AN IMPROVED MACHINE FOR CUTTING SCREWS AND SPIRAL MOULDINGS
Year: 1876

page_text: LETTERS PATENT to Robert Henry, of the City and County of Perth, North
Britain, Cabinet Maker, for the Invention of "AN IMPROVED MACHINE FOR
CUTTING SCREWS AND SPIRAL MOULDINGS."
Sealed the 28th November 1876, and dated the 8th July 1870.
PROVISIONAL SPECIFICATION left by the said Robert Henry at the Office
of the Commissioners of Patents on the 8th July 1876.
ROBERT HENRY, of the City and County of Perth, North Britain, Cabinet Maker.
"AN IMPROVED MACHINE FOR CUTTING SCREWS AND SPIRAL MOULDINGS."
This Invention, which relates to improvements in cutting screws and spiral
mouldings, has for its objects accuracy in maintaining any desired pitch, economy
by dispensing with change wheels, and the production of screws or spiral mouldings
of small diameter and of any required length. It consists of revolving cutters,
either formed in or attached to a face plate secured to the end of a spindle carried
longitudinally in a head similar to the fast head of an ordinary turning lathe, which
is secured to a bed plate of any convenient form, fixed to the ways of the frame or
stand of the machine, and provided with segmental slots, through which are passed
rods or screws supporting a rest made in two portions, one of which is removed
after cutting or turning has commenced. The cutters are of a dished or concave
form, having the cutting edges shaped to suit the pattern of the screw or moulding
to be cut, and the latter is fed by means of an adjustable wheel revolving opposite
the edge of the cutters and in the same direction therewith, while its milled
periphery bears on the rod or cylinder to be cut, the latter lying in the rest at the
required angle to produce the spiral thread. The action of the milled feeding wheel
combined with that of the cutters produces a revolving and horizontal motion of
the rod or cylinder whereby the spiral cutting is effected.
The removable portion of the rest herein-before mentioned is fitted with a
vertically adjustable slide containing a sphere or ball, which is also vertically
adjustable, and a short rod or shaft which passes through it, the end thereof
which is next the cutters being fitted with a disc containing studs or pins designed
to enter corresponding holes or concavities in the end of the rod or cylinder to be
The opening in the sphere or ball to admit the rod or shaft aforesaid is of
such dimensions as to allow displacement of the latter in either direction from
the centre of the sphere or ball. On the end of the shaft or rod next to the sphere
or ball and near where it passes therethrough is another disc, provided with set
[Price Gd.]
cut.

page_text: screws which bear on the outside of the sphere or ball and by raising or lowering
the latter a horizontal motion is imparted to the shaft or rod, and consequently to
the rod or cylinder to be cut, and the extent of this horizontal motion may be
accurately maintained throughout the cutting or turning of the screw or moulding
by means of combs having edges cut to suit the various patterns of screws or
mouldings. These combs are placed in a groove or ledge running underneath and
parallel to the rod or cylinder being turned, and the threads or grooves of the latter
fitting into the comb slipping is prevented and undue horizontal motion obviated.
The slide having been adjusted and the cutting commenced the portion of the
rest containing the slide is removed and the cutting continued, the adjustable
mechanism being only necessary at the commencement of cutting screws
moulding in metal, as in the case of wood the depth of the cut in proportion to
the pitch ensures sufficient accuracy. The rod or cylinder in process of turning
travels through the permanent portion of the rest, and is further held up by
adjustable supports placed at the requisite distances. The rest is adjustable in the
segmental slots of the bed plate to any desired angle with the axis of the spindle
to which the cutters are indirectly attached, and different pitches obtained by
vertical adjustment as herein-before described. Each end of the spindle may be
fitted with cutters and provided with a rest whereby screws or mouldings may be
cut at each end of the machine.
or
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Robert Henry in the Great Seal Patent Office on the 8th January 1877.
