IMPROVE- MENTS IN MACHINES FOR CUTTING SCREWS
Year: 1872

page_text: LETTERS PATENT to William Edward Laycock, of Portobello Place,
Sheffield, in the County of York, for the Invention of "IMPROVE-
MENTS IN MACHINES FOR CUTTING SCREWS."-A communication from
abroad by James M. Carpenter, of Pawtucket, in the State of
Rhode Island. in the United States of America.
PROVISIONAL SPECIFICATION left by the said William Edward Laycock
at the Office of the Commissioners of Patents, with his Petition, on
the 31st October 1872.
↑
I, WILLIAM EDWARD LAYCOCK, of Portobello Place, Sheffield, in the
County of York, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN MACHINES FOR CUTTING SCREWS," a communication
to me from abroad by James M. Carpenter, of Pawtucket, in the State
of Rhode Island, in the United States of America, to be as follows:-
This Invention relates to the construction of screw-cutting machines
for forming the thread on lag or coach screws, or other screws which are
screwed into wood, by means of which a conical threaded point, known

page_text: as the "gimlet point," may be formed thereon, and it consists in com-
bining with the dies which cut the body of the screw made in any of
the well-known forms, one or more tools or chasers placed at the back
side of the dies, and having a motion towards and from the axis of the
screw and working in suitable guides to form a tapering thread at the
point of the screw; also in forming the conical part of the trumpet-
mouthed dies with a series of cutting threads, in combination with one
or more holding threads not made with cutting edges, by which the
screw is firmly held while its point is operated upon by the pointing
tools; also in combining with such dies a leader that will act with the
dies while the blank is entering them, and then be disengaged to allow
the dies to form the screw and to be removed therefrom in the usual
manner, by means whereof a perfect junction of the point with the
body is effected; also in combining with the dies that cut the body of
the screw, or the equivalent thereof, two tool holders and tools, and the
guiding patterns or formers for the same, for cutting the screw on the
point, one of which tools partially cuts the point in running the dies
on to the blank, and the other of which finishes the point when the
dies are backed off; also in cutting the gimlet point upon the screw
by an operation subsequent to that by which the thread is cut upon
the body, so that the strain of the two operations shall not come upon
the screw blank at the same time, while the screw threads upon each
part of the screw shall be made accurately to coincide, this is accom-
plished by a threaded back rest formed like the segment of a nut, which
holds the screw after the dies which cut the body have left it; com-
bined with the pointing tool or tools by which the thread is cut
upon the point while the screw is supported by the threaded rest; also
in the use of a serial cutter or tool which is made with a series of cutting
edges, which are set in a line nearly coinciding with the inclination of
the point of the screw, and which controls its radial movement in such
wise that the several cutting edges will remove successive shavings
from the point of the blank; also in the combination of a threaded
back rest to support the screw, which serves as a leader in the operation
of forming the threads upon the point and the series of cutting
points or teeth, which are moved radially under the control of a
pattern or former, by which means screws may have gimlet points
formed upon them, the bodies of which have been cut by a separate
operation.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Edward Laycock in the Great Seal Patent
Office on the 29th April 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
EDWARD LAYCOCK, of Portobello Place, Sheffield, in the County of York,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirty-first day of October, in the year
of our Lord One thousand eight hundred and seventy-two, in the thirty.
sixth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said William Edward Laycock, Her special
licence that I, the said William Edward Laycock, my executors, adminis-
trators, and assigns, or such others as I, the said William Edward
Laycock, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "IM-
PROVEMENTS IN MACHINES FOR CUTTING SCREWS," being a communication to
me from abroad by James M. Carpenter, of Pawtucket, in the State of
Rhode Island, in the United States of America, upon the condition
(amongst others) that I the said William Edward Laycock, my executors
or administrators, by an instrument in writing under my, or their, or one
of their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that I, the said William Edward Laycock, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement (that is to say) :-
This Invention relates to the construction of screw cutting machines
for forming the thread on lag or coach screws, or other screws which are
screwed into wood, by means of which a conical threaded point known
as the "gimlet point" is, or may be formed thereon, and it consists in

