Stitch-forming Mechanism for Buttonhole Sewing Machines.
Year: 1899

page_text: Date of Application, 10th Aug., 1899-Accepted, 23rd Sept., 1899
COME DRIED MORTUATION.
[Communicated from abroad by THE SINGER MANUFACTURING COMPANY, of New
York, United States of America, Sewing Machine Manufacturers.]
Stitch-forming Mechanism for Buttonhole Sewing Machines.
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 relates to improved stitch-forming mechanism for button-hole
sewing machines. The object of the invention is to provide improved mechanism
for what is known in button-hole stitching as the "pearl stitch," a close imitation
of the best character of hand-worked button-hole stitching. My improvements
are designed to be attached to any of the well-known button-hole sewing machines
in place of the other stitch-forming mechanism used thereon.
Machines of this class have heretofore employed two loopers, one of the loopers
having an eye carrying a lower thread; and two spreaders.
In these prior
machines two threads have been employed, the upper one being carried by the
machine needle, and the lower one by the looper having the eye. The features
of my invention consist in providing the spreaders with a certain cam-end; in
providing each of the two loopers with an eye; and in employing two lower
threads instead of only one, the improved machine thus employing three threads.
The invention is illustrated in the accompanying drawing in which,
Figure 1 is an inverted or bottom view of the bed of a button-hole sewing
machine, showing my invention.
Figure 2 is a view of the spreaders separately.
Figures 3, 4, 5 and 6 show the improved spreaders, and the two loopers each
with an eye; the parts as shown being in the inverted position. Said figures
show the several successive positions the parts take in forming the right hand
half of a "pearl stitch," Figure 3 showing the position of the parts at the
beginning of the stitch.
Figure 7 is a view of the stitch-forming parts in position for making the left
hand half of "pearl stitch."
Figure 8 is a vertical section of plate having the needle-slot, and shows the
needle and loop of upper thread.
It should be stated that my invention has nothing to do with mechanism for
operating the needle, nor with the feed mechanism, nor yet with mechanism for
operating the looper-carrier, it being understood that my present improvements
may be employed in connection with any of the well-known mechanisms for the
several purposes, that are suitable.
Referring to the drawing the letter L designates the ordinary cord spool used
in button-hole machines, and n, n¹, designates the two lower threads, each being
on a separate spool. The spool for the upper thread which passes to the needle,
is not shown. The employment of two separate lower threads with the upper
thread, is therefore a feature of my improvement.
The looper-carrier A, oscillates immediately below the two spreaders C, C¹..
The looper-carrier is pivoted at a, on a bracket arm B, and projecting from said
carrier is an arm b, to which is attached the rod b', that imparts movement. The
looper-carrier A, at a point opposite the arm b, has a roller c, which acts on the
cam surfaces of the spreaders C, C¹. The two loopers d, d', are of the same length

