revolving cutters mounted upon the cutter arbor 29.
This cutter arbor is journalled in boxes 30-30 mounted upon the cutter carriage
or bed-plate 31 which is adapted to move on the track 31ª under control of
the operator's wheel 27.

page_text: A high speed of revolution for the cutting tool (in practice, from four to
seven thousand revolutions a minute) is necessary to secure a marketable pro-
duct, whether round or many sided work is desired, and this speed is attained
by the direct application of belting, not shown, to a pulley 29 secured to the
cutter arbor 29.
Where turning is done with a stationary tool, the material removed by the
cutting tool takes the form of a continuous shaving and if the tool is sharp and
the revolution steady, the cut surface will be smooth. Where the cutter is
mounted in a revolving disc or cutter-head, so that it strikes the wood only
once for each revolution, the material is cut away in the form of very small chips.
There is no continuous shaving and the sharpness of the tool alone does not
suffice for the production of smooth work. This smoothness is approximated
more and more as the speed of a revolution of the cutting tool increases and
it has been found in practice that a speed of 5,400 revolutions a minute is a
very good speed for most kinds of wood work.
The normal tendency of the revolving cutter when the revolving wood is
brought into contact with it, is, like a stationary cutter, simply to produce round-
work and the departure from round-work is brought about by the reciprocation
of the revolving wood.
Whatever may be the number of sides to be given to the wood, half of cach
side is cut during the to" motion of the bed-plate and the other half during
the "fro" motion.
The normal tendency of the revolving cutter is to cut a concave surface and
this tendency is so modified by the to-and-fro motion of the chuck-carriage that
if no attention were paid to the details of movement of the latter, each side of
the figure produced would be half convex and half concave as shown in Fig. 4.
This obviously follows from the fact that the wood advances toward the centre
of rotation of the cutter in the "to" motion and retreats from said centre in
the "fro" motion; the cutter, of course, being always in contact with some
part of the wood during the process.
Many mechanical devices may be used for modifying and correcting this
tendency of the cutter. It may be done by a cam like the cam 10, or by any
device which so affects the length of the sliding movement given to the chuck-
carriage and the time consumed in making this carriage slide to and fro, that
the natural simple operation of the wood is continually controlled and checked
to accomplish the purpose in view.
For instance, if it be desired to produce a figure with concave sides like Fig. 2,
devices must be used of such character that without interfering with the
rythmic reciprocation of the bed-plate, the retreating wood is held up to the
cutter during the fraction of a second needed to complete the second half of
the concave stroke. If a convex-sided figure like Fig. 3 is desired, the devices
which control the sliding movement of the bed-plate must be so constructed
that the advancing wood is held away from the cutter during the fraction of a
second needed to produce the first half of the convex stroke.
If a straight-sided figure like Fig. 1 is desired, the action of the wood must
be controlled during the entire stroke, so that each succeeding part of the wood.
as it revolves is presented to the revolving cutter edge in the same way that
is, those parts which would naturally be too far advanced must be held back
and those which would naturally be too far back must be pushed forward.
The cam 10 used to produce this effect must not be confused with the cams
heretofore employed in turning, because the shape of the cam used according to
this invention bears no resemblance whatever to the shape of the product pro-
duced. The lines of the cam are derived mathematically from the exigencies
of the figure desired and the same shaped cams, as before stated, can be used
for as many as twenty-five or thirty different figures.
As before stated, this mathematical embodiment of the theoretical lines

page_text: required by the figure desired does not necessitate the employment of a cam.
Any mechanical device will do for imparting this compensatory movement to
the bed-plate which embodies the following idea :-
The extreme sliding movement of the bed-plate being fixed and the effective
part of the movement being the part which takes place while the wood is being
cut, the character of the cut received by the wood will vary, (other things being
equal) with the rapidity with which the wood is moving through the effective
portion of the sliding movement. In other words, by varying the time of the
sliding movement without varying its length, or by varying the length without.
varying the time, a compensatory movement is produced by which a normal
concave can be turned to a normal convex or vice versa, or a normal curve con-
verted into a right line.
It will thus be seen that the finish of the product depends upon the speed of
the revolving cutter, and the shape of the product depends upon the intercom-
bination of the paths of the rotating cutter and the rotating and reciprocating
wood as modified by the conditions of speed, time, distance and direction imposed
upon those paths as a resultant of the requirements of a pre-conceived
geometrical shape, the production of which is desired.
The above explanation would seem to be sufficient for all symmetrical figures
of whatever number of sides.
Obviously, in making symmetrical figures, the various movements of the machine
must be in harmony with each other; but this harmony may be partially or
wholly destroyed and produce very different shapes:
Thus, instead of having the wood approach the cutter head uniformly during
one half of the operation and recede uniformly during the other, its to-and-fro
movements may be so varied that it gains or loses intermittently, whereby varia-
tions in the depth or character of cut may be obtained. By imparting a slow inter-
mittent lateral feed to either the wood-carriage or the cutter-carriage, what is
commonly known as spiral or twist work can be produced, the wood being given
automatically a very slight partial turn whenever the cutter is withdrawn from
contact with it.
Illustrations of the embodiment of the mathematical principle which is thus
described in machinery could be given in great number; but it is thought that
the above is sufficient to make it evident that the things for the turner to do in
the application of this principle are, first, to block out mentally in the machine
a space similar in shape and size to the object which he desires to produce;
secondly, to give to the wood a revolution as many times slower than the to and
fro motion of the chuck-carriage as there are sides to the said space, and then
to so adjust the details of the approach of the wood chuck to the revolving cutter
that, however often either the wood or the cutter may enter the said mentally
blocked out space, they never come in contact with each other within the said
space, and that the successive points of contact between the cutter and the wood
shall constantly approach and eventually coincide with the mathematical peri-
phery of the said space. At this point, the effective operation of the machine
ceases and the finished product should be removed and another piece of wood
substituted.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is-
1. A turning lathe provided with suitable devices for imparting a high speed
of revolution to the cutter or cutters, a reciprocating movement to the carriage
for the wood or other material to be cut, and a proportionate revolution to the
work chuck carried thereby, and with suitable adjusting devices, whereby the
said cutter or cutters and the material carried by the said chuck are caused to
enter and leave each other's paths of revolution in such a manner that the said
cutter or cutters and the said material will come into contact with each other at

page_text: points successively approaching and ultimately coinciding with but never pass-
ing within the periphery of a predetermined space of the shape and size of the
object to be produced, so that the material carried by the said chuck will be cut
to the shape and size of the said space without the use of any copy, pattern,
former or similar device.
2. In a turning lathe having rotary cutters as set forth, the combination with
the chuck carriage and its work chuck, of reciprocating means constructed,
arranged and operating substantially in the manner hereinabove described with
reference to and shown in the drawings for the purpose set forth.
Dated this 17th day of February 1899
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C.