Improvements in Sewing Machine Trimmers.
Year: 1898

page_text: Date of Application, 14th Dec., 1893-Accepted, 1st Apr., 1899
[Communicated from abroad by THE SINGER MANUFACTURING COMPANY, of New
York, United States of America, Sewing Machine Manufacturers].
Improvements in Sewing Machine Trimmers.
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 that class of sewing machine trimmers adapted to
trim off the edge of the lower of two pieces of material being sewed together
simultaneously with the stitching operation, by means of a knife or cutter formed
at the end and on the lower side of a suitable shank which may be integral with or
suitably secured to a horizontally swinging lever; the object of the present inven-
tion being to provide a simple and effective trimmer, of the class referred to,
adapted for operation in connection with well-known styles of sewing machines
at present in use, with but little change in the construction of such machines.
To this end the improved trimmer comprises an operating lever pivotally mounted
on an extension of the machine throat-plate and provided with a depending yoke
embracing a trimmer-operating cam with which the shuttle or loop-taker operating
shaft of the machine is provided; a cutter-lever being detachably connected with
said operating lever in such a manner as to reciprocate therewith when the
trimmer is in operation, and the detachable connection of said cutter-lever with
said operating lever permitting the cutter-lever to be swung aside out of the way
when the machine is to sew without trimming.
In the accompanying drawings Fig. 1 is a sectional side view of a portion of a
Singer oscillating shuttle sewing machine with the improved trimmer applied
thereto, the section being taken on line 1-1 of Fig. 2. Fig. 2 is a partial plan
view of the bed-plate of the same machine with the trimmer in place. Fig. 3 is
a front end view of the trimmer, with the shuttle-shaft and trimmer-operating cam
in section. Fig. 4 is a detail end view of the knife and its carrying lever, and
Fig. 5 is a bottom view of the knife and a part of its carrying lever. Fig. 6 is a
plan view of the turret of the attachment and Fig. 7 a section of the turret on
line 7-7 of Fig. 6, this view showing the locking lever in section and a part of
the cutter-lever in side elevation. Figs. 8 and 9 (Sheet 2) are plan and side views,
respectively, of a slightly different form of the invention from that shown on
Sheet 1.
A denotes the sewing machine bed-plate or work-plate and B a special trimmer
throat-plate removably attached by screws to said bed-plate and provided with an
extension b, said special throat-plate fitting in the recess in the bed-plate usually
occupied by the ordinary throat-plate, and said extension plate serving to support
he trimming attachment. C is an operating lever pivotally mounted on a
boss d of a screw d', said lever having a depending yoke c extending downward
hrough an opening a in the bed-plate and embracing a cam e with which the
ocking shuttle operating shaft E is provided, said cam being herein shown as
eing integral with the collar of the shuttle driver 2. The head d² of the
crew d is seated in a recess formed for its reception in the underside of the
xtension 6 of the throat-plate B, the threaded part of said screw entering a

page_text: tapped hole in the lower part of a turret f seated in a circular recess in the hub
of the lever C, said turret being provided with cheeks f¹ between which is
pivotally mounted, on a pin f2, the cutter-lever G carrying at its forward end the
knife or cutter g which is preferably formed on a shank g¹ attached to said lever
by a screw gThe hole in said lever through which the shank of said screw g²
passes is preferably slightly elongated to permit of a limited endwise adjustment
of said shank relative to said lever.
H is a locking lever pivoted on the pin fand provided at its forward end with
a lugh normally held in a notch or recess in the operating lever C by a spring h¹
tending to force the forward end of said locking lever downward, said locking lever
thus locking the turret f and cutter-lever G to the operating lever, so that the
said cutter lever and operating. lever will vibrate in unison when the cutter is to
work; but when the machine is to sew without trimming the tail-piece of the
locking lever will be pressed upon by the attendant, thereby, withdrawing the
lug h from its holding notch c¹ and permitting the turret to be partially rotated to
swing the cutter-lever aside to the position denoted by dotted lines in Fig. 2 when.
the lug h will drop into a notch i formed in a rib with which the throat-plate
extension is provided. When the parts are in this inoperative position. the..
operating lever will continue to vibrate idly, when the machine is running, but
the cutter-lever, turret and locking, lever will be at rest.
The throat-plate B-is provided with a recess 6¹ to receive the cutter and the. strip
of leather or other material which is severed from the work by the cutter, the
latter working against or in close proximity to the front wall of said recess- and
being timed to perform its cutting movements when the needle is in the work,
so that the latter is held immovable while being trimmed. The forward end of
the cutter lever and the cutter attached thereto are held downward by a
U-spring kone arm of which presses against the under side of said lever rearward
of the pivot-pin f2, the resilience of said spring permitting the cutter-lever and
cutter to adapt themselves to varying thicknesses of material.
The cutter-lever is preferably provided with a guide m for the edge of the
upper layer of material, said guide being, adjustably secured to said lever-by
the cutter-attaching screw g².
In the modified form of the invention shown in Figs. 8 and 9 the operating
lever C is provided on its upper side with a lug c entering a recess ³ formed
for its reception in the cutter-lever G¹ the forward end of which latter is pressed
down, to hold the parts engaged, by the spring h³ which will yield when the tail-
piece of said lever G¹ is pressed upon to disengage the said levers, and the lever G
may then be swung aside, as denoted by dotted lines in Fig. 8 until it rests in
the notch of the rib on the throat-plate extension 6, when the machine is to sew
without trimming.
From the foregoing it will be apparent that in order to change a well-known
type' of sewing machine, as now constructed, to a sewing and trimming machine, it
is only necessary to add a cam to the shuttle-operating shaft and to substitute
the modified or extended throat-plate, with the trimmer attachment thereon,
for the ordinary throat-plate.
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. A sewing machine trimming attachment comprising the combination with a
supporting plate adapted to be removably attached to the work-plate of the
machine, of an operating lever pivotally mounted on said supporting plate and
provided with a depending yoke, a horizontally swinging cutter-carrying lever also
pivotally mounted on said plate, and means for detachably connecting said levers
so that the cutter-lever may be swung aside when not in use.
2. A sewing machine trimming attachment comprising the combination with a
supporting plate, of an operating lever pivotally mounted thereon and provided