ROBERT HENRY, of the City and County of Perth, North Britain, Cabinet Maker.
"AN IMPROVED MACHINE FOR CUTTING SCREWS AND SPIRAL MOULDINGS."
My said Invention, which relates to improvements in cutting screws and spiral
mouldings, has for its objects accuracy in obtaining any desired pitch, economy by
dispensing with change wheels and pattern screws, and the production of screws or
spiral mouldings of any required diameter and length. It consists of revolving
cutters secured to the ends of a spindle carried longitudinally in a head fixed
to the top of a table or stand, which may be of any convenient form and height,
and provided with slits or openings in which are fitted slide blocks which support
a compound rest made, constructed, and arranged as herein-after described. The
cutters are of a dished, concave, or other suitable form, having the cutting edges
shaped to suit the pattern of the screw or moulding to be cut. Sometimes the
cylinder of wood or other material, as the case may be, is fed by means of an
adjustable wheel fixed opposite the cutters, while its milled periphery bears on the
rod or cylinder to be cut, the latter lying in the hollow of the rest at the required
height and angle corresponding to the required pitch of screw or spiral moulding
to be produced. The action of the milled feeding wheel combined with that of the
cutter produces a revolving motion of the cylinder whereon the screw or spiral
cutting is to be effected.
.
The apparatus for starting the cutting of the screw or spiral moulding is fitted
on the top of the table and brought in connection with the wood or other material
on which the screw has to be cut during the time of starting it only. It consists of
a sphere which is adjustable eccentrically either in a vertical or horizontal direction,
and of a shaft which passes through it, the end thereof which is next the cutters
being fitted with a "butterfly centre" similar to that used for holding wood in the
fast head of an ordinary turning lathe. There is an opening in the sphere of such
size as to admit the shaft and allow displacement of the sphere in either direction
from its centre, or displacement of the shaft relatively with the centre of the sphere.
Near where the shaft passes through the sphere is a disc provided with screws
having conical or hemispherical points which bear on the outside of the sphere, and
by raising or lowering the latter a horizontal motion is imparted to the shaft as it

page_text: moves through a revolution by virtue of the points of the screws being in contact
with the eccentrically situated surface of the sphere. This horizontal motion is
consequently imparted to the cylinder to be cut during its first revolution, and the
extent of this horizontal motion may be accurately maintained throughout the
cutting of the screw or moulding by means of a comb or guide having projections
or teeth of the form adapted to suit the pattern of screw or moulding. These
combs or guides are placed in a groove or hollow of the rest, the projections or teeth
of the former fitting into those made on the cylinder slipping is thereby prevented
and undue horizontal motion obviated. The slide block which supports the rest
having been adjusted and the sphere displaced to the proper amount corresponding
to the pitch, and one turn of the screw or moulding cut, the portion of the mechanism
containing the sphere is removed and the cutting continued, the adjustable
mechanism for starting the thread being only necessary at the commencement of
cutting screws or shallow mouldings, as in ordinary cases of spiral cutting in wood
the depth of the cut ensures sufficient accuracy of pitch without the use of combs or
patterns. The cylinder in process of being cut passes along the hollow of the rest,
and may be further held by adjustable supports placed at the extremities of the top
of the table. The rest is adjustable to any desired height and to any required
angle to the axis of the spindle to which the cutters are attached; and different
Each end
pitches are obtained by vertical adjustment as herein-before described.
of the spindle is preferably fitted with cutters, and provided with a slide rest
whereby right or left hand screws or mouldings can be cut, one end for right and
the other for left hand screws or mouldings.
