Improvements in Double Chain Stitch Sewing Machines.
Year: 1897

page_text: Date of Application, 18th May, 1897-Accepted, 17th July, 1897
[Communicated from abroad by THE SINGER MANUFACTURING COMPANY of New
York, in the United States of America, Sewing Machine Manufacturers.]
Improvements in Double Chain Stitch Sewing Machines.
I, WILLIAM HARVEY INSLEE, 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 as communicated to me, to be particularly
described and ascertained in and by the following statement:—
My Invention relates to that class of sewing machines which form the double
chain stitch by means of an eye-pointed needle and a co-operating thread-carrying
looper; and my Invention has for its object to provide a machine, of the class
referred to, which will be simple in construction and in which the movements are
strong and positive so that the machine will be adapted for very high speeds; the
leading feature of the Invention consisting in the looper-operating mechanism.
In the accompanying drawings Fig. 1 is a sectional side view of a "left-hand "
cylinder machine embodying my Invention. Figs. 2, 3 and 4 are detail views of
the take-up and controlling device for the needle thread. Fig. 5 is a front end
view of the machine, with the face plate of the head and the cap at the front end of
the work-supporting arm or cylinder removed. Fig. 6 is a vertical section through
the standard of the frame of the machine. Figs 7, 8 and 9 are details to show the
looper-carrier and its operating devices. Fig. 10 is an enlarged sectional detail on line
10 10, Fig. 6, to show part of the looper thread controlling device, and Fig. 11
a detail view of the plate forming part of said thread controlling device.
The framework of the machine herein shown comprises the standard A, the
overhanging arm A' and the cylindrical work-supporting arm A². B is the driving
shaft journaled in the lower part of the framework and extending longitudinally
of the arm A, said shaft having a crank connected by a pitman b₁ to an arm o
at the rear end of a rock-shaft C journalled in the arm A, said shaft having at its
forward end an arm connected to the needle-bar to reciprocate the latter
vertically. Secured to and forming practically an extension or continuation
of the shaft B is a supplemental shaft B the extreme outer end of which is bent to
form the inclined crank 2, said shaft B being provided, just rearward of said
crank with an eccentric 63. E is the looper-carrier and e is the eye-pointed, thread-
carrying looper suitably secured to said carrier, the shank of said looper, in the
construction herein shown, fitting in a socket in said looper carrier and being
removably secured therein by a set screw el. The said looper-carrier is provided
with forwardly-extending wings or flanges e which embrace the inclined crank 6ª,
and said carrier is also provided on its opposite sides with laterally extending
pivots or trunnions forming journals having bearings in blocks or bearing
pieces a secured by screws a¹ to the forward end of the arm A². The looper-carrier
is constructed with an opening e' rearward of the wings or flanges 2, the side walls
of said opening constituting a yoke in which the eccentric 63 works. Thus when
the machine is in operation the crank 2, working between the wings or flanges e³,

page_text: will impart a rocking movement to the looper-carrier E on its pivot or trunnions e³,
while the eccentric working in the opening or yoke e', imparts lateral movements
to the looper-carrier, the pivots or trunnions e³ of the latter sliding laterally in
their bearings in the blocks a. The crank 6 and eccentric 63 are so arranged and
timed relatively to each other that the looper e will, in its vibrating or rocking
movements, pass forward on one side of the needle, to take a loop of needle thread,
will then be moved bodily laterally so as to rock backward on the other side of
the needle as the latter descends for the next stitch, and passes its thread into a
loop of the looper thread, as is necessary in making the double chain stitch scam.
As these rocking and sliding movements of the looper-carrier are all communicated
from the operating shaft B' and are strong and positive it will be obvious that this
looper mechanism is comparatively noiseless and is well adapted for a high speed
machine.
I is
On the shaft B₁ is an eccentric & forming part of the feeding mechanism, but
as this mechanism is not herein claimed it need not be further described.
a removable cap which, in the form of machine herein shown, serves as a housing
for the looper and feed mechanism.
To properly handle the needle thread I have provided a take-up and controlling
device which I will now describe. The needle-bar 1) carries two separated plates d
provided with thread eyes and between said plates is secured a thin plate or fin d'
to serve as a thread lifter or take-up. F is a small bracket attached to the frame
or head of the machine and having at its lower end a horizontal, inwardly project-
ing finger which is straddled by the thread-eye plates 1, said finger f and the
lower part of the bracket immediately above it being grooved at f1 for the reception
of the outer edge of the take-up fin d¹, said groove terminating at its upper end
at the inclined ledge f2. Attached to the bracket F is a light check-spring f³
the free lower end of which presses against the inside face of the part f' of said
bracket. The operation of this take-up and thread controlling device is as
follows: When the needle has descended to its lowest point the parts are in the
positions shown in Fig. 2 and the needle-thread which runs from the eye of one
of the plates & to the other will be drawn over the finger f which thus draws the
loop of needle thread off from the point of the retreating looper and also prevents
too much slack from being taken down by the needle, and the formation of a loop
on the side of the needle opposite that from which the looper is to take the needle
loop is avoided; this action being assisted by the thread-lifting fin d' which,
as the needle rises, lifts the thread from the finger f and carries it upwards until
the top of said fin reaches the top of the groove f1 at the inclined ledge f
when the thread slips off from said fin but is subsequently lifted by the eyes in the
plates d far enough to properly set the stitch. When the needle next descends
the cheek spring f' momentarily detains the thread and thus holds the slack up
out of the way of the point of the descending needle. The thread is drawn
beneath said check-spring, on the descent of the needle-bar, by the eyes of the
plates, and is prevented by the finger f from being drawn below the lower end
of said spring.
The looper-thread is controlled by the take-up device consisting of an arm G,
attached to the lower end of the pitman at the crank of the shaft B, a stationary
plate H attached to the lower part of the standard A. and co-operating thread-
eyes also on said standard. The arm G is forked or bifurcated at its outer
end to embrace or pass on both sides of the plate H, and the latter has an arm
or portion having at its upper part a convex edge h¹ which extends slightly
within the concaved grooved edge portion 2 of the plate H, there being space
enough between these convex and concave edges for the passage of the thread,
but the latter will be bent enough so that there will be a slight friction or drag
nereon when passing between these two edges, one of which is partly housed
within the other. Below the parts of the plates II and h, one of which is thus
partly housed within the other, is an open slot h³ and the thread will be free from
drag or friction when therein.