page_text: with a depending yoke, a horizontally swinging cutter-carrying lever, a pivoted
turret in which said cutter-carrying lever is mounted, and means for detachably
connecting said turret and cutter-carrying lever with said operating lever so that
they will all swing in unison, but permitting the cutter-carrying lever and turret
to be turned aside when the cutter is to be thrown out of operation.
3. A sewing machine trimming attachment comprising the combination with
a supporting plate, of an operating lever pivotally mounted thereon and provided
with a depending yoke, a horizontally swinging cutter-carrying lever, and a spring-
pressed locking lever serving to detachably connect the said cutter-carrying lever
with said operating lever, but permitting said levers to be disengaged from each
other so that the cutter-carrying lever may be swung aside when not wanted for
use.
4. In a sewing and trimming machine, the combination with a rotary or oscilla-
tory shaft located beneath the work-plate of the machine and provided with a cam.
of a trimming attachment comprising a supporting plate located above said
work-plate, an operating lever also above said work-plate and provided with a
depending yoke embracing said cam, a cutter-carrying lever, and means for
detachably connecting said levers so that the cutter-lever may be operated when
desired, but may be swung aside when not in use.
5. The combination with the work-plate A, of the shaft E provided with a
cam e, the supporting plate B located above said work-plate, the operating lever C
also above said work-plate and having the depending yoke c embracing said cam,
the cutter-lever G provided with the cutter g, and means for detachably connecting
said cutter-lever and said operating-lever, so that the former will be actuated by the
latter when desired, but may be detached from said operating lever and swung
aside when not in use.
6. The combination with the shaft E provided with the cam e, of the operating
lever Chaving the depending yoke c embracing said cam, the turret f, a cutter-
lever pivoted in said turret and provided at its forward end with the knife or
cutter g, and means for detachably connecting said cutter-lever with said operating
lever.
7. The combination with the shaft E provided with the cam e, of the operating
lever C having the depending yoke c embracing said cam, the turret f, the cutter-
lever G pivoted in said turret and provided at its forward end with the knife or
cutter g, and the spring-pressed locking lever H pivoted in said turret and serving
to connect said cutter-lever and turret with said operating lever, so that these
parts will all move in unison.
8. A trimming attachment for sewing machines comprising the combination
with a supporting plate, as 6, of an operating lever C pivotally mounted on said
plate and provided with a depending yoke c, the turret f. the cutter-lever G
pivotally mounted in said turret and provided at its forward end with the knife
or cutter g, the U-spring k one arm of which bears upon the under side of said
cutter lever rearwardly of its pivot to press the forward end of said lever vield-
ingly downward, the locking lever H also pivotally mounted in said turret and
having a lug h at its forward end, and the spring h¹ serving to hold said lug in
engagement with the said operating lever, but permitting the said locking lever
to be disengaged from the said operating lever when the cutter-lever is to be swung
aside.
WALLACE FAIRWEATHER.
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents, 62, Saint Vincent Street, Glasgow,
Agent for the Applicant.