US239983A - Trimming attachment for sewing-machines - Google Patents

Description

(N 0 Model.)

. -T. 0. ROBIN-SON. Trimmjng Attachment for SewingMachi ne's. No. 239,983.

Patented April" 12, I881.

Am Mi/M.

.UNITED. STATES PATENT OFFicE.

THOMAS C. ROBINSON,'OF OAMBRIDGEPORT, ASSIGNOR TO CHAS. H. OURRIEB, OF BOSTON, MASSACHUSETTS.

TRIMMING ATTACHMENT FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No, 239,983, dated April 12, 1881.

Application filed April 24, 1880. (No model.)

To all whom it may concern:

Be it known that I, THOMAS UROCKER ROB- INsON, of Gambridgeport,*Middlesex county, State of Massachusetts, have invented a new and Improved Trimming Attachment for Sewing-Machines, for trimming the edges of cloth andleather whilein process of sewing, of which the following is a specification.

This invention relates to certain features of construction, which will be described in the specification, and then pointed out in the claims. r

In the accompanying drawings, Figure 1 is a front View of my device attached to a sewing-machine. Fig. 2 is an end view of the same. Fig. 3 is a view, from above, of the throat-plate of the sewing-machine as altered to adapt it to my purpose.

In the drawings only those parts of the sewin g-machine which are essential to the understanding of my device are shown.

In Fig. 1, A is the arm of the sewing-machine. B is the needle-bar lever, connected, in practice, in the usual manner, (the oonnection is not shown in the drawings,) with the needle-bar 0, Figs. 1 and 2, which it operates.

1), Fig. is'a link formed of a bar or strip of metal attached at its lower end to the needlebar .lever by means of a screw, on which it plays loosely, and projecting perpendicularly upward, and loosely connected by a rivet with the end of lever E, which is called the knifebar lover. The left-hand end (in Fig. 1) of the last-named lever is attached by a loose rivet to the upper end of a short strip of metal, F, whose lower end is connected in the same manner to the upper end of a stationary arm, G, which is firmly fixed-to the upper one of the projections forming the head of the sewingmachine, which are attached to the left-hand end of the arm A and support and guide the needle-bar O and .presser-bar G". The knifebar lever E is formed with a collar at or near its middle, that is provided with a thumb-screw, H, Figs. 1 and 2, which, by screwing in, holds to its place a round rod, J, called the knifebar, that passes through the hole in the collar and down through "both of the projections from the arm A, and bears at its lower end, screwed to its side, a strip of steel, K, Figs. 1 and 2,

called the knife. The lower end of this strip K is sharpened to an edge, thus forming a cuttin g-blade, except a portion of the width of the strip which is not sharpened, but continued downward a short distance, (say three-eighths of an inch in practice,) and is drawn at the lower end nearly to a point. I call this portion the lance. This knife K is seen in Fig.2 to be bent to the right diagonally, midway of its length, and then to proceed downward, so that the lower half runs parallel to and close by the side of the needle, at any desirable distance therefrom, as hereinafter explained. Its cutting-edge works as the upper half of a pair of shears, the lower half of the shears being the hardened side of the slot in the throatplate. (Seen in Fig. 3.)

L, Fig. l, is a collar or short cylinder enveloping the knife-bar and held to it at pleasure by a set-screw, M, Fig. 1. This collar L bears at its lower end a projection toward theleft, as shown in Fig. l, which projection carries a small pin, M", projecting perpendicularly downward, and passing into a cylindricalaperture, in which it fits, in the upper projection of the sewing-machine arm A, and in which it moves loosely.

Fig. 3 shows the needle throat-plate commonly used in sewing-machines.

The view, taken from above, shows the toothed top of the feed device, and to the right of this the aperture for the passage of the needle, and to the right of this a small plate, N,

called the knife-plate, of shape as seen, and held in its place by the set-screw P. The lefthand upper corner of this knife-plate is seen to be cut away, leaving a slot between it and the side of the needle throat-plate. Through the wider portion of this slot passes the lance of the knife K, which lance does not quit the slot as the knife moves up and down, and so acts as a guide to the knife and holds it to its direct downward course through the slot.

The operation of the invention is as follows: The sewing-machine being in the act of sewing, the depression of the needle-bar lever B draws down the bar D, and thus the knife-bar lever E, andthe thumb-screw H being tightened-the knife-bar J. The knife K, impinging on the side of the slot described in the needle cessity of putting the several products in the hands of another operator to trim the edges, and guaranteeing a positive uniformity in the distance between the edge of the article operated on and the stitch which the sewing.

machine puts into it. It is sometimes desirable to'increase the distance between the line of the stitches and the edge of the article operated on. To do this I first unscrew the screw P, Fig. 3, and press the upper end (in Fig. 3) of the knife-plate N to the right as far as is desirable, fastening it again, after adjusting my knife K, by screwing up the screw P. 1 then, unscrewing the screws H and M, Figs. 1 and 2, turn the knife-bar J on its own center till the knife Kis at the desired distance from the needle (not shown) of the sewing'machine. Then, tightening the screws H and M and adjusting and fastening the knife-plate N, I have, as the whole device operates, the distance I desire between the line of the sewing and the edge of the substance operated on.

The knife K, of course, wears away by sharpening; but by means of the collar bearing it, and the screws H and M, I let the knife-bar J down as required, thus compensating for the diminution in length. The special advantage of my knife-plate N and its capacity of adjustment is this: In practice it is essential, in a machine having the object of this, thatit should be'possible to increase and diminish the distance of the line of sewing from the line of the edge of the fabric, as different widths are required for different fabrics or different work.

For this purpose it is indispensable, of course, that the slot through which the lance of the knife K (and to a slight distance the edge of the knife itself) passes should have sufficient width to allow the passage. But if the noncutting side of the knife K has not in very close proximity to it a plate or other object to support the fabric operated on, the cut-off portion of the fabric would be almost sure to be carried down by the downward stroke of the knife, get wedged in between the knife and the side of the plate, and after a few cuts stop the machine, and thus make it practically useless. But with my facility of adjusting my knife-plate I can place its left-hand edge (in Fig. 1) just so far fromthe line of the downward course of the knife as that the right-hand side of the knife will pass the knife-plate, and no more, leaving no room for the passage of the cut-off portions of the fabric operated on.

I claim- 1. Theadjustableknife-barandknife,incombination with the knife-bar lever E, provided with the collar, the thumb-screw H, the bearing-arm G, the link F, and the link D, adapted to be attached to the needle-actuating lever, all constructed and arranged substantially as described and shown.

2. The adjustable knife-plate, in combination with the knife, the knife-bar, the collar L and its screw M, the lever E, having the collar, set-screw H, link F, arm G, adapted to be connected with the head of a sewing-machine, and the link D, adapted to be connected with the needle-actuating lever, all constructed and arranged substantially as described and shown.

THOMAS OROOKER ROBINSON.

Witnesses:

LEMUEL P. JENKS, FRED. W. BROWN.

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