page_text: screw,
combining with the dies which cut the body of the screw made in any
of the well-known forms, one or more tools or chasers placed at the back
side of the dies, and having a motion towards and from the axis of the
screw, and working in suitable guides to form a tapering thread at the
point of the screw, also in forming the conical part of the trumpet
mouthed dies with a series of cutting threads, in combination with one
or more holding threads, not made with cutting edges, by which the
screw is firmly held while its point is operated upon by the pointing
tools; also, in combining with such dies a leader that will act with the
dies while the blank is entering them, and then be disengaged to allow
the dies to form the screw, and to be removed therefrom in the usual
manner, by means whereof a perfect junction of the point with the body
is effected; also in combining with the dies that cut the body of the
or the equivalent thereof, two tool holders and tools, and the
guiding patterns or formers for the same for cutting the screw on the
point, one of which tools partially cuts the point in running the dies on
to the blank, and the other of which finishes the point when the dies are
backed off; also in cutting the gimlet point upon the screw by an
operation subsequent to that by which the thread is cut upon the body,
so that the strain of the two operations shall not come upon the screw
blank at the same time, while the screw threads upon each part of the
screw shall be made accurately to coincide; this is accomplished by a
threaded back rest formed like the segment of a nut, which holds the
screw after the dies which cut the body have left it, combined with the
pointing tool or tools by which the thread is cut' upon the point, while
the screw is supported by the threaded rest; also, in the use of a serial
cutter or tool which is made with a series of cutting edges which are set
in a line nearly coinciding with the inclination of the point of the screw
and which controls its radial movement in such wise that the several
cutting edges will remove successive shavings from the point of the
blank; also in the combination of a threaded back rest to support the
screw which serves as a leader in the operation of forming the threads
upon the point, and the series of cutting points or teeth which are
moved radially under the control of a pattern or former, by which means
screws may have gimlet points formed upon them, the bodies of which
have been cut by a separate operation.
And in order that the Invention may be fully understood, and readily
carried into operation, I will proceed to describe the accompanying Sheet

page_text: Fig. 1 is a plan of the improved screw cutting machine; Fig. 2 is a
vertical longitudinal section; Fig. 3 is a sectional elevation of the back
side of the die stock; Fig. 4 is a front elevation of the cam ring
detached; Fig. 5 is a view of the point of a screw blank before cutting
the thread upon it; and Fig. 6 is a view of the finished gimlet point.
a is the frame or bed of the machine, and 6 is a revolving mandril
supported therein in suitable bearings b', upon the inner end of which
is mounted the die stock c which carries the dies d, for cutting the
cylindrical portion of the screw thread. There is a circular aperture in
the centre of the stock behind the dies which extends through to the
back side of the stock, and into the boss of the same a sufficient distance
to receive the longest screw to be made. In the back side of the stock
are two radial dovetailed recesses e, e, for cutting the thread upon the
point of the screw, which slide in the said recesses toward and from the
centre to give the requisite taper to the thread by means of the diagonal
slides or cams f, shewn more clearly in Fig. 2. The slides fare attached
to the cam ring g at one end, and at the other end they work through
guides attached to the die stock. The intermediate portions of the
slides are made diagonal to the axis of the mandril, and work through
mortises in the cutters e, so that when the cam ring g is slid along
longitudinally on its bearing, carrying the several slides with it, the
slides move the cutters e radially towards and from the axis under
perfect control. The cam ring g is fitted upon the boss c¹ of the die
stock, as shewn, and the boss is made with openings into the central
cavity through which the cutters e work. In the periphery of the cam
ring g, is formed a groove i, in which the forked lever j works, by means
of which the ring g is moved toward and from the die stock c to move
the cutters e in or out. The lever j has its fulcrum at j¹, and at its
outer end is a pin k, which works in the long notch 7 formed in the sliding
bar m.
The bar m is attached at one end to the arm n, which is carried
upon the holder o, by which the screw is held while being cut. The
opposite end of the bar m works through a mortise in the bracket p,
which is attached to the frame of the machine. The holder o is mounted
in the standards o', so as to be free to slide lengthwise, but not to revolve,
and it is provided at its inner end with a socket to receive the head of
the screw, and hold it from revolving. It is intended to be moved back
and forth by the hand except when moved by the screw thread which
is formed to bring the screw up to the dies, or to remove the screw and'