And in order that my said Invention may be properly understood I now proceed
more particularly to set forth the system, mode, or manner in or under which the
same is or may be used or practically carried into effect, reference being had to the
annexed Sheets of Drawings and to the letters and figures marked thereon, that is
to say :-
On the Sheet of Drawings Figure 1 is a front elevation, Figure 2 a plan, and
Figure 3 a section partly in clevation of the mechanism constituting my said
Invention. The remaining Figures represent certain details which are hercin-after
referred to. The machine, as shown by Figures 1, 2, and 3, consists of a framing A
provided at the top with a table B on which the moving parts are carried. In the
head C which is fixed to the table B by bolts or equivalent means the shaft D is
carried, provided at or about the centre with fast and loose pullies E for driving
it or for stopping it when required, and at its outer ends the cutters F are carried.
The rests are arranged as shown more particularly in the plan Figure 2, that is to
say, the slide G of each rest by which the rest is advanced to or withdrawn from
the cutters F is preferably situated at an angle, as shown at Figure 2, it being
operated inwards or outwards by the screw and hand wheel H. The shaft I is
arranged parallel with but on a lower level than the screw, and it has a groove
in its surface in which a key in the tangent screw J fits so as to slide. By means
of this arrangement as each rest is moved inwards or outwards, that is to say, to or
from the cutters F by the hand wheel and screw H, so is the tangent screw J which
is carried in brackets K descending from the rest correspondingly moved upon the
shaft I. The tangent screw J is always in gear with the worm wheel L on the
lower part of each vertical screw AI of each rest. The screws M engage with the
vertical. sliding tube N of the rests O, so that accordingly as the hand wheels P
which actuate the shafts carrying the tangent screws J are operated so are the
rests which carry the work raised or lowered as required. The construction and
arrangement of the horizontal and vertical slides of the rest, together with the worm
wheel and tangent screw, also the vertical and horizontal screws, are shown more
particularly in the enlarged views of their parts at Figures 6, 7, and S, of which
Figure 6 is a vertical section, Figure 7 a top view of Figure 6, showing portions of
the table B on either side; Figure 8 being a detail of the worm wheel and tangent
screw. The upper portion of each rest, or that marked O, which carries the pieces of
wood or other material on which the screw or spiral moulding has to be cut, is

page_text: provided with a stud at the under side, which fits into the socket at the upper part
of the rest, being securely held therein by the pinching screw R. In the upper part
of each rest the groove or depression S is formed, and into this the cylindrical pieces
of wood or other material upon which the screw or spiral groove is to be cut are
laid, one or more pinching strips T being provided for holding the cylindrical strip
therein, with sufficient steadiness to ensure the cutters producing smooth work
thereon, and yet with sufficient freedom to allow of the cylindrical body both to
rotate and advance horizontally as the cutting progresses.
An opening is made in that side of the rest whereat the cutting takes place, the
object of which is to allow the cutters to be brought into contact with the material
to be operated upon. This opening is seen at U, Figures 9 and 11, which are
enlarged views of the upper portions of the rest. At Figure 12 this part of the rest
is shown with a moveable strip V and set screws W, by means of which the width
of the groove for receiving the cylindrical strips of wood or material to be cut with
screw or spiral grooves can be varied, so that this rest head is capable of being used
for various diameters of cylindrical pieces of material. In the bottom or side of the
groove in this upper part of the rests the comb or projection for catching into the
spiral groove being cut is placed, and whereby the uniform travel of the material
being operated upon and the uniform run of the screw or spiral thread is ensured.
This comb or projection is not, however, essential where deep grooves or threads
are being cut, for the cutter when cutting a deep screw or spiral groove has at
sufficient hold of the cylindrical strip to move it horizontally. On the upper part
of the rest is a stem or bracket carrying the milled wheel o, which is so adjusted in
position on the stem or bracket that it is pressed slightly upon the body p, upon
which the screw or spiral inoulding is or has to be cut. By turning the milled
wheel o either by the hand of the operator or automatically the body p is rotated
as the cutting proceeds.
