US2161527A - Blind stitch sewing machine - Google Patents

Description

June 6, 1939.

C. W. MUELLER BLIND STITCH SEWING MACHINE Filed June 19, 1937 9 Sheets-Sheet l I N VEN TOR Ck ar/es l4. Mueller BY 1 ATTORNEY June 6, 1939. c. w. MUELLER 2,161,527

BLIND STITCH SEWING MACHINE Filed June 19, 1957 9 Sheets-Sheet 2 June 6, 1939. c; w MUELLER 2,161,527

BLIND STITCH SEWING MACHINE Filed June 19, 1937 9 Sheets-Sheet 3 Char/es "(Mae/lav June 6, 1939. c. w. MUELLER 2,161,527

BLIND STITCH SEWING MACHINE Filed June 19, 1937 9 Sheets-Sheet 4 June 6, 1939. c w MUELLER 2,161,527

BLIND STITCH SEWING MACHINE Filed June 19, 1957 9 Sheets-Sheet 5 CharZes I4. Mae/la)" June 6, 1939. M L R 2,161,527

BLIND STITCH SEWING MACHINE Filed June 19, 1957 9 Sheets-Sheet 6 gmwcnkvn Char/es W Muel/er June 6, 1939. c w L R 2,161,527

BLIND STITCH SEWING MACHINE Filed June 19, 1937 9 Sheets-Sheet 8 Char/es W Muel/er June 6, 1939. c. w. MUELLER BLIND STITCH SEWING MACHINE Filed June 19, 1957 9 Sheets-Sheet 9 gvwc/wkvb Char/es )4. Ma q//er Patented June 6, 1939 UNITED STATES PATENT OFFICE BLIND STITCH SEWING MiCI-IINE Application June 19, 1937, Serial No. 149,258

17 Claims.

This invention relates to new and useful improvements in sewing machines generally, although more particularly to sewing machines of the blind stitch type.

In blind stitch sewing machines, such as is shown in each of my prior Patents 1,989,602, Jan. 29, 1935 and 2,018,186, Oct. 22, 1935, the reciprocatory ridge forming element is mounted directlybelow the needle on a work support which m is fulcrumed on a horizontal pivot located in rear of the needle path. The ridge forming element which in one form is a disc, is provided with relatively low and high peripheral portions which are alternately positioned in cooperative s relation with the needle to form resultant anchor and skip stitches. The driving connections between the main shaft and the oscillatory shaft which is journaled on the work support and which reciprocates the ridge forming element, is such that when a seam or extremely thick layers of fabrics are fed over the element, the work support will be depressed and the driving connections will cause the oscillatory shaft to rock and thereby shift the ridge forming element out of its true cooperative relation with the needle with the result that one or more stitches will be improperly positioned in the fabric or fabrics.

One of the important objects of this invention is to provide driving connections between the main shaft and the reciprocatory ridge forming element operating shaft whereby the element will remain in its true cooperative relation with the needle when the pivoted work support is depressed 5 and thereby insure the proper positioning of the stitches in the fabric or fabrics.

Another object of the invention is to provide a main frame which includes a standard, a laterally extending upper arm and a forwardly and (m downwardly inclined arm, a reciprocatory needle and a presser foot mounted on the front end of the forwardly extending arm, and a work support which is fulcrumed on a horizontal pivot located in front of the needle path, whereby the 45 presser foot will remain at the same height relative to the operator and yet afford increased room under the laterally extending arm for the passage of work when the work is being fed rearwardly and also when the work is being removed 50 from the machine upon depression of the pivoted work support. 1

A further object of the invention is to provide a work clamp which cooperates with the presser foot and which comprises two independently mounted sections which are spring pressed upwardly for alternate cooperation with a top feed dog and the presser foot, together with means for varying the relative pressures of the sections against the foot, whereby a body fabric and an overlying hem fold may be fed properly.

A still further object of the invention is to provide a folder support which is mounted on the main frame in front of the work support to swing about a vertical pivot whenever it is desired to shift the folder support out of operative position and to provide means for elevating the same during said swinging movement to insure the folder clearing the upper surface of the work support.

With these and other objects in view which will more fully appear, the nature of the invention will be more clearly understood by following the description, the appended claims, and the several views illustrated in the accompanying drawings.