page_text: The operation of this looper thread take-up is as follows: When the looper i;
retreating or making its backward movement the take-up arm G is, in the rotation
of the crank b, projected outwards as denoted by dotted lines in Fig. 6, so as to
engage the thread running between the thread eyes or guides and it the same
and thus take up the slack occasioned by the backward movement of the looper,
said arm G moving inward out of engagement with the thread before the looper
has quite completed its backward movement. Before the arm G has become
disengaged from the thread the latter has been lifted so as to be between the
convex and concave edges h¹ and h², so that there will be a slight frictional drag
thereon when the looper commences its forward movement, this frictional drag,
while not amounting to an appreciable tension sufficient to constitute a thread
stop, being check enough on the thread to prevent slack as the looper moves
forward, and this frictional drag being entirely removed when the thread is draw.
downward into the open slot h³.
Owing to the fact that the looper carrier E is supported on both sides by pivo's e³,
so that power can be directly applied to said looper carrier, centrally thereof,
it will be obvious that the said carrier is so firmly supported that there will be
no perceptible jar or vibration of the same in its movements, no matter at how
high a speed the machine may be run; and this feature of providing supporting
pivots or journals on both sides of said carrier, on which it can rock, therefore con-
tributes largely to the efficiency of my Invention as a high speed and comparatively
noiseless machine.
In the operation of an eyed or thread carrying looper co-operating with the
needle in the formation of a double-chain stitch seam it is necessary that the
movements of the looper in the direction of its length should be comparatively
long, while the transverse movements of the looper, to carry it on opposite sides
of the needle, are relatively short. My new machine is so organized that the
longitudinal movements of the looper are effected by rocking the looper carrier E
on its pivots or trunnions e³, so that there is but little friction in effecting the
relatively longitudinal movements of the latter, while the relatively short trans-
verse movements of the looper carrier are effected simply by sliding said carrier
bodily laterally on its pivots or trunnions, and thus the different necessary move-
ments of the looper carrier are effected in a strong and positive manner, and with
a minimum amount of friction.
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 I
claim is:-
1. In a double chain stitch sewing machine, the combination with a needle and
its operating mechanism, of an eyed or thread-carrying looper, a vibrating and
transversely moving looper-carrier consisting of a bell-crank lever, and mechanism
for imparting to said looper-carrier rocking movements in the direction of the
length of the looper, and sliding movements transverse of the length of the looper,
to vibrate the said looper and to move it laterally bodily.
2. In a double chain-stitch sewing machine, the combination with a needle and
its operating mechanism, of an eyed or thread-carrying looper, a looper-carrier
mounted to slide laterally and provided with wings or flanges and with a yoke,
and a rotating shaft having a crank working between said wings or flanges, to
vibrate said carrier, and an eccentric working in said yoke and thus serving to
slide said carrier laterally.
3. The combination, in a double chain-stitch sewing machine, of a needle and
its operating mechanism, a rotating shaft provided with a crank and an eccentric,
the looper-carrier E provided with the looper e, the flanges or wings e embracing
said crank, the pivots or trunnions e³, and the yoke or opening et embracing said
eccentric, and suitable fixed bearings for said pivots or trunnions.
4. In a double chain stitch sewing machine, the combination with the needle
and looper and their operating mechanism, of a take-up and controlling mechanism

page_text: for the lower thread consisting of the take-up arm G placed within the lower part
of the standard A, and bifurcated at its outer end, operating mechanism for said
take-up arm, the plate H having a portion one edge of which extends slightly
within a groove in said plate, to exert a slight frictional drag on the thread, at
times, and stationary thread eyes on opposite sides of and co-operating with said
take-up arm and said plate.
5. In a double chain-stitch sewing machine, the combination with the needle
and an eyed or thread-carrying looper and their operating mechanism, of a take-
up and thread controlling device for the needle thread consisting of the fixed
bracket F having the horizontally projecting finger f, the groove f' and the inclined
ledge above said finger, the thread lifting fin or plate and the plates d
arranged on opposite sides of said fin or plate and provided with thread eyes
which are below the top of the said fin or plate, the latter and the said plates d
being connected to the needle-bar to be movable vertically therewith, said thread
eye plates being arranged to straddle or pass on opposite sides of said finger f,
and the said thread lifting fin or plate being arranged to have its outer edge
project into the said groove fl, the said finger f being so located relative to the
movements of the thread eye plates that the eyes of the latter pass a considerable
distance below the said finger when the needle bar is in its lowest position, said
plates co-operating with said finger to take up the slack thread and tighten the
stitch during the downward movement of the needle bar, and the said fin or plate
serving to lift the thread on the upward movement of the needle bar until the top
of said fin or plate comes opposite the said incline f2 on the said bracket F.
Dated this 17th day of May 1897
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather, Chartered Patent Agents.
62 Saint Vincent Street, Glasgow, Agent for the Applicant.