When it is desired to cut screws or spiral grooves in tapered bodies this is
effected by the use of the rest top, shown in side and end elevation at Figures 13
and 14. In this case the taper or wedge-shaped carrier a is laid in the bottom of
the groove in the upper part of the rest, being preferably provided with a feather
at its under side, which running in a corresponding groove keeps the tapered guide
in position. By this arrangement the upper side of the tapered body on which the
screw or spiral moulding has to be cut is brought horizontal or parallel to the
bottom of the groove in the upper part of the rest, so that a screw or spiral
moulding of uniform depth is cut on the tapered body. If it is desired to cut on or
in a tapered body a screw or spiral moulding of a depth increasing with the
diameter of the tapered body, this may be effected by dispensing with the taper or
wedge-shaped guide herein-before referred to, and placing the tapered body in the
horizontal groove. In all cases when cutting screw or spiral mouldings either on
cylindrical or on tapered bodies the pitch of the screw is regulated by the height
and angle at which the cutters and the cylindrical or tapered bodies to be cut are
brought in contact.
At Figures 4 and 5 is shown in longitudinal section and in end elevation the
apparatus herein-before referred to, as consisting of a sphere capable of eccentric
adjustment relatively with a shaft, for the purpose of starting the cutting of a
screw or spiral groove. This consists of a frame a which is secured to the bed or
table of the machine in such a position that the shaft b can be brought by means of
the adjusting screws in a line with the axis of the body in which the screw or
spiral moulding has to be cut, as it lies in the groove in the upper part of the rest.
The shaft b has a "butterfly centre c at one end, which is engaged with the cylin-
drical strip lying in the groove of the rest, after the ordinary manner of engaging
work with such a centre in a turning lathe. The sphere d is adjusted through
being raised or lowered by means of the screw and nuts e to the requisite degree of
eccentricity in relation to the shaft b. On the shaft is a fixed disc f carrying
screws g; one of these screws after the eccentricity of the sphere has been adjusted
is moved until its point is in contact with that side of the sphere which for the

page_text: time has the shortest radius by virtue of the sphere's eccentric position, so that as
the shaft and disc perform the first half revolution the contact of the set screw g
in the disc with the sphere d causes the shaft and the material with which it is
engaged for being operated upon by the cutter to be advanced forward by an
amount corresponding to the degree of eccentricity, and a screw or spiral cut corre-
sponding to that eccentricity will be produced. This last-named apparatus it is
found necessary to use only in the case of cutting very shallow grooves.
Having now described and particularly ascertained the nature of my said Inven-
tion, and the system, mode, or manner in or under which the same is or may be used
or practically carried into effect, I would observe in conclusion that what I consider
to be novel and original, and therefore claim as the Invention secured to me by the
herein-before in part recited Letters Patent, is-
First. The general arrangement or construction and combination of machinery
constituting the apparatus for cutting screws or spiral mouldings on cylindrical or
tapered bodies, substantially as herein-before described and shown in the annexed
Sheet of Drawings.
Second. The production of screw or spiral mouldings by the operation of re-
volving cutters of any required shape or profile acting upon and cutting into the
bodies on which the screw.or spiral mouldings are to be produced, and in such
manner that the action of the cutters is not only to form the screws or spiral
mouldings, but at the same time causes the rotation and travel or advance of the
bodies on which the spiral screws or mouldings have to be cut, and without the use
of pattern screws, substantially as herein-before described.
Third. The arrangement and construction of the adjustable rest, and especially
the upper member thereof, formed with a groove for carrying the body on which
the screw or spiral moulding is or has to be cut, and with or without a comb or
projection for entering the screw or spiral groove, and guiding its rate of travel,
substantially as herein-before described and shown under different arrangements on
the annexed Sheet of Drawings.
Fourth. The apparatus shown at Figures 4 and 5 of the annexed Sheet of
Drawings for starting the cutting-off screw or spiral mouldings, substantially as
herein-before described.
In witness whereof, I, the said Robert Henry, have hereunto set my hand and
seal, this Fourth day of January, One thousand eight hundred and seventy-
ROBERT HENRY. (L.S.)