page_text: insert a fresh blank. The end of the bar m near the bracket P is made
with an inclined part q, as shewn, which works through the mortise in
the bracket p, and when the bar is moved in that direction, so that the
inclined part has passed through the mortise, it has the effect to move
that end of the bar laterally, so far outward that the notch is removed
from the pink, which leaves the lever j at rest, although the movement
of the bar continues. When the movement of the bar m is reversed
the action of the incline a causes the notch to again engage with the
pink, and move the cam ring back, and withdraw the slides f which
move the cutters e inward to the centre. In this condition of the parts
the holder can be drawn back a sufficient distance to enable the screw
to be removed therefrom and a fresh blank inserted clear of the dies.
The points of the cutters are made of the proper form to give the
desired form to the thread, and to correspond to the form of the thread
produced by the dies upon the body of the screw, and they are also
set to correspond to the position they would occupy respectively in the
thread in forming the conical point, as is shewn in Fig. 6, and although
I have shewn in the Drawing only two cutters placed opposite each
other, in cutting coarse threads where considerable metal has to be
removed, I propose to use three or four, set radially around the circum-
ference to divide the labour among a greater number of cuts. In cutting
screws with this machine the blanks are first pointed by a separate
machine in the manner usually employed in the manufacture of wood
screws, as is shewn in Fig. 5. The holder o being drawn back the head
of the screw is placed in the socket and the holder is carried forward
until the point of the blank is inserted in the dies. By the revolution
of the dies the screw is cut upon the body of the blank, at the same
time drawing the holder forward and with it the bar m.
The position
of the notch Z is so adjusted in relation to the dies that when the
shoulder of the notch comes in contact with the pin k, the point of
the blank will have reached the cutters e, and commenced to cut the
thread upon the point. By the progressive motion of the screw holder
and bar m the cam ring will be carried forward through the intervention
of the lever j, and by means of the slides f will withdraw the cutters e
just fast enough to give the conical form to the screw thread, each
cutter removing a portion of the metal and passing into the thread
formed by the dies. By the time this is done the inclined part q of the
bar m will have passed nearly through the mortise in the bracket p, and
carried the shoulder of the notch off from the pin k, which will leave
3

page_text: "
the lever j at rest while the dies continue their operation until the thread
is completed. The motion of the mandril and dies is then reversed to
back the dies off from the screws, and the holder o and bar m is moved
back when the incline q carries the notch on to the pin k, and the
shoulder m carries the lever i backward until the screw is out of the
j
dies. The holder o is then drawn back by hand to remove the screw,
and also to carry the cam ring g back, and place the cutters e in position
to cut another screw.
Although I have shewn a machine in which the dies are made to
revolve to cut the thread while the blank is held, it is obvious that the
same mode of operation could be employed if the dies were made stationary
and the screw blank was rotated, and many other arrangements of parts
could be used to control the motion of the cutters e, and any other
form of dies operating in the usual way could be used for outting the
body of the screw instead of those shewn.
Fig. 7 is a plan of another of the improved machines for cutting
screws; Fig. 8 is a vertical longitudinal section; Fig. 9 is a transverse
section of the same, and Figs. 10 and 11 are full sized views of the
improved dies.
A is the bed of the machine, and A' the headstock that carries the
mandril B, which turns the screw blank B', and is driven in both directions
in any of the modes usually practiced in screw cutting machines; C is a
frame or bed which slides on ways on the bed A, and is secured thereto
in any usual way to adapt the machine to the length of the screw to be
made. Upon this frame the carriage D slides lengthwise in suitable
guides, which carries the die stock E', and the pointing tools F and F³,
and their tool holders G and G', as is shewn. The carriage D is moved
forward and back by hand by the rack H and pinion P upon the shaft
of the hand wheel j, which revolves in bearings in the bed C, for the
purpose of removing the finished screw, and introducing a fresh blank.
The dies E are of a peculiar construction to meet a condition of things
that has been stated, and are shewn in full size in Figs. 10 and 11.
They are made trumpet-mouthed, as shewn, and also made with four
series of cutting edges a, a, a, which cut away the material between
the threads of the screw, and bring it to the proper size, but the.
threads b, b, are not made with cutting edges, but are smooth and of
such internal diameter that the screw formed by the cutting part of the
dics will enter them with sufficient compression to hold the rerew firm

