Thread Cutting Device for Sewing Machines.
Year: 1899

page_text: Date of Application, 14th July, 1899-Accepted, 26th Aug., 1899
[Communicated from abroad by THE SINGER MANUFACTURING COMPANY, of New
York, in the United States of America, Sewing Machine Manufacturers.]
Thread Cutting Device for Sewing Machines.
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I, JOHN KING MACDONALD, Manager of The Singer Manufacturing Company,
Kilbowie, Dumbartonshire, 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 has for its object to provide a thread-cutting mechanism
applicable to machines for sewing on buttons, stitching button-holes, barring
button-holes, forming bars or stays, and the like, and by means of which the
thread or threads running between button-holes or groups of stitches may be
severed in two places so as to cut out pieces of thread and thus remove the
surplus thread from the work. To this end I provide two shear thread cutters
or thread cutting devices which are separated from each other a distance equal to
the length or piece of thread to be cut out, said thread cutters being prefer-
ably automatically operated at the proper intervals, or after each button-hole,
bar, or stay, or other group of stitches has been formed, thus severing the
thread or threads close up to the bar or other group of stitches just formed and
also close up to the bar or other group of stitches about to be formed, so as to
cut off the thread or threads close to both sides of each bar or group of stitches.
In the accompanying drawings Fig. 1 is a rear side elevation of a button
sewing machine embodying the invention. Fig. 2 is a partial front end view of
the same on a larger scale than Fig. 1. Fig. 3 is a partial rear side view on the
same scale as Fig. 2 to show the cutting device, and Fig. 4 is a front side view
of the cutting device. Fig. 5 is a detail sectional view on the line 5-5, Fig. 2.
The machine to which I have shown my present invention as being applied is,
in its general construction and operation, substantially the same as the button
sewing machine fully shown and described in the Specification of Letters Patent
No. 30,183, dated 21st December 1897, and comprises mechanism for making a
group of a predetermined number of overseaming stitches in one place for the
purpose of attaching the shank or eye of a button to a shoe or other article,
and after the desired number of stitches has been formed the machine is auto-
matically stopped. The automatic work-feed described in the before mentioned
specification is omitted from the present machine, and in the operation of the
present machine the attendant shifts the work from one button-sewing position
to the next, the presser-foot being raised by the treadle-operated lever O when
the work is to be shifted. As the machine forms lock stitches comprising an
upper or needle thread carried by a needle d and a shuttle or lower thread
carried by a shuttle e, these threads would, if not severed, extend loosely from
group to group of button-attaching stitches on both sides of the work. The
loose shuttle thread, being on the back or wrong side of the work, and thus
ordinarily concealed, is not seriously objectionable but the loose thread on the

page_text: face or right side of the work presents an unsightly appearance, and has hereto-
fore been trimmed off by hand with scissors. This hand trimming of the needle
thread is done away with by the present invention which provides means for
automatically cutting out the surplus loose needle thread between the groups of
button-attaching stitches.
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In the form of my invention herein illustrated two thread cutting knives or
blades a a are attached to a cutter-lever a pivotally attached by a pin b to the
stock portion 66 of the presser-foot comprising two parts b¹ and be between which.
and beneath the stock 66 is formed a thread receiving slit or thread guide b³.
Any suitable stationary parts, as 64, 65, on the presser-foot and its shank, to
cooperate, as ledger blades or otherwise, with the blades a a may
provided. The movable blades a a, and the ledger blades, consisting
of the parts 6, 5, of the presser-foot, constitute shear cutters, as will
Be readily understood from the drawings, and more particularly from
Fig. 5. The cutter lever a¹ is connected by a link or bar e with the lower end
of the lever m³ which operates the button-feeder m through the rock-shaft M
and the rod m², said lever m³ being actuated from the cam groove e³ of the inter-
mittingly rotating cam cylinder E, as in the machine shown in the Specification
of Letters Patent before referred to. As the movement of the lower end of the
extended lever m³ is somewhat greater than is necessary to produce the required
movement of the cutter-lever a¹ the bar or link c is provided with a slot c¹ in
which the pin or screw 2, connecting said lever and bar or link, can have a
limited play, so that the button-feeder m will have performed part of its move-
ment before the cutter-lever is operated to cut out the thread by the two separated
blades or cutters a, a, which are spaced or separated from each other a distance
equal to the length of the piece of thread to be cut out.
To vary the length of the piece of thread to be cut out by the separated thread
cutters, interchangeable cutting devices with differently spaced cutters may be
employed. This same result might be secured by mounting the cutters in such
a way that they may be adjusted from or towards each other by a screw or other
adjustment.
From the foregoing it will be understood that after a group of button-attach-
ing stitches have been formed and the work has been shifted to bring it into
position to sew on another button, the thread-cutters will be automatically
operated to cut out the surplus needle-thread which would otherwise extend
between the two groups of button-attaching stitches. The thread-cutters are
actuated, to cut out the surplus thread, when the needle d, is in the raised
position which it assumes when the machine is stopped by the automatic stop-
motion mechanism shown and described in the Specification of Letters Patent
before referred to, and owing to this raised position of the needle the needle
thread is drawn into the slit 3 of the presser-foot, and as the attendant will
hold the work slightly lifted rearward of the presser-foot the needle-thread will
be brought within the range of the blades or cutters a, a.
While I have illustrated my double thread-cutter, adapted to cut out a piece
of thread, in connection with a button-sewing machine, it will be understood that
it is equally applicable to button-hole stitching, or to barring or staying
machines, or to other machines forming groups of stitches with loose threads
between them, and I do not therefore wish to be understood as limiting my
invention to any particular form of sewing machine. Also, instead of operating
this double thread-cutter automatically it might be actuated manually by the
attendant, or it might be arranged to sever the shuttle or looper-thread, without
departing from the spirit of my invention.
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. In a sewing machine, the combination with a presser-foot provided with

page_text: a thread-receiving slit, as 63, of two separated or spaced shear thread-cutters
mounted on said foot and each adapted to make a separate cut through a thread
extending in said slit from one cutter to the other, so as to cut out a piece of
thread, and means for actuating said thread cutters.
2. In a sewing machine, the combination with a presser-foot provided with
a thread-receiving slit, as 63, of two separated or spaced shear thread cutters,
a cutter-lever pivotally attached to said foot and by which said blades or thread
cutters are carried, and means for operating said lever.
3. The combination with a sewing machine presser-foot having the cutting
parts 64, 65, and a thread-slit 3, of the cutter lever a pivotally attached to said
foot, the separated blades or cutters a, a, carried by said lever, the bar or link c,
the lever m³ and a cam for operating said lever m³.
4. In a sewing machine, the combination with the stitch-forming mechanism
thereof, of two separated or spaced thread-cutting devices adapted to cut out a
length or piece of thread, said thread cutting devices each comprising a cutting
blade and an opposing cutting device, guiding means for directing the thread
to said cutting devices and means for operating said blades.
5. In a sewing machine, the combination with the stitch-forming mechanism
thereof, of two separated or spaced thread cutting devices adaped to cut out a
length or piece of thread, said thread cutting devices each comprising a cutting
blade and an opposing cutting device, guiding means for directing the thread
to said cutting devices and automatic means for operating said blades.
Dated this 13th day of July.
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents,
62, Saint Vincent Street, Glasgow,
Agent for the Applicant.
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents,
62, Saint Vincent Street, Glasgow,
Agent for the Applicant.