Year: 1887

page_text: Date of Application, 6th Sept., 1887
Specification Accepted 18th Nov., 1887
We, LORENZ MUTHER, Machinist, and RUSSELL GREEN WOODWARD, Machinist,
both of the City of Chicago, in the State of Illinois, and United States of America,
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:-
In the drawings, Figures 1, 2, 3 and 4, represent a vertical section through the
cloth plate of a sewing machine and a side elevation of the trimmer in the four
different positions assumed by it at the respective quadrants of the driving shaft's
rotation, certain adjacent parts of the stitch-forming mechanism being also shown to
indicate the relation of the trimmer thereto. Figure 5, is a top or plan view of that
portion of the cloth-plate which is immediately adjacent to the trimmer; Figure 5* is
a plan of the detachable plate Figure 6, is a side view of the trimmer-knife detached;
and Figures 7 and 8, are respectively top and side views of the devices for securing
and adjusting the knife.
It is not deemed necessary to show or describe the general construction of the
sewing machine, since it is well understood, and also because we do not limit our
claim to the use of the improved trimmer upon any particular class of sewing
machines.
Our improvements relate to that class of trimmers wherein a single blade extending
through the cloth plate is caused to reciprocate in a vertical plane parallel to the line
of feed and adjacent to the needle, the purpose of the invention being to obtain the
freest possible action of the knife, to simplify its attachment to the driving mechanism,
and to permit its adjustment towards and from the needle.
In the drawings, A, represents the main driving shaft of the sewing machine,
B' the cloth-plate, B the detachable portion thereof now commonly used in proximity
to the needle, &c., ( the feed-dog, D the head, E the needle bar, F the needle, G the
presser foot, H the presser-foot bar, and I the cloth or material operated upon.
The trimmer-knife L, has its cutting edge slightly inclined, as shown, and extends
down through a narrow slot t, whose relation to the other parts is indicated in
Figure 5, where B is the detachable portion of the cloth plate containing the feed-
slots น, and needle hole i and secured to the main plate B by means of screws j. Pis
a second detachable portion of the cloth-plate, containing the knife slot t, and having
a depressed projection o, (shown in dotted lines) whose upper surface fits beneath the
plate B. The detachable plate P is secured by screws s, and r, the former of which
extends through a slot p, of the plate B into the projection o, and the latter of which
extends through a similar slot q, in the opposite ends of the plate P itself, into an

page_text: under-hanging lug on the main plate B'. The end of a slide R, of the ordinary
construction, abuts against the other edge of the plate P, thus forming the continua-
tion of the cloth plate on that side and said slide moves, in the usual manner, towards
or from the edge of plate P. The slots p and q, permit the lateral adjustinent of the
plate P, (the slide R being moved accordingly) and thus the distance of the knife
slot t, from the needle may be varied, and said slot being entirely within the plate P,
can be made of a width barely sufficient for the knife to enter. A vertical strip m,
about of an inch in height extends, at an angle, from the side of the knife slot for
a short distance back, its purpose being to deflect the cut-off portion or waste away
from the working parts.
Returning now to the other figures, we will describe the attaching and driving
mechanism of the trimmer.
The knife L fits snugly but freely in a slot d, (Figure 7) formed in the front end
of the arm K, where it is hung upon a pin b, having near its head a circumferential
groove c, in which rests the free end of a curved spring g, mounted on the side of
the arm K. By this means we suspend the knife freely, so that it may swing
slightly on the pin b, in a vertical plane, for a purpose to be hereafter explained,
and wo avoid the use of a screw attachment, which is troublesome to handle, when the
knife is to be removed and replaced. The pin b, can be instantly withdrawn or
inserted and the knife detached or re-attached, without the least trouble, and the
spring g, resting in the groove c, prevents any accidental displacement. The arm K
is made in two pieces, as shown more clearly in Figure 7, having lateral projec-
tions, M, N, respectively, the former of which has a groove f, and the latter
fitting therein.
A screw e, extends through a slot in the part M, into the part N,
and thus the lateral adjustment of the front end of the arm K, may be effected, by
the movement of the parts M relatively to the part N.
a
rib n,
This lateral adjustment of the knife carrier is of course to be accompanied by a
similar movement of the plate P, which contains the knife slot t.
The arm K, is pivoted at a, to a downwardly depending piece T, mounted upon
the head D, and power is applied to the arm K, by means of a connecting rod J,
extending up through a sloth, in the cloth-plate and vertically reciprocated by an
eccentric U on the driving shaft A.
The operation of the trimmer is as follows:-
Referring to Figure 1, it will be seen that the arın K, and knife L, are in their
lowest positions, and that the feed-dog C, is entirely beneath the surface of the cloth-
plate, and about to commence its upward movement. The edge of the knife is in
contact with the fabric I, at the end of the last preceding cut.
In Figure 2, the driving shaft A, has rotated a quadrant and the knife L, is there-
fore half way up, the feed-dog also has risen into contact with the fabric, and has
commenced its forward movement.
In Figure 3, the driving shaft has rotated another quadrant, the knife is entirely
up, and the forward movement of the feed is completed. If the knife had been
rigidly attached to the arm K, instead of being freely suspended thereon, it would
during the feed movement, have been compelled, by its angular relation to the arm,
to assume the position shown in the dotted lines, and would have therefore interfered
with the feed by pressure against the uncut part of the fabric, so that the latter
would have been buckled up and dragged. The capacity of the knife to swing on its
pivot b, permits the fed fabric to push it back into the position shown by the solid
lines of Figure 3, without appreciable retardation, and by the time the feed is
complete, the knife is now in its rear-most position and the cut is made, as shown in
Figure 4, which represents the fourth quadrant of the driving shaft's rotation.
The advantages of this mode of operating the knife are as follows
It is well known that a trimmer with an inclined edge will cut more easily than
with a horizontal one, for the obvious reason that a drawing cut is accomplished with
less expenditure of power than a punching, or chiseling cut. For use upon hosiery
and similar fabrics it is desirable that the angle of the cutting edge to the plane of
the fabric should be obtuse, or more than 45°, in order that the cutting may be