In the drawings:

Figure 1 is a top plan View of a machine constructed in accordance with my invention,

Figure 2 is a right hand elevation thereof, the standard being shown in section,

Figure 3 is a front elevation thereof, the folder being omitted,

Figure 4 is a left end elevation thereof,

Figure 5 is a bottom plan View of the machine,

Figure 6 is an enlargedfragmentary-vertical section taken through the base and work support substantially in the plane of oscillation of the needle,

Figure 7 is an enlarged detail section showing a slight depression of the work support relative to the needle,

Figure 8 is an enlarged vertical section showing the work support in its locked or normal position,

Figure 9 is a similar view but showing the work support in its unlocked or fully depressed position,

Figure 10 is a view showing the driving connections between the main shaft and the oscillatory shaft which operates the ridge forming element, the View indicating the limits of the oscillatory movements of the element when forming all anchor stitches,

Figure 10 is a View showing the corresponding position of the control lever,

Figure 11 is a view similar to Figure 10 but showing the limits of oscillatory movements of the element when forming alternate anchor and skip stitches,

Figure 11 is a View showing the corresponding position of the control lever,

Figure 12 is a detail side elevation, partly in section, showing the adjustable tensioning means for a work clamp section,

Figure 13 is a perspective view of a portion of the main frame showing the post which supports the work support,

Figure 14 is a perspective view of the left end of the work support,

Figure 15 is a vertical section taken through the pivot of the folder support,

Figure 16 is a plan view of the presser foot and showing the needle, the top feed dog, the ridge forming element, and the work clamp, and

Figure 17 is a top plan view of the left end of the work support showing the ridge forming element, the operating shaft therefor, and the work clamp.

Like reference numerals designate corresponding parts throughout the several figures of the drawings.

The sewing machine includes a main frame A which comprises a base 5, a standard 6, an arm I which extends laterally from the upper end of the standard and terminates in a forwardly extending arm 8 which is inclined downwardly and forwardly relative to the base, and a post 9 which is integral with the base and is located at the front thereof and at the right of the arm 8, the post being inclined forwardly and having its upper portion disposed in a vertical plane in front of the front end of the arm 8 and in a horizontal plane below said front end of said arm.

Rigidly fixed to the forward or free end of the arm 8, is a horizontal presser foot B having a centrally located longitudinal opening or slot I formed therein, the foot being forwardly and downwardly inclined in a plane disposed in parallelism to the major axis of said arm 8.

Journaled in the upper end of the standard 6 and in the arm I is a main shaft I I, and journaled in the arm 8 and extending longitudinally thereof is an oscillatory needle shaft I2 having a needle arm I3 fixed to its front end. The needle shaft I2 is located directly above the presser foot opening Ill and has its longitudinal axis in a downwardly and forwardly inclined plane disposed in parallelism with the presser foot. Attached to the needle a-rm I3 is a curved needle I4 which reciprocates across the opening ID of the foot. The needle shaft I2 is oscillated from the main shaft II by connections such as is shown in my prior Patent 2,018,186 referred to above. A looper or spreader I5 cooperates with the needle I4 in the usual manner to form single thread chain stitches, although any other type of complemental stitch forming mechanism may be employed if desired. The looper I5 is fixed to a looper rod I6 which is fulcrumed on a depending arm I! pivoted on a horizontal pin I8 mounted in the arm 8 and the looper rod is driven from the main shaft II by the usual connections.

A work support C is clamped by'screws I9 to a horizontal pivot shaft journaled in spaced bearings 2|, 2| formed in the post 9 of the main frame. It will be noted that the pivot shaft 20 is disposed in a plane parallel to the main shaft II and that said pivot shaft is located considerably in front of the needle I4 as well as in front of the presser foot 13. This work support C has its left end reduced to form a horn 22 and projecting laterally from the outer end of the horn is a rectangular frame 23 having an open top and bottom. This frame 23 is located directly under the presser foot B and includes front and rear walls 24, 25 and an end wall 26.

Operating in the presser foot opening II) for intermittently projecting a node of fabric upwardly into needle penetrating position, is a ridge forming element D which in this instance consists of a disc fixed to an operating shaft 21 which is journaled at the end in screw bearings 28, 29, the screw bearing 28 being mounted in an opening 30 formed in the end wall 26 of the frame 23 and the screw bearing 29 being mounted in an opening 3| formed in a lug 32 which depends from the under side of the Work support C. The oscillatory operating shaft 27 is disposed in a horizontal plane in parallelism not only with the main shaft II but also with the pivot shaft 20 of the work support. It will, therefore, be seen that the work support C extends rearwardly from the pivot shaft 23 to a point under the presser foot B and that this work support is capable of swinging downwardly away from the presser foot or upwardly toward the same. It will also be observed that the shaft 21 which operates the ridge forming element D is disposed in rear of the pivot shaft 20 and is movable upwardly and downwardly with the work support and consequently when the work support is lowered the ridge forming element D will be correspondingly lowered with respect to the path of the needle. The ridgeforming disc D is formed with a concentric periphery 33 and with a radial front edge 34, and a recess 35 is formed at their juncture, the recess forming a resultant step 36. It will be observed that the concentric edge 33 and the step 36 form peripheral surfaces or portions of different radii which are arranged in tandem, the portion 33 constituting a high portion and the step 36 constituting a low portion. When the high portion 33 is positioned under the needle the latter will form resultant anchor stitches in the fabric or fabrics and when the low portion 36 is positioned below the needle, the latter will form skip stitches in the fabric or fabrics. In other words, the eifective depth of needle penetration in the fabric or fabrics is constant when the high portion 33 is positioned below the needle but when the low portion 36 is positioned below the needle the depth of needle penetration will be decreased, as fully explained in my prior Patent 2,018,186 referred to above.