page_text: so as to sustain the strain of the pointing tools without yielding, which
otherwise might spoil the gimlet point of the screw. These dies may be
held in the die stock E' in any usual way. The two tool holders G, G¹,,
are attached to the carriage D, and swing upon the bolt G. Their ends
next to the dies are provided with seats for holding the pointing
tools F, F', by means of the clamp f, f, and screws g, g; G³, G³, are
arms extending outward upon the tool holders G and G¹, which carry
guide pins K, K', which work in the pattern or guide grooves L, L',
formed in the pieces, M., M', respectively, which are secured to the top
of the frame C. One of the grooves L is provided with a swinging
directing picce M², which when the carriage D is run back is moved to
the position shewn by the dotted lines, and directs the guide pin K into
the inner part of the grooves L, and the other groove L has a sliding
piece M³, which slides back to the position shewn by the dotted lines,
and directs the guide pin K' into the outer part of the guide groove.
These movements of the tool holders are also assisted by the springs d, d²,
which are attached to the tool holders respectively as shewn, and press
them both towards the front of the machine. N is the leader which has
the pitch of the screw to correspond with that of the screw to be cut,
and also has its thread made vertical on its working face, and in this
thread a slide O works, which slide up and down in the die stock, and is
a substitute for a nut. The leader N is made so as to be adjusted upon
the shaft N' to accomodate the length of the screw to be cut, and is
driven by spur gearing n, n³, from the mandril. From the back side of
the slide O a pin o projects and works in the groove p, see Figs. 8 and 9,
by which the slide O is engaged with and disengaged from the leader
when the pin o passes through the inclined part of the groove P, as
shewn by the dotted lines in Fig. 8, which raises and lowers the slide.
The operation of the machine is as follows:-The carriage D carrying
the die stock and tool holders is run back by the hand wheel J, and the
blank previously pointed is placed in the socket of the mandril B. The
carriage is then brought up by the hand wheel until the pin o enters
the inclined part of its groove p, which lowers the slide O, so that its
lower end engages with the screw thread on the leader N, and carries
the carriage D and its attachments along until the dies have passed on
to the point of the blank. The engagement of the slide O with the
leader takes place just before the point of the screw comes in contact
with the dies. After the dies are fully engaged with the blank, the

page_text: slide O passes. off from the end of the leader, and the forward motion of
the carriage D is then produced by the screw blank and dies. When a
sufficient length of screw is cut the motion of the mandril B is reversed,
and the carriage is thereby carried back and the slide O enters the screw
of the leader, which continues the movement of the carriage until the
dies have passed off from the point of the screw, and the incline of
the groove p has raised the slide O out of the threads of the leader when
the carriage is free to be moved back by hand and is ready to repeat the
operation. The motion of the mandril B in running backward is about
three times as fast as when running forward to cut the screw, and
the pointing tool F¹, which finishes the point when running off, is set
so as to take lighter cuts or shavings than the other tool, so as to
favor the increased weakness of the point and give a neater finish to
the screw.
Fig. 12 is a plan of another of my improved machines for cutting
screws; Fig. 13, is a side elevation of the same; Fig. 14 is a transverse
sectional elevation, showing the threaded rest and the pointing tool;
Fig. 15 is a sectional elevation looking towards the side of the machine
that carries the pointing tool; Fig. 16 is a sectional elevation looking in
the opposite direction; Fig. 17 is an enlarged section of the serial
pointing tool; Figs. 18, 19, and 20, represent a modified form of my
improvements for forming gimlet points on screws, the bodies of which
have been previously cut.
A represents the frame or bed upon which the other parts of the
apparatus are arranged, as shewn, which rests upon and is secured to the
ways of a common lathe bed, or any other suitable frame. B, represents
the position of the mandril for turning the screw to be cut, which is
made in the usual way. The bed A is provided with ways a, a, in
which the carriage C slides back and forth to which the die stock D is
attached. The die stock D carries the dies D¹ for cutting the body
of the screw, and also has attached to it two horizontal dovetailed
slides b, b, on opposite sides of the centre, upon which the two
stocks E, F, slide towards and from the centre. To one of the stocks E,
the tool holder E' is attached, which carries the serial tool e, which cuts
the thread upon the point of the screw. To the other slide F is
attached the threaded rest F which holds the screw while the thread is
being cut upon its point. To these stocks E, F, respectively are
attached studs and g, which work in the guide or pattern grooves of

