Year: 1899

page_text: [Communicated from abroad by THE SINGER MANUFACTURING COMPANY, of New
York, United States of America, Sewing Machine Manufacturers.]
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 ascer-
tained in and by the following statement:-
-
This invention has for its object to provide an improved sewing machine trim-
ming device by means of which the projecting edge of the lower layer of two super-
posed pieces of material may be trimmed off, parallel with the seam, close to the
edge of the upper layer and simultaneously with the sewing operation; the trim-
ming knife being so arranged and operated that it will make undercutting strokes
so that the under side of the lower layer or piece of material of the finished work
will be slightly within the edge of the upper layer thereof. The improved trim-
ming device is more particularly intended for use in shoe work, as in trimming off
the projecting edges of the linings of the lacing flies or shoe tops in which the
outer or upper layers have their edges turned in next to the linings and pasted
down, forming finished edges beyond which the edges of the linings project as the
parts are superposed for sewing, so that the edges of the trimmed-off linings are
somewhat raw or unfinished. It is desirable that these raw or unfinished edges in
the work should be slightly within or under the turned-in finished edges, so as to be
concealed by the latter, and this desideratum is effected in the present invention
by an under-cutting trimming knife.
In carrying the invention into effect the reciprocating trimming blade or knife
is arranged and reciprocated in an inclined position relative to a vertical plane
and sidewise relative to the seam, said knife being preferably provided with a bent
steadying or guiding finger extending below the cutting edge of the knife and
entering a hole in the throat-plate. The knife, which is preferably a thin elastic
steel blade, is preferably attached to a pivoted or tilting block carried by a stock
or small bracket secured to the lower end of the trimming-bar in such a manner
that the cutting edge of the knife will be caused to describe a curved path as it
travels up and down, so that the lower face of the layer of material being trimmed
will be cut farther in under the finished edge of the upper layer than would be
possible if the cutting edge of the knife reciprocated in a right-line path inclined
relative to the path of the needle. Instead, however, of attaching the knife to a
tilting or rocking block the cutting edge of the knife may be caused to travel in

page_text: a curved path simply by the engagement of the projecting bent finger on the
knife with the throat-plate, the thin steel knife-blade having sufficient elasticity
so that it will spring enough to effect this result. The work is guided to the
needle and trimming knife by a guide or gauge against the guiding face of which
the finished edge of the upper layer of material is held by the attendant, so that
the line of stitching and line of trimming will always have a certain relation to the
said finished edge of the upper layer of material.
In the drawings Fig. 1 is a front end elevation of the upper part of a sewing
machine with the improved trimmer applied thereto, the face-plate being removed,
and Fig. 2 is a sectional side view of the same. Fig. 3 is a plan view of the
throat-plate and one form of guide, and Fig. 4 a sectional view of the latter on
line y-y of Fig. 3. Fig. 5 is a cross section of the throat-plate on line æ― of
Fig. 3. Fig. 6 is a detail side view of the knife and its carrier. Fig. 7 is a
broken out plan view of the form of guide preferably employed. Fig. 8 is a
detail view illustrating
a slight modification and Fig. 9 is a detail sectional view
illustrative of the work.
A denotes the head or front end portion of the bracket-arm of a sewing machine,
'B the driving shaft and C the needle-bar connected to a crank at the front end of
said shaft by a pitman c. D is the trimmer-bar connected by a spring-pressed
pin d to an arm d' of a short rock-shaft d² having a second arm d³ formed to
embraco an operating eccentric b on the shaft B, this trimmer-bar
operating-mechanism being of well-known construction." E is the knife-
carrier secured to the lower end of the trimmer-bar ), and e is the knife
which is preferably connected with said carrier by a block pivotally attached
to said carrier by a pin e³. The knife e is preferably provided with a bent depend-
ing finger which enters a hole f in the throat-plate f¹, the said knife being
attached to the pivoted block e² by screws e and a clamping plate e. The rear
face of the carrier E with which the block is in contact is of different form
from the contiguous face of said block, so that the latter may have a limited rock-
ing movement on the said face; a spring e normally holding said block_in the
position shown in Figs. 2 and 6, but said spring yielding under pressure to permit
the block to rock.
The right or rear face of the bent finger e¹ on the knife normally presses against
the top of the right or rear wall of the slot f in the throat-plate (the front or left
wall of said slot being inclined, as shown in Fig. 5) so that as the knife descends
the pressure of said finger against the throat-plate will rock the block e slightly
on its pivot pin, (compressing the spring e) and thus cause the cutting edge of
the knife to describe a curved path as it descends and which, if continued far
enough down, would intersect the plane of the path of the needle, thus giving
a more pronounced under-cut than would result if the edge of the knife travelled
simply in a right-line inclined path. This right or rear wall of the slot f is
preferably formed by a spring-pressed or yielding plate which will insure a
proper cutting action but which will yield under sufficient pressure and thus avoid
breakage. The inclined elastic knife blade, with its bent finger, would spring
enough to effect this result were it directly attached to the carrier E (as shown in
Fig. 8) but it is better to connect the knife with the carrier through the pivoted
block as there is less friction and less danger of breaking the knife.
The work guide is formed at the forward end of a shank G which is preferably
attached to an adjustable plate g, but which may be integral with said plate, said
guide comprising the overhanging lip gl, which is to rest on the top of the layer
of fabric, and the vertical guiding face or wall g² against which the edge
of the said upper layer will rest to properly guide the work to the
needle and trimming knife. Said guide also preferably comprises the slender
finger g³ close to the outer or left face of which the needle descends and close to the
inner face of which the cutting edge of the knife descends. The plate gis
adjustably secured by a screw g to a base-plate g which is fixed to the work-
plate of the machine, as by screws 98, the lateral position of the plate g and of

