Improvements in Knotters for Sewing Machines.
Year: 1894

page_text: Date of Application, 22nd Oct., 1894
Complete Specification Left, 6th July, 1895-Accepted, 10th Aug., 1895
PROVISIONAL SPECIFICATION.
Improvements in Knotters for Sewing Machines.
I, ALFRED WELLBORN COCHRAN of No. 726 Broadway in the City of New York,
in the County and State of New York, United States of America, Clerk, do hereby
declare the nature of this invention to be as follows:-
This invention is designed for use in tying the threads together in a two thread
sewing machine and is especially intended for tying such threads together at the end of
the line of sewing, or at any desired intermediate points. The sewing mechanism
is of any desired character, such for instance as a reciprocating eye pointed needle
passing through holes in a throat plate, and a shuttle thread is passed through the
loop of needle thread so that the threads are interlocked at the fabric.
The twister is composed of a circular piece of wire passing into a hole or
opening in the bed and beneath the surface thereof, and upon the end of this
twister is a head by which the twister can be given a complete rotation, and one
side of this head is removed so as not to interfere with the passage of the goods
that are being sewn over the bed of the sewing machine.
At the end of the twister is a hook adapted to catch the shuttle thread that
extends up from below through the holes in the throat plate, and upon the twister
is a pin in a diagonal slot and a spring to project the twister to its uormal position,
and the parts are so constructed that as the twister is rotated, the pin in the
diagonal slot gives motion to the twister end wise and causes the hook to draw the
shuttle thread along and twist such thread into the form of an open loop and hold
such loop in a position for the eye pointed needle to pass down through such loop,
causing a loop of needle thread to be put through this twisted loop, and then the
shuttle thread by the ordinary sewing operation is put through the loop from the
eye pointed needle, and as the parts draw up a complete knot is tied beneath
the fabric, and the two threads can be cut off as usual.
In some instances a single rigid hook is used at the end of the twister and it
carries the loop of shuttle thread around the lower eye in the throat plate and
spreads such loop of shuttle thread; in other instances I make use of a twister
with one side rigid and having the hook upon it and the other side made as a spring
with a hook upon it, and when this form of twister is made use of, the end move-
ment given to the twister, as before set forth, causes the spring part of the twister
to close against the rigid part and catch the shuttle thread and give to it the
necessary twist to form the loop as the twister is rotated, and as the said twister
moves longitudinally by the action of the spring and of the pin in the inclined slot,
the twisted loop is opened or spread by the spring side of the twister, so as to
hold such loop in the proper position for the passage through the same of the eye
pointed needle in taking the last stitch before the threads are drawn up and the
knot tied. These parts can be made in the bed of a sewing machine or be upon
a movable plate connected with the sewing machine and having the eyes or throat
through which the eye pointed needle passes.
Dated this 22nd day of October 1894.

page_text: Improvements in Knotters for Sewing Machines.
I, ALFRED WELLBORN COCHRAN, of No. 726 Broadway, in the City of
New York, in the County and State of New York, United States of America,
Clerk, 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 :-
I construct the twister with jaws, the exterior surfaces of which when the jaws
are closed form a cylinder between the upper and lower parts of the throat plate,
and by the act of rotating the twister the spring-jaw is closed against the rigid jaw
around the thread, by the pressure of said spring-jaw against one wall of the
opening in the throat-plate, and a cam-slot and pin are provided for drawing back
the jaws after they have been closed to seize the thread, in order that the parts of
the loop may interlock at the end of the twister, and then the twister is moved
forward again and opens into the slot provided for that purpose and the spring jaw
spreads. the twisted loop for the passage of the needle, after which the shuttle is
passed through the loop of needle thread and the twisted 'loop of shuttle thread
draws off the twister and is around the needle and draws up closely against the under
surface of the fabric that is being sewed as the needle rises and the knot is
tightened at this place as the threads are drawn up in the usual way in tightening
the stitch.
In the drawings,
Figure 1, is a plan view partially in section, representing the throat plate and
twister.
Fig. 2 is a side view of the parts, also partially in section.
Fig. 3 is a perspective view showing the twister as detached from the throat
plate and open to release the loop, and Fig. 4 shows the twister as closed and
revolved half way around.
Fig. 5. is a diagram of the knot.
Fig. 6 is a cross section, at the 'line a x, Fig.1, and Fig. 7 is an elevation of the
button head of the twister.
Fig. 8 is a perspective view of a portion of the throat plate.
The throat-plate A, is preferably formed of a piece of metal sufficiently thick
for a bole to be bored therein longitudinally and parallel with its upper and lower
surfaces and an opening extends from this hole laterally to the edge of the plate
thereby forming an upper plate 2, and a lower plate 3, which are perforated with
holes for the passage of the needle, and the twister B is formed of substantially a
cylindrical wire filling the hole in the throat plate and having a button or head C
at the outer end, and this button or head C is advantageously circular except that
the upper part thereof should be cut off at the same level as the top surface of the
throat plate so as not to interfere with the fabric that is being sewed as the same
lies upon the surface of the threat plate, and by providing a notch at 4 in the end
of the head, the twister may be rotated by inserting the nail in the notch 4,
pressing the twister inwardly against the action of the helical spring D that
surrounds the outer part of the twister shank, and in so doing the circular portion
of the head C is brought above the surface of the sewing machine table and can be
rotated by pressure of the finger, so that it revolves once in twisting the thread, as
hereinafter described.
The throat plate (A) may be secured to the bed of the sewing machine in any
convenient nanner. Usually it is attached to the plate (A¹) that is screwed to the
hed of the sewing machine and has the openings for the feed bar as usual.
Across the projecting end of the throat plate is a diagonal slot or mortise at 5

