Improvements in Double-thread Sewing Machines.
Year: 1890

page_text: Date of Application, 20th Feb., 1890-Accepted, 22nd Mar., 1890
COMPLETE SPECIFICATION.
Improvements in Double-thread Sewing Machines.
I, FRANK HUGHES, of the firm of Hughes Eli and Hughes, of 76 Chancery Lane,
London, W.C., Patent Agents and Engineers, do hereby declare the nature of this
invention (a communication to me from abroad by Ebenezer Baker Welch of 186
Main Street, Cambridge, State of Massachusetts, United States of America, Gentleman)
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The object of this invention is to furnish an improved double thread sewing machine
of a simple and durable character. My improvements relate first to a horizontally
oscillating curved hook provided with a peripheral groove and eyes to hold and
carry the under thread through a loop of the upper thread on the needle and with a
central cam which is formed to spread and hold a loop or bight of the lower thread in
position to receive the descending needle and to release or throw off said loop after
the needle has entered it.
My improvement also relates to certain combinations of devices and minor improve-
ments all of which I will now proceed to describe and claim.
Of the accompanying drawings forming a part of this specification, Figure 1
represents a front elevation of a sewing machine provided with my improvements.
Fig. 2 represents an end elevation of the same, the work plate being shown in section.
Fig. 3 represents a section on line xx Fig. 2. Fig. 4 represents a section on line y y
Fig. 3 looking downwardly. Fig. 5 represents a section on line z z Figs. 1 and 3 and
side elevation of the thread hook. Figs. 6 and 7 represent side elevations of the
thread hook in different positions. Fig. 8 represents a top view of the thread hook.
Figs. 9-13, inclusive, represent perspective views of the thread hook and needle
showing different stages in the formation of the stitch. Fig. 14 represents a bottom
view of a part of the work plate showing the thread hook in dotted lines. Fig. 15
represents a section on line Fig. 14. Fig. 16 represents a section on line y¹ y¹
Fig. 14.
Similar letters of reference in the several Figures indicate the same parts.
In the drawings-
A represents the table to which the base B of the machine is secured. From
this base the goose-neck or
arm Crises in the usual manner. D represents the
needle lever pivoted at E and actuated by an eccentric on the main shaft F and by
a pitman G connected at its upper end with the short arm of said lever. H repre-
sents the thread hook which is attached to a substantially vertical stem or arbor H'
and is composed of a curved portion 2 (Fig. 8) about concentric with the axial center
of said arbor and a radial arm 3 connecting the portion 2 with said arbor, the upper-
side of the hook being substantially horizontal so that it moves in a plane about at
right angles with the line of movement of the needle N. The periphery of the hook
has a groove 6, for the reception of the under thread and two or more (preferably
three) eyes 7, forming continuations of said groove to retain the thread in the groove
one of said eyes being at the heel, another near the point and the third at about the
middle of the periphery of the book. The orifice of the thread eye at the point of
the hook is on the same curve as the remaining portion of the groove 6 for a purpose
hereinafter described.
The stem or arbor H³ of the hook is journalled in a bearing block R attached
to the frame or base of the machine and is grooved to form gear teeth 8 meshing
with similar teeth 9 on a horizontal rod J which is reciprocated longitudinally (but
is not capable of rotating) in the block R and by its reciprocating movements
oscillates the arbor H2 of the hook thereon.
The rod J is reciprocated in this instance, by means of an arm or extension D' on
the needle leser and a connecting rod L pivoted to said arm and to an ear K affixed

page_text: to the rod J by means of a screw K¹. By loosening the set screw K' the rod J may
be turned to present a new portion of its toothed surface to the shank of the thread
hook, hence as the rod becomes worn it may be adjusted to bring unworn portions
into operative positions.
At the center of the hook or upon the end of the stem or arbor, is the cam or
hub H which has a concave side 4 and a convex side 5, said concave side during a
portion of the oscillating movement of the hook co-operating with the point of the
hook in spreading and holding open a loop of the under thread so that the descending
needle may pass through said loop, while the convex side is so formed that during
another part of the oscillating movement of the hook it will come in contact with said
loop and release or throw it off so that it may be taken up by the subsequent move-
ment of the hook.
Prior to the descent of the needle the hook stands in the position shown in
Fig. 9, the under thread extending from the seam on the work to the point of the
hook in close proximity to the concave side of the hub or cam.