page_text: instead of being as usual, of unequal length, and each has a longitudinal groove
and at its point has an eye; thus each looper carries one of the two lower
threads n, n¹.
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The two spreaders C, C¹, are each pivoted by a screw e, to a plate f: two
stop-pins g, are on the plate f one for each spreader to abut against, and a
spring h, acts on each spreader and serves to press it against the stop-pin.
The form of the spreaders is shown on the drawing; each spreader has at its
thread-operating end a notch which forms a hook by which one of the lower
threads is engaged. The function of the hook i, on the left hand spreader C,
is to engage the lower thread n', of the right hand looper d¹. The function of
the hook 2, on the right hand spreader C, is to engage the lower thread n of
the left hand looper d. Each spreader has a cam-arm j, on which the roller c,
of the looper carrier acts. This general form of spreader is not my invention,
but I have added to the cam-arm a new feature consisting of a convex inward-
curved cam-end marked k, on one, and k¹ on the other arm. Each of the cam-
arms j has, at a point near its pivot e, an inward shoulder m, and between the
said cam-ends and the shoulders, on each of said cam-arms, is a hollow or
concave portion l.
An ordinary take-up spring-device q, is employed with the lower spool
thread n, and a similar device q' is employed with the other lower thread n².
These take-up devices draw back the slack and ensure the proper tension on the
threads.
The operation of forming the stitch is as follows:-
The needler comes down through the fabric adjoining the slit of the button-
hole, and then, by a slight upward motion of the needle, the upper thread is
thrown out laterally into the form of a loop p, see Figure S, through which one
of the lower threads, say n¹, is carried by the right hand looper d' moving from
right to left. (See Figure 4.) The left spreader C at this juncture is moved
slightly horizontally by the roller c bearing against its convex cam-end k; the
hook on the left spreader is thereby moved aside sufficiently to permit the lower
thread n of the left looper to pass to one side of the said left spreader and thus
prevent said thread from engaging with the hook i on the left spreader; and
this is the function of the new convex cam-end k, or . The next position in
succession is shown in Figure 5 which represents the roller c in the concave
portion of the cam-arm j, thus permitting the said spreader C to be drawn into
contact with the stop-pin g by the spring h, and in which position of the spreader
the lower thread n of the left looper d is still to one side of the said spreader C,
and the parts are now in position for the hook i on the left spreader to engage
the lower thread n' of the right looper d¹. As the looper carrier A continues to
swing towards the left, to complete its oscillation, the roller c will contact with
the inward shoulder m on the cam-arm and thereby the left spreader is moved
to the full extent of its throw to the position shown in Figure 6, and is retained
in this position until the needle has passed down through the loop formed by the
lower thread n³, of the right looper d', held in the hook i of the left spreader C.
As the needle descends and throws out a lateral loop of the upper thread, the
left looper d swings toward the right, see Fig. 7, the thread loop of the upper
thread which encircles the right looper d' slips off, and is drawn upward toward
the fabric by the descent of the needle through the buttonhole slit in the fabric
and the action of the upper take-up spring, which is of ordinary construction.
As the left looper swings toward the right the lower thread n¹, remains around
the needle in its position at the left hand end of the needle slot, the said lower
thread n', has thus formed a loop about the loop of the upper thread brought
down by the needle through the buttonhole slit. Furthermore as the left looper d
swings fully to the right, it passes through the lateral loop of upper thread and.
its lower thread n is also carried through, and the roller c will strike the inward
shoulder m of right spreader C, and throw it aside to its fullest extent, the
book of the right spreader carrying the lower thread n, between the left looper

page_text: and the fabric so as to form a loop through which the needle may descend in
passing down through the fabric.
As the needle descends and then throws out a lateral loop of the upper thread,
the left looper swings towards the left, the loop of the upper thread which
encircles the left looper slips off the point and is drawn up towards the fabric
by the descent of the needle through the fabric and the action of the take-up
device on the upper thread together with the action of the right looper.
The operation is the same with the right and left spreaders and the right and
left loopers.
Any buttonhole sewing machine may be altered, and the parts herein described
as my construction may be substituted.
It is obvious that the form of looper-carrier here shown may be varied, and
that the construction of the spreaders may also be varied.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:
1. In a buttonhole stitch forming mechanism, the combination of a looper-
carrier having two loopers each carrying a different lower thread; a needle
carrying an upper thread; two separately-pivoted spreaders each of which engages
a different lower thread, and mechanism for operating the said elements, whereby
a stitch is formed by the employment of three threads.
2. In a buttonhole stitch-forming mechanism, the combination of a looper-
carrier having two loopers of equal length and each carrying a different lower
thread; a needle carrying the upper thread; two spreaders each having a hook
which engages the lower thread of a different one of the loopers; and mechanism
for operating the said elements.
"
3. In a button-hole stitch-forming mechanism, the combination of a looper-
carrier having two loopers termed "left-hand looper" and a "right-hand looper
each carrying a different lower thread; two spreaders, to wit, a left and right,
each having a hook, the hook of the left spreader arranged to engage the lower
thread of the right-hand looper, and the hook of the right spreader arranged to
engage the lower thread of the left-hand looper; a needle carrying an upper
thread, and mechanism for operating the said elements.
4. In a button-hole stitch-forming mechanism, the combination of a looper-
carrier having two loopers of equal length and each carrying a different lower
thread; two separately-pivoted spreaders each having a cam-arm provided with
an inward-curved cam-end kork, an inward-projecting shoulder m, near the pivot,
and a hollow concave curve 1, between said cam-end and shoulder: a roller on
the looper-carrier said roller acting on the parts of the cam-arm of the spreaders;
a needle carrying an upper thread, and mechanism for operating the said elements.
5. In a button-hole stitch-forming mechanism the combination of a looper-
carrier having two loopers each carrying a different lower thread; a needle
carrying the upper thread; and separately-pivoted spreaders each having a cam-
arm provided with an inward-curved cam-end and an inward-projecting shoulder
near its pivot and mechanism for operating the said elements, whereby a pearl-
stitch is formed by the two lower threads interlocked by the uppepr thread passing
through the loops of said two lower threads.
T
1000
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents,
62, Saint Vincent Street, Glasgow,
Agent for the Applicant.