page_text: 0
within which is a pin 6 upon the shank of the twister; and it will be observed that
his pin 6 as the twister is rotated and the pin travels in the slot 5 gives to the
wister an end movement hodily and then forces the twister back again into its
normal position, and by providing an off-set or notch in the slot 5, as at 7, the
twister is stopped each rotation in the proper position by the pin 6 passing into
said notch or offset at the completion of the rotation, and the twister has to be
pushed inwardly against the action of the spring D before the pin 6 will clear the
offset 7 and hence before the twister can receive its rotation. This insures the
inward movement which is advantageously given to the twister in the act of
grasping the thread. Through the upper and lower sides 2 and 3 of the throat
plate there are the holes 8 and 9 for the eye-pointed needle to pass through, and
these are in such a position that the jaws of the twister are at opposite sides of the
needle as it passes through the holes; and it is to be understood that this throat-
plate is secured to the sewing machine but with the upper surface of the throat
plate on the level or nearly so of the sewing machine bed and hence that the
shuttle thread passes up through the holes 8 and 9 as the lock stitch is drawn up
or tightened in the fabric, and that the twister is to be actuated only when the
needle is out of the cloth, and hence the twister acts upon the lower or shuttle
thread as it draws through the holes 8 and 9.
The peculiarity of the jaws of the twister will be most clearly seen in the detached
perspective view Fig. 3. The body of the twister is slotted longitudinally to form
the two jaws. One side is reduced so that the portion 10 forms a spring that tends
to open the jaw end of the twister, and the exterior surfaces of the jaw ends of the
twister are semi-cylindrical, and the opposite adjacent faces of the jaw ends are
recessed so that when the jaw ends are brought together as in Fig. 4, there is an
elongated mortise for the thread, and in the rigid side of the jaw is a groove 12
running outwardly from the mortise. The spring jaw usually is not provided with
a hook to avoid entangling the thread but it is inade slightly thinner in order to
leave room for the passage of the thread during the rotation, the loop is thus
released entirely from the under jaw and assumes the position shown in Fig. 3;
and it will also be observed by Fig. 6 that the lower eye or hole 9 through the
lower side 3 of the throat plate is elongated and its edge rounded, the object being
to prevent clamping and cutting the thread when the parts are rotated in twisting
the shuttle thread. It is now to be understood that when an end motion is given to
the twister, as before described, it passes toward the shuttle thread as the same
extends through the two eyes or holes 8 and 9 of the throat plate, and as the
twister is rotated the spring jaw thereof is closed by the semi-cylindrical surface
upper and
thereof sliding on the lower plate as the twister is rotated between the
lower sides of the throat plate, and the twister is closed so that the thread is withiṇ
the elongated slot of the twister. In this position the ends of the mortise through
the twister extend nearly as far as the edges of the eyes 8 and 9, so that the thread
cannot be caught between the surfaces that come together but is free within the
mortise, and as the rotation proceeds the twister is also drawn back by the action
of the diagonal slot and pin and the thread is slipped off the looper as it draws back
by coming into contact with the termination of the opening into which the spring
jaw expands, and the thread is thus directed into the groove of the rigid jaw and
prevented from wrapping around said jaw and the proper interlocking takes place
at the ends of the jaws. The parts are formed so that the end of the rigid jaw
disappears before its forward movement begins. The thread having assumed its
proper position in the groove stays there during the remainder of the rotation.
spring jaw is made slightly the longest in order to secure a greater expansion
of the loop which takes place by reason of the increased circumference traversed by
the thread in wrapping around the elongated jaw and the two parts of the thread
twist together and interlock at and beyond the end of the twister before the rotation
is completed, and as the twister is forced back again to its normal position and the
spring jaw of the twister opens, the twisted loop of thread is spread, as illustrated
in Fig. 3, for the eye-pointed needle to pass through such loop. The interlocking