page_text: the pieces G and H, and which move the stocks E, F, toward and from
the centre as will be described hereafter. The form of the serial tool e,
is shewn in section enlarged in Fig. 17, and is sharpened by grinding off
the end. It is held and adjusted in the tool holder E' by the clamp c
and set screw d as shewn. The rest F¹ is formed like half of a nut,
and has a screw thread made in it of a shape to fit the thread upon the
body of the screw. While the dies D¹ are running on to the blank to
cut the screw upon the body the studs ƒ and g of the slides run in the
outer grooves f¹ and g¹ of the pieces G and H, but when the motion
of the screw is reversed, to back the dies off from the screw, the studs
are made to enter the inclined parts and g³ by the action of the
springs hand k, which move both of the stocks E and F, inward by
the act of moving the carriage C and its connections backward. The
positions of the inclined parts of the groove f2 and 92 are such as to
move the stocks E and F respectively, so that the threaded rest F¹ will
come up against the body of the screw, and at the same time the tool e
will come up to the screw, so that its most prominent point or tooth will
be nearly in contact with the bottom of the thread just before the
dies D¹ leave the screw. After the dies D¹ leave the screw the backward
motion of the carriage C is continued by the action of the rest F, and at
the same time the stud fenters the inclined part of its groove, which
is of the proper inclination to carry the serial hook e over the point of the
screw to cut the thread thereon by a succession of shavings, and also to
hold the screw firmly in the back rest. The further.backward movement
of the carriage C is produced by the hand wheel K and rack I, and
pinion J, and by this motion the studs ƒ and g pass outward through
the inclined grooves f³ and g³ to the outer grooves f¹ and g', which
draw back the stocks E and F respectively, and permit the finished
screw to be removed and a fresh blank to be supplied. The carriage C
with the dies are then brought up to and entered upon the screw, and
the operation is repeated. While the carriage is moving forward the
studs and are retained in the outer grooves, and as they move
forward push aside the springs h and k, which on the return of the
studs direct them into the inclined parts of their respective grooves, as
has been stated. The velocity of revolution of the screw in running the
dies back is very much greater than when cutting the screw upon the
body, both for the purpose of saving time, and also that the thread upon
the point is better formed when it is running at a velocity proper for
cutting the body of the screw with the dies. In using the serial tool.