page_text: protracted. It is also desirable for mechanical reasons that the trimmer cutter should
be driven from the main shaft of the machine by means of a connecting rod and
pivoted lever arm, such as we employ ; attachment to the needle bar or other driven
part having been found highly wasteful of power and inefficient.
While, however, the use of the pivoted lever as the knife carrier has been common,
the knife has always been rigidly attached thereto, or has been provided with guides
above and below the cloth plate.
Such rigid attachment has necessitated the use of an edge inclined at an acute
angle (or at most 45°) to the plane of the fabric, or if a more obtuse angle was used,
the edge has obstructed the feed, as explained above in connection with Figure 3.
The use of guides to prevent the knife from moving in an arc, adds greatly to the
friction and in the limited space about the stitch forming mechanism, such complica-
tion of parts is undesirable."
While these elements of operation seem, to the careless observer, trifling, they
become serious when the machine is run, as in present practice at the rate of 2500
or 3000 revolutions per minute.
In our improved trimmer, the use of a very obtusely inclined edge is permitted,
upon a driving mechanism of the simplest and strongest construction, without
impeding the feed movement.
The other features of improvement which relate to the removal of the knife, and its
adjustment towards and from the needle bave already been described.
We do not claim broadly the use of a knife with an inclined edge, nor the mounting
of the knife upon a lever arm, reciprocated from the driving shaft, save when the
knife is freely suspended from said arm.
Furthermore, we are aware that various devices have been employed for adjusting
the knife towards and from the needle, and that an adjustable plate has been used
with such knives, the edge of said plate forming one edge of the knife slot.
Our adjustable plate P differs from such former devices in that the knife slot is
entirely enclosed by it, and hence does not vary in width with each adjustment of the
plate, as was necessarily the case where the moveable plate formed only one edge of
the slot. The wide slot nade by moving the old forms of plate from the needle, not
only permitted the pushing down of dirt and sometimes of the fabric itself, below the
cloth plate, but with a freely suspended knife would endanger the knife itself, by
allowing it to play laterally.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is :-
-
1. The combination with the stitch-forming mechanism, of a pivoted lever arm
arranged to oscillate in a vertical plane, a knife having an inclined edge, freely
suspended from said lever arm and extending down through the work plate, and
driving mechanism for said lever arm, substantially as set forth.
2. The combination, with the lever arm K having a slot d in its front end, of the
knife L, pin 6 having a grooved neck and the spring g bearing against said pin,
substantially as set forth.
3. The combination of the lever arm K having a lateral adjustable portion, the
knife L suspended therefrom and the laterally adjustable plate P entirely enclosing
the knife slot substantially as set forth.
Dated this 6th day of Sentembar 1887
CARPMAEL & Co.,
Agents for the Applicants.