An upwardly spring pressed work clamp E is mounted on the work support C for alternate cooperation with presser foot B and a 4-motion top feed dog 13. The top feed dog F operates in the opening I3 of the presser foot B and is supported on the frame arm 8 and is operatively connected to the main shaft 5! in the usual manner. This feed dog operates in rear of the needle path and cooperates with the work clamp E to intermittently feed the fabric rearwardly when the needle is out of said fabric. The work clamp E cooperates with the bottom of the foot B to clamp the fabric therebetween during the idle motions of the feed dog F whereby said fabric will be held against the thrusts of the needle.

The work clamp E includes two separate clamping sections 31, 3'! which are dipsosed side by side and extend longitudinally of the presser foot from a point in front of the needle path to a point well in rear thereof, the front portions of the sections being recessed to receive the ridge forming disc D and the rear portions of said sections being disposed in close relation below the presser foot opening I8 whereby the feed dog F will cooperate with both sections. The work clamp sections 37 are each pivoted as at 38 on the free end of ahori'zontal arm 39 of a bell crank lever 46, the other arm. 4| of the lever projecting downwardly in front of the front wall 24 of the rectangular frame 23 of the work support. These two levers 40 are arranged side by side and are fulcrumed at their angles on a common pivot shaft 4| which is disposed in parallelism with the disc operating shaft 21 and is mounted in a bearing opening 42 formed in the horn 22 of thework support and secured therein by a set screw 43. Associated with the vertical arm 4| ofeach lever is a coil spring 44, said spring extending through an opening formed in the front wall 24 of said frame 23, the front end of the spring being connected to the lever arm 4| and the rear end of the spring being connected to an adjustable tension screw 46 mounted in the rear wall 25 of said frame 23. These two springs 44 function to yieldably urge the clamping sections 31 upwardly against the presser foot B or top feed dog F. Adjustable stop screws 41, 41 have threadable engagements openings 48, 48 formed in the front wall 24 of the frame 23 directly above the openings 45 for cooperation with the vertical arms 4|, 4| of the bell crank levers 46, 46 and to thereby independently and variably limit the upward movement of the clamping sections 31, 31. 'These independent stops 41, 41 are very important in hemming operations. For instance, in hemming the bottom of a circular-cut skirt, there is considerable fullness in the hem fold, and this: fullness must be gathered in while the work is being fed through the machine. If there is too much spring pressure applied to the right hand clamping section 31 which engages the fabric directly below the hem fold, it becomes very difficult for the operator to retard the base layer slightly in order to allow the top feed to fill or gather in the surplus material. Therefore, by providing the independently adjustable stops 41, 41 the pressure on the clamping sections 31, 31 may be adjusted to suit working conditions. Furthermore, sometimes the above condition is reversed and a lesser pressure on the left hand clamping section 31 will be de sirable.

I The work support C is capable normally of a small free vertical movement about its-pivot 20 to permit not only a variation in the thicknesses of materials being stitched but also to permit seams being fed over the ridge forming disc D. To this end, the work support C is provided with depending integral front and rear walls 49, 50 respectively arranged on opposite sides of the disc operating shaft 21. A head 5| includes a horizontal attaching plate 52 and a depending tubular neck 53 having an open lower end. The head 5| is rigidly attached to the lower edges of the depending walls 49, 50 by screws 54, 54. Mounted in said neck for vertical movements relative thereto is a core or support 55. A limiting screw 56 passes downwardly through a nonthreaded opening 51 formed in the plate 52, the lower end of the screw being threaded into the core and the head 58 of said screw cooperating with the plate 52 to limit the upward movement of the work support C relative to the core 55. The upper surface of the core is normally spaced below the plate 52 and the upper portion of the core is reduced to form a resultantp eripheral recess for receiving a coil spring 59 which engages the bottom wall of the recess and the plate 52 and functions to yieldably retain the work support C against downward movement relative to said core.