While the needle
is descending the hook rotates backward as indicated by the curved arrow in
Fig. 10, and thus causes the portion of the under thread between the seam and
the point of the hook to bear against the concave side of the hub or cam and
binds said portion partly around the cam in the form of a loop 1, Figs. 10 and 11,
which is prevented from slipping upwardly off from the cam by the concave side 4.
The needle descends while the loop is thus held and passes through said loop.
After the needle has entered the loop and while it is completing its downward
movement the hook continues its backward rotation until the convex side of its hub is
brought against the loop l. The form of the convex side is such that it cannot retain
said loop but releases or casts it off, the loop then embracing the needle and the upper
thread thereon, and being tightened by the completion of the backward movement of
the hook. After the loop is released and tightened the hook rotates forward its point
advancing toward the depressed needle. Just before the point of the hook reaches
the needle the latter begins to rise and in so doing throws out from one of its sides
a loop of the upper thread, said loop being entered by the point of the advancing
hook as shown in Fig. 12, and thus retained on the hook while the needle is rising
and the hook is completing its forward movement as shown in Fig. 13. The needle
in rising leaves the released loop of the lower thread around the loop 11 of the
upper thread which is held upon the hook. The hook then rotates backwardly out of
the upper thread loop, leaving the latter locked by a loop of the lower thread, which
is drawn through said loop by the point of the retreating hook. The operation is
thus continued, each descent of the needle being through a loop of the lower thread
first held and then released by the hub of cam H¹ and each upward movement of the
needle being followed by the entrance of the thread hook into the loop of the upper
thread, then thrown out from the sido of the needle, said hook retaining the upper
thread loop while the needle rises and then moving backwardly to draw the
lower thread through and thus permanently lock said loop, the result being that the
lower thread is first carried around each loop of the upper thread and then drawn
through it. As soon as the point of the hook withdraws from the upper thread loop l¹
said loop is drawn or tightened by a take-up consisting of two eyes P¹, R' affixed to
the frame of the machine at opposite sides of the needle bar and another eye on the
needle bar, the eye Q being placed at a point which in the course of the stroke of
the needle bar moves equally above and below the fixed eyes P' R' so that the slack
of the upper thread is taken up both by the upward and downward stroke of the
noedle bar.
I have in some cases found it advantageous to form a downward incline on the.
under side of the thread hook from the point to or partly to the heel as best shown in
Figures 5, 6 and 7. This incline causes the hook in passing through the loop "
of the upper thread, to pull said thread downwardly and thus tighten or set the
preceding stitch.
I have also in some cases employed a spring plate a attached at one end to the
heel of the hook and extending along the under side thereof nearly to the point, its

page_text: opposite end being free. Said plate stands parallel with and so near to the under
side of the hook that it bears upon the loop of the upper thread and prevents said
loop from moving independently or being displaced during the backward movement
of the hook. Said loop is loosened by the backward movement of the hook owing
to the incline above described which draws down or elongates the loop during the
forward movement of the hook, and therefore loosens it during the backward move-
ment. If the loosened loop were free to move laterally on the hook it would be
liable to get in the path of the descending needle and receive the latter. The
spring plate prevents this by retarding the loop or preventing its free movement
toward the needle until the point of the needle has descended below the lower end of
the loop.
The thread eye 7 at the point of the hook preferably extends along the periphery
of the hook in line with the groove 6.
The eye thus disposed causes the under thread to stand off from the side of the
needle, as shown in Fig. 11* when the loop is thrown out from the needle and the
hook is moving forward to enter said loop. The under thread is thus prevented
from pressing against the loop l' so that the latter is free to stand out from the needle
and receive the hook.
e represents a projection on the under side of the throat plate d of the machine,
said projection extending nearly down to the plane of the upper side of the thread
hook and containing the hole e through which the needle passes. Said hole is formed
with a straight and flat side or wall 10, which affords a support for the loop "
of the upper thread thrown off from the needle by the upward movement of the latter
as above described and prevents said loop from yielding when the point of the
advancing book reaches it, thus ensuring the prompt entrance of the hook into said
loop. The needle hole is also provided with a recess 12, at one side of the wall, said
recess receiving the thread of the upper loop when said loop is being taken up.
grepresents a socketed cylindrical holder (Fig. 5) journalled in the block R so as
to be capable of rotating therein, and provided with a socket eccentric to its
periphery in which socket the arbor H' of the thread hook is journalled. It will be
seen that by reason of the eccentricity of said arbor to the periphery of the holder a
rotary movement of the holder in the block R will move the arbor laterally with
relation to the spirally geared rod J so that any lost motion between the spiral gears
of the arbor and rod resulting from wear or other cause can be taken up by a rotary
movement of the holder. A set screw i secures the holder in any position to which
it may be placed.