page_text: parts of the thread are beyond the ends of the twister and below one edge of the
hole 8, and out of the way of the descending needle, and the portion of the loop of
thread that passes across from one jaw to the other is near the other edge of the
hole 8, so that the needle passes freely through the loop. The loop of needle thread
is passed around the shuttle or the shuttle passed through the loop, as illustrated in
Fig. 5, so that the twisted loop of shuttle thread draws off the twister by the
tension and is around such eye-pointed needle and is shed off the needle against the
under side of the fabric that is being sewed as the needle draws up and the needle
thread is drawn up, by the action of its tension, through the twisted loop of shuttle
thread until the threads tighten and a knot similar to a sailor's knot is tied closely.
adjacent to the under side of the fabric that is being sewed.
"It will be observed that the metal of the throat plate keeps the spring side of
the twister closed up against the rigid side of the twister when the parts have been
half rotated, as indicated in Fig. 4, and the parts of the jaws of the twister are in
such a position that the thread passes out of the mortise of the twister and the
parts of the thread are held by the jaws, and when the twister has been revolved
half way the twister bas been drawn back by the pin and inclined slot so that the
ends of the twister are back from the holes 8 and 9, and the threads are obliged
to twist together beyond the ends of the jaws as in Fig. 4, and as the twister
completes its rotation it is moved forward into the position shown in Fig. 1, and
the loop of thread is spread as indicated in Fig. 3, and the interlocking portions of
the thread are beyond the open ends of the twister jaws and the twisted loop is
easily drawn clear from the spring twister jaws, in consequence of the movement
of the shuttle after the needle has passed through the twisted loop, because the
part of the twisted loop that is spread by the spring jaw is free to pass off from
the spring jaw, and the other part of the twisted loop between the rigid jaw aud
the throat plate is only held with a slight friction and the thread pulls out from
that position by the friction of the twisted loop around the eye-pointed needle as
such eye-pointed needle rises and the loop is cast off from the spring jaw. The
knot is completed as the threads are tightened as aforesaid.
By constructing the parts in the manner before described the operations are
rendered perfect and reliable and the end movement of the twister is rendered as
short as possible and the angle of the cam slot is such that the pin can be easily
moved therein with but little friction. The ends of the jaws when closed being
cylindrical and filling the space between the upper and lower sides prevent the
thread slipping out from the mortise and the thread draws over the ends of the
jaws as they open and the loop is spread.;
In some characters of sewing machines the cover plates over the shuttle raceway
will come up at each side of the extending portion of the throat plate and also
partially adjacent to the plate A', as illustrated at E F, Fig. 1.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what 1
claim is :-
First The combination with the throat plate, with an opening for the passage
of the eye-pointed needle and a longitudinal hole, of a rotatable twister within
such hole having one rigid and one spring jaw, the exterior of the spring jaw being
rounding so as to be closed in its rotation by contact with the throat plate, the jaws
being recessed in their inner faces to form an elongated eye and grooved for
twisting the thread, substantially as specified.
Second-The combination with the throat plate having upper and lower sides
with openings for the passage of the eye-pointed needle and a longitudinal hole, of
a rotatable twister within such hole having one rigid and one spring jaw, the
exterior of the spring jaw being rounding so as to be closed in its rotation by
contact with the throat plate, the jaws being recessed in their inner faces to form
an elongated eye and grooved for twisting the thread, and means for giving an end
movement to the twister as it is rotated, substantially as specified.

page_text: Third-The combination with the throat plate, of a twister formed of a
cylindrical wire split longitudinally and having a spring jaw and grooved,.
mechanism for giving an end movement of the twister as the same is rotated, a
circular head upon the end of the twister with the upper edge removed to the level
of the top of the throat plate, and a notch for receiving the finger nail for rotating
such twister, substantially as set forth.
Fourth-The combination with the throat plate having upper and lower sides,.
with openings for the passage of the eye-pointed needle, a diagonal slot and a
longitudinal hole, of a rotatable twister within such hole having one rigid and one
spring jaw, the exterior of the spring jaw being rounding so as to be closed in its
rotation by contact with the throat plate, the jaws being recessed in their inner
faces to form an elongated eye and grooved for twisting the thread, and a pin on
the shank of the twister within said diagonal slot, the latter having also an offset.
or shoulder to form a stop for the pin, substantially as specified.
Dianed by me this 18th day of June 1895.
ALFRED WELLBORN COCHRAN
Witnesses:
CHAS. H. SMITH,
140 Nassau Street, New York.
J. STAIB,
140 Nassau Street, New York.