page_text: I propose in some cases to make the longest point or bit separate, as
shewn in dotted lines at L in Fig. 17, and to use this only for the
purpose of holding the screw into the threaded rest F¹, and is not
intended to cut, and is therefore made separate from the tool which has
to be ground upon the end to form the, cutting edges. But this part
may also be formed upon the tool and ground with the rest, and then
slightly blunted to prevent it from cutting, which will operate in the
same way.
'
In Figs. 18, 19, and 20 are represented a part of my improvements.
adapted to forming gimlet points upon screws already cut, in which A
is the frame; B, the mandril for turning the screw; C, the carriage
sliding in guides in the frame A as before; E¹ is the threaded rest,
which is fixed to the carriage C, and E is a lever which has its fulcrum
at E upon the carriage, and carries the tool holder E¹ attached to it, as,
shewn. The serial tool e is held in it by the clamp c and set screw d,
as before described. The lever E has a handle L by which it is worked,
as well as the carriage C, by the attendant. The outer end of the lever
is turned down and carries a pin f, which works in the guide groove f¹
of the former H, which is attached to the bed by screws, as is shewn
more clearly in Figs. 18, 19, and 20. The form of the inclined part of
the groove at f2, Fig. 20, is such as to bring down the lever with the
proper motion to carry the tool down the inclination of the point of
the screw and cause the several points of the tool to cut away the
metal in successive shavings to form the thread, while the tool and
carriage are carried longitudinally by the action of the threaded rest F¹,
in connection with the screw threads upon the body of the screw, as in
the other form of my improvements.
In cutting screws by my improvements the operation with the
mechanism described in reference to Figs. 12 to 18, is as follows:-The
screw blank previously pointed is secured in the socket B, and the
dics are brought up to and started on to the same, and the screw is cut
upon the body of the blank by the usual mode of operation to as great a
length as desired. The motion of the mandril is then reversed and run
back with a motion, say, three times as fast as the motion in cutting
the screw. When the dies have nearly reached the end the threaded
rest F is brought up to the screw so as to engage accurately with the
screw threads already formed, and the pointing tool with its series of
points is brought up to the opposite side of the screw, which holds it
C

page_text: into the rest and causes it to push the carriage back after the dies have
left the point of the screw. By this last part of the motion the tool
by its pattern groove f is directed so as to cut the threads upon the
point, as has been already described. After the tool has passed off
from the point of the screw the studs fand g pass through the inclines
g3 and f, which draw back the stocks E and F, with the tool and
rest F, when the finished screw is removed and a fresh blank is supplied
to repeat the operation.
In pointing screws by the modification last described the operation
is as follows-The carriage C is drawn towards the mandril B, so that
when the screw is inserted in the socket of the mandril its body will lay
in the threaded rest F¹. The lever E with the tool e is then brought
down upon it until the stud frests upon the bottom of the groove f¹,
the mandril is then put in revolution in a backward direction, which
by the threaded rest pushes the carriage outward and with it the tool.
As the stud passes .down the incline f of the piece H, Fig. 20, it
guides the tool over the point and forms the thread upon it, as has
already been described, by pushing the carriage further in the outward
direction the stud f passes up the incline f' and raises the lever, so that
the screw can be readily removed.
Having thus stated the nature and particulars of the Invention
communicated to me by the within-named James M. Carpenter, I
declare that I claim,-
First. The combination of one or more cutters for forming a tapering
thread on the point of the screw with the dies for forming the thread
upon the body, substantially as described and shewn in Figs. 1 to 6
inclusive.
Secondly. The method of forming trumpet-mouthed dies for cutting
screws, with a combination of cutting and holding threads, substantially
as described and shewn in Figs. 7 to 11 inclusive.
Thirdly. The combination of trumpet-mouthed dies with a leader
operating as described to cause the screw blank to enter the dies
properly and to be disengaged from the leader. when the dies have fully
engaged with the blank, substantially as described.
Fourthly. The combination of the dies for cutting the body of the
screw with two pointing tools and two patterns or formers to guide
the same, so arranged that one of the said tools shall act when the

page_text: screw blank is running into the dies, and the other when the screw is
running out, substantially as described.
Fifthly. The threaded rest as a device to support the screw already
formed while being operated upon by the pointing or other tools, and
in connection with the screw to act as a leader to give motion to the
tool carrier, substantially as described and shewn in Figs. 12 to 20
inclusive.
Sixthly. The serial tool e in combination with a former or guide, so
related thereto that as the tool is carried past the point of the blank the
several teeth will cut successive shavings therefrom and complete the
thread, substantially as described.
Seventhly. The combination of the threaded rest and pointing tool,
substantially as described.
And, lastly. The combination of the threaded rest and the pointing
tool or tools with the dies for cutting the body of the screw, substantially
as described.
In witness whereof, I, the said William Edward Laycock, have
hereto set my hand and seal, this Twenty-sixth day of April,
One thousand eight hundred and seventy-three.