These movements add materially to the effectiveness and smoothness of the
operation of the machine. I do not limit myself to the conjoint use of all the
specified improvements in one machine. The hook may have its under side parallel
with its upper side instead of inclined, if desired, and the loop-retarding spring may
be omitted. The thread hook may be oscillated by any other suitable mechanism.
I claim―
1. In a double thread sewing machine, an oscillating thread hook having a
curved and peripherally grooved arm, and a projection within the curve of said
arm concave on one side for retaining the thread and spreading the same for the
entrance of the needle and convex on the opposite side for casting the thread off to
engage with the upper thread whereby during a movement of the hook the thread
is first held and then released by said projection and means for oscillating said hook,
substantially as described.
2. The oscillating hook provided with the curved portion grooved on its outer face
and perforated at its heel and point for the permanent engagement of the thread and
the cam or projection at the centre extending above the head of the hook for
spreading and releasing the lower thread combined with means for oscillating said
hook, as set forth.
3. In a sewing machine, the vertical reciprocating needle N carrying the upper
thread in combination with the oscillating book having the projection H' thereon with

page_text: the concave and convex side and the peripheral groove with the retaining loops or
eyes and the eye at the end of the hook whereby the hook is adapted permanently to
carry the lower thread, spread the same for the reception of the upper threaded needle,
and then release said loop to enable the same to be contracted around the upper thread,
substantially as described.
4. The combination of the thread hook having its shank or shaft grooved to form
teeth, the rod J grooved. to form teeth intermeshing with those of the thread hook.
fixed bearings in which said rol is a lapted to be reciprocated to oscillate the thread
hook, a reciprociting device as K, whereby the rol is impelled and means substantially
as described for detachably socuring the rol J to the device K-whereby said rod may
be partly rotated to present different parts of its teeth to the thread hook shank, as
set forth.
5. The combination of the oscillating thread book having its shank or shaft grooved
to form teeth, the reciprocating rod J grooved to form teeth intermeshing with those
of the thread hook moved by the arm K the link L.uniting said arm and the lever D¹
all arranged and operated substantially as described.
6. The combination with the oscillating thread hook having its shank or shaft
spirally grooved forming spiral teeth of the reciprocating rod J, spirally grooved
forming teeth intermeshing with those on the thread book whereby the bearing point
between the two may be changed. and bearings for preventing the rotation of said
rod J, as set forth.
7. In a double thread sewing machine, a vertical shaft, a horizontally arranged
thread looper thereon, a curved hook portion therefor extending in a horizontal plane
and, having an incline. and a loop retarding spring on the under side of the curved
hook as described in combination with means for oscillating said.looper, substantially
as set forth.
8. In a double thread sewing machine an oscillating thread hook having a
peripheral groove and an eye the longitudinal axis of which is in line with said
groove at or near its point to guide the lower thread and cause the same to stand
away from the needle, combined with means for oscillating said hook, as set forth.
9 in a double thread sewing machine, a vertical shaft a horizontally arranged
thread looper mounted thereon, a curved hook portion therefor externally grooved as
described and having a thread oye at its point, the longitudinal axis of said eye being
in line with said groove so as to present a continuation of the latter in combination
with means for oscillating said looper, as set forth.
10. In a double thread sewing machine, the combination of the needle, the thread
hook oscillating in a plane substantially at right angles with the line of movement of
the needle, and perforated at its point and heel to permanently retain the thread, and
the throat plate having a downward projection containing the needle hole, said hole
having a wall which terminates near the upper side of the hook and supports the upper
thread loop while the hook is entering it, as set forth.
11. The combination with a needle and means for reciprocating it, of the toothed
thread hook arbor H', the holder in which said arbor is journalled, said holder being
eccentric to the arbor, the fixed supporting block in which the holder is capable of
rotating and the tooth rod J journalled in said block and engaged with the artor H*
and devices for reciprocating said rod J, as set forth.
"
Dated this 20th day of February 1890
HUGHES, ELI & HUGHES,
76, Chancery Lane, London, W.C., Agents for the Applicant.