Improvements in Thread-cutters for Sewing Machines.
Year: 1894

page_text: Date of Application, 28th Aug.. 1894-Accepted, 13th Oct., 1894
COMPLETE SPECIFICATION.
Improvements in Thread-cutters for Sewing Machines.
1, JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex,
Gentleman, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by The Willcox & Gibbs Sewing Machine
Company of New York City, in the United States of America, a Company
incorporated under the laws of the State of New York) and in what manner the
same is to be performed to be particularly described and ascertained in and by the
following statement :-
This invention has reference to means for cutting the thread of a sewing machine
when required and more particularly to means of that character most suitable for
use in a single thread chain-stitch machine.
Thread-cutters frequently employed upon lock-stitch machines are usually
arranged on the presser-foot, presser-bar or other convenient part. of the machine
above the work plate, and in using them the operator draws the work from under
the foot, and severs the threads by bringing them against the edge of the cutter.
In chain stitching it is important (in order to prevent ravelling) that the thread
should not be cut off close to the last stitch, and the proper practice is to draw
down a sufficient length of thread and break or cut it between the work and the
needle so as to leave a half inch or more of single thread through the last loop.
Users of these machines do not always exercise this care, and the common
practice particularly with operatives in factories, is to break the thread off in the
act of pulling out the piece of goods; in other words to pull the goods until the
thread breaks wherever it will. Experience shews that, in this case, the thread
almost invariably breaks just at the last loop, or so near it that the end readily
slips through, and ravelling begins.
The object of the present invention is to provide means by which the thread
is or may be cut when the work is pulled out of the machine, but at a point leaving
sufficient length of thread projecting through and beyond the last loop for the
latter to hold by. To this end the invention consists in combining with the
rotary hook or looper, a thread cutter moving therewith, and placed in such
relation to the loop of thread as to sever it at the desired point when called into
action.
To answer satisfactorily the purposes of the invention it is necessary that the
thread-cutter while so constructed that it cannot cut the thread so long as the
looper is rotating in the proper direction, can still be readily and quickly brought
into action when required. Unless its use is made extremely easy, involving little
trouble or delay, the users probably would continue to pull the work out of the
machine, as before explained without regard to the point of breakage of the
thread. In carrying out this invention, therefore, the thread cutter is so arranged
that it is in convenient position to cut the loop when the looper is arrested to
remove the work, that is to say, when the needle is out of the work and at or near
its highest point. At this moment the edge of the cutter which is turned opposite
to the direction of the looper's rotation, has just passed the thread so that the
operator, by reversing slightly the motion of the shaft, engages the thread with
the cutting edge, and a comparatively gentle pull upon the goods severs the thread
at the proper point.
many
different ways,
The principle of the invention may be carried out in
several of which, by way of example will be hereinafter explained.
When the needle is at its highest point there is a loop of thread passing around
the hook near its middle part, and the preceding loop is about being released by the

page_text: cast-off or tail of the hook. It is preferred to cut the loop which at this moment
passes around the body of the hook, and for that purpose the cutter may be placed
in any convenient position on the hook or relatively thereto, provided its cutting
edge is in juxtaposition with the line then occupied by the thread when the needle
is at its highest point.
In what is considered the best embodiment of the invention, the thread-cutter is
placed on the disc or thread-guard which stands between the looper and the end of
the looper-shaft and the cutter is in the form of a curved flange projecting from
the edge of the said disc into the space between the tail of the looper and the
spreader. The edge of this flange is inclined outward in a direction opposite to the
rotation of the shaft, and the cutting edge is formed on the end of the flange. So
long as the looper revolves in the proper direction there is no contact of the thread
with the cutting edge. The inclined or cam edge pushes the thread coming down
from the needle inside of the looper away from the disc or thread guard until the
flange has passed the thread, when the latter springs back. At this moment if
the machine be arrested and slightly reversed the cutting edge comes against the
thread. In all the embodiments of the invention herein described there is a part
or device which acts as a deflector, to guide the thread past the cutting edge, so
that the latter cannot engage the thread during the operation of forming stitches.
The invention will be explained more in detail in connection with the
accompanying drawings which form part of this Specification and in which
Figures 1, 2, 3 and 4 are sectional elevations looking towards the end of the
looper shaft, shewing the looper and thread cutter in various positions.
Figures 5 and 6 are sectional elevations looking towards opposite sides of the
looper shaft.
Figure 7 is a side elevation of a looper provided with a thread cutter whose
construction is slightly modified.
Figure 8 is a front elevation and Figure 9 a side elevation of a looper having a
different form of thread cutter.
Figures 10 and 11 are respectively a sectional elevation and a corresponding
underside view of a looper having the cutter situated under the nose or point of
the looper.
Figures 12 and 13 are views at right angles to each other of a looper having
the cutter situated on the inside, that is the side adjacent to the looper shaft.
The looper B illustrated in the drawings is that used in the Willcox & Gibbs
single thread chain stitch machine, the construction and operation of which are
well known. The presser-foot is omitted from the drawings.
According to the construction illustrated in Figures 1 to 7 the thread-cutter a is
in the form of a thin piece of steel at a right angle to the disc or thread guard b
which protects the thread from oil that may flow from the bearing on to the looper
shaft, and which stands between the looper B and its pin or spindle m by which it
is attached to the looper-shaft. The cutter projects forward from this disc into the
space between the cast-off or tail c of the looper, and the loop spreader d, and its
outline is clearly shewn in Figures 5 and 6. It has an inclined thread deflecting
edge e and a cutting edge f, the latter being preferably as shewn, inclined forward
from its inter-section with the deflecting edge, that is to say, inclined in the
direction of the rotation of the book (indicated by the arrows, Figures 1 and 2)
so that such rotation, after the thread has reached this point, carries the cutting edge
away from the thread, and a slight reversal is required to bring them into
contact.
This feature is preferably adopted whatever form the thread-cutter may take.
The function of the deflecting edge e is to deflect the thread which comes down
from the fabric D between the guard b and the hook B. This action is clearly
shewn in Figure 5 in which the dotted line indicates the position the thread would
occupy if the thread cutter were removed, and it also indicates the position the back
tbread occupies after it has passed the corner or point of the thread-cutter.
Figures 1 to 4 show successive positions of the parts illustrating the manner of