page_text: the guide connected therewith determining the distance of the stitches from the
edge of the work. The guide is supported above the throat-plate f¹ far enough
to permit the edge of the lower layer of material which is to be trimmed off to
pass beneath it, said guide being vertically adjustable, to accommodate different
thicknesses of material, of either or both layers, by means of the screw h² impinging
against the plate g, the plate g springing enough to permit of this adjustment.
To throw the trimmer-bar out of action it is only necessary to withdraw the
spring-pressed locking pin d from its engaging notch d in the trimmer-bar D
when the spring will lift the said bar so that the knife will be out of the way
of the work. At such times it is frequently desirable that the work-guide should
also be removed so that the attendant can direct the work to the needle indepen-
dently of said guide. To this end the guide-carrying plate g is preferably con-
nected with the base-plate g by a spring-pressed locking-slide g so that when
said locking-slide is withdrawn from its engaging notch in said plate g the latter
will be thrown to the right out of the way by a retracting spring 96 provided for
this purpose.
As I believe that I am the first to construct a sewing machine trimming device
in which a reciprocating trimming knife is inclined relative to a vertical plane
and sidewise to the seam, or to the direction of the feed of the work, and is recipro-
cated in the direction of its length in this position so as to be adapted to trim
off, with undercutting strokes, the projecting edge of the lower layer of two
superposed pieces of material simultaneously with the sewing operation and so as
to leave the cut edge of the lower layer h of the work slightly within the uncut
edge of the upper layer of the work, I do not wish to be understood as limiting
my invention to the details herein shown and described, as these may be varied
widely without departing from the essence of the invention.
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 sewing machine, the combination with a vertically reciprocating needle,
of a trimming knife which is inclined relative to a vertical plane and sidewise
to the seam, or the direction of the feed of the work, and means for reciprocating
the said knife in the direction of its length; whereby the edge of the lower layer
of two superposed pieces of material being sewed together may be trimmed off
within the edge of the upper layer.
2. In a sewing machine, the combination with a vertically reciprocating trimmer-
bar, of a pivoted block connected therewith, a knife attached to said block and
which is inclined relative to a vertical plane and means for causing said block
to rock or tilt as the said bar is reciprocated, thereby giving an undercutting
action to the edge of the said inclined knife.
3. In a sewing machine, the combination with a trimming knife which is
inclined relative to a vertical plane and sidewise to the seam, and means for recipro-
cating said knife in the direction of its length to under-cut the lower of two
superposed pieces of material, of a guide supported above the work-plate so as to
guide the edge of the upper layer of two superposed pieces of material, while
permitting the projecting edge of the lower layer to pass beneath it, said guide
having a vertical guiding wall and, at its extreme end, an overhanging lip g
above said wall, and means for adjusting said guide vertically to accommodate
materials of different thicknesses.
4. In a sewing machine, the combination with an inclined, reciprocating trim-
ming knife having a depending bent finger projecting below the cutting edge of
said knife, of a throat-plate having a hole or slot for receiving said finger and
which latter, by its contact with the wall or walls of said slot, will cause said
cutting edge to travel in a curved path.
5. In a sewing machine, the combination with a reciprocating trimming knife
which is inclined relative to a vertical plane and sidewise to the seam, of means

page_text: for reciprocating said knife in the direction of its length, and guiding means for
causing the cutting edge of said knife to travel in a curved path as it is
reciprocated.
Dated this 7th day of February 1899.
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents, 62, Saint Vincent Street, Glasgow,
Agent for the Applicant.