page_text: using the thread-cutter. In Figure 1 the needle A is ascending and near its highest
point, and the thread is gliding along the deflecting edge e of the thread cutter.
In Figure 2 the rotation of the looper, in the direction of the arrow, has carried the
cutter past the thread which has sprung back behind it. To sever the thread the
operator having brought the parts to this position, turus the main shaft backward
that is in the direction indicated by the arrow in Figure 3 thereby engaging the back
portion of the loop with the cutting edge a as shewn in Figure 3. If now the
presser foot be raised and the work be pulled out, the thread will be severed at the
cutting edge, as shewn in Figure 4 leaving the length of thread g projecting
through the loop last formed. Or instead of pulling on the work to sever the thread
the same result is obtained by turning the shaft a little further back than shewn
in Figure 3 so as to bring sufficient stress of the cutting edge f on the thread to
sever it at that point.
In Figure 7 the cutter is shewn as having two cutting edges f and f¹ to increase
the certainty of action. If when the machine is arrested the shaft has not advanced
far enough to bring the edge f past the thread it will be engaged by the
supplementary edge f¹.
As shewn in Figures 8 and 9 the cutter a is placed at the rear of the cast off c the
said cutter being made of a thin flat piece of steel let into a groove in the rear
edge of the said cast off or it may be made solid with the looper.
The cutting edge f in this modification is as in those previously described,
inclined forward from the point of the cutter. It does not act upon the loop i
(Figure 8) passing around the body of the looper, but upon the preceding loop h
which is just leaving the looper.
In the
As shewn in Figures 10 and 11 (the latter being an underside view of the hook
in the same position as in Figure 10) the cutter a is let into the body just under
the point of the looper. Its outline is shewn by dotted lines Figure 10. The edge e
acts as the deflecting edge and f represents the cutting edge as before.
position shewn in the drawings the looper has been turned until the thread has
passed the point of the cutter, and then reversed until the thread is brought against
the cutting edge, at which position of the looper the point of the needle is about
at the level of the underside of the presser-foot when the latter is raised.
The cutter shewn in Figures 12 and 13 is of the same general form as that last
described, and is secured to the side of the looper adjacent to the end of the shaft.
Its action will be fully understood from the drawings in connection with the
explanations already given.
Other modifications may be made in the form and location of the cutter, without
departing from the nature of the invention.
Although the looper is a part of an organised sewing machine, and has no function
except in connection with other stitch-forming devices it is a detachable part and
may be manufactured and sold as a distinct article. I therefore claim a sewing
machine looper when provided with a thread cutter separately, as well as in
combination with other parts of a sewing machine.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is.-
1. A thread cutter arranged to be carried by the rotatory looper of a sewing
machine and to be used for severing the sewing thread substantially as herein-
before described and as illustrated in the accompanying drawings.
2. In a chain-stitch sewing machine, the combination with the needle and rotary-
hook or looper, of a thread cutter having its cutting edge carried by the said book
or looper inclined from its point in the direction of the rotation of the said hook or
looper, so as to engage the thread upon reversal of the movement of the said hook
or looper substantially as herein before described.
3. The combination with the rotary looper B of a thread cutter having a thread

page_text: deflecting edge and a cutting edge intersecting the latter and inclined therefrom in
the direction of the forward rotation of the looper substantially as described.
4. The combination with the rotary looper of a thread cutter rotating therewith,
and having its cutting edge arranged in the space between the tail of the looper
and the spreader, substantially as described.
5. A combined looper and thread cutter constructed substantially as hereinbefore
described with reference to the several modifications illustrated by Figures 1 to 6
Figure 7, Figures 8 and 9, Figures 10 and 11 and Figures 12 and 13 of the
accompanying drawings.
Dated this 28th day of August 1894.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, Agents.