Thecore 55 is normally locked against vertical movements, but when the core is moved vertically the work support C, the disc D, and the work clamp E are moved with it. The lower end of the core 55 is provided with a depending lug 66. A toggle is connected to the lug 68 and to the base 5 of the main frame. The toggle includes a bell crank lever 6| which includes an upright arm 62 and a forwardly extending hori-' -zontal arm 63.

The lower end of the arm 62 is fulcrumed on an eccentric 64 which is fixed to a horizontal shaft 65, the latter being disposed below the disc operating shaft 21 and in generally vertical alinement with said shaft 21 and with the needle. The ends of the shaft 65 are journaled in the base 5 below the upper surface thereof. A normally uprightly disposed link 66 is pivotally connected at its upper end by a pin 61 to the lug and at its lower end by a pin 68 to the upper end of the toggle arm 62, the pin 68 being rigidly secured to the link 66 by a set screw 69. A coil spring 10 is disposed around the projecting end of the pin 68, one end of the spring being anchored in a transverse slot 1| formed in the outer end of the pin and the other end of the spring engaging under a stop pin 12 fixed to thelink 66. The spring 16 functions to yieldably retain the toggle elements 62, 66 in their longitudinally alined or locked positions, as shown in Figure 8, and a stop shoulder 13 fixed to the arm 62 cooperates with the stop shoulder 14 on the'bottom of the link 66 in the manner illustrated in Figure 8 to prevent the toggle elements passing beyond their locked positions. It will be noted that the arm 62 and the link 66, when in their normal or locked positions, are in generally vertical or upright alinement, i. e., the pivots 61, 1| and are in alinement in a plane which is slightly inclined to the vertical, or in other words, in a plane at right angles to the plane of the foot B. A chain 15 which is adapted to be connected to a treadle or knee-press, has its upper end connected to the for'wardend of the horizontal arm 63 of said bell crank lever. Thus upon operation of the knee-press or treadle the toggle will be broken and the support or core 55 together with the work support C and parts mounted thereon, will be depressed to permit the ready insertion or withdrawal of the material, and.- upon release of said knee-press or treadle, the parts will be returned to their normal position by the spring 10. It will, therefore, be seen that when the toggle is in its locked or normal position, the work support C is capable of having a slight vertical movement against the tension of the spring 59 so as to permit various thicknesses of fabrics and seams being fed through the machine.

In order to positively adjust the normal vertical I position of the work support C together with the disc D, and thereby set the machine for materials of different thicknesses, I have provided a hand adjusting shaft 16 which is journaled in a bushing 11 mounted in a tubular bearing bracket 18 secured in an opening formed in the front wall of the standard 6. A finger knob 19 is rigidly attached to the front end of the shaft 16 and a spring pressed pin 66 cooperates with the knob to retain the shaft in any position of adjustment. Journaled on the bracket 18 is a worm wheel 8| which is in constant mesh with a worm 82 formed on the inner end of the shaft 16. Journaled in the base 5 is a horizontal rock shaft ,83 having a rock arm 84 fixed to its right hand end, said arm being pivotally connected by a link 85 to the worm gear 8|. The other end of the rock shaft 83 is provided with a rock arm 86 which is pivotally connected to the rear end of a rack bar 8'! which extends forwardly along the base to a point below and in front of the eccentric carrying shaft 65. The rack bar 81 is provided along its upper forward edge with rack teeth 88 which engage the teeth of a pinion 89 fixed on said shaft 65. A disc 90 is journaled on the shaft 65 and is provided with a pin 9I forming a support for the front end of said rack bar. A 0011 spring 92 is connected at one end to the disc 90 and at its other end to the base 5v and functions to urge the pin 9I upwardly whereby the rack bar will be retained yieldably in engagement with the pinion 89. If desired, a coil spring -92 may be provided and attached to the base 5 and the bar 81 as shown in Figure 5 so as to be effective to constantly urge the bar forwardly. It will, therefore, be seen that when the knob "I9 is rotated the rack bar 81 will be moved endwise, the shaft 65 together with the eccentric 64 will be rotated, and the work support will be raised or lowered, depending on the direction of rotation of the knob.

The ridge forming element D is reciprocated from the main shaft II by a train of mechanism including a manual control lever whereby either the high or low portions 33, 36 of the disc or element will be alternately presented to the needle to thereby form alternate anchor and skip stitches in the material or whereby thahighportion 33 only of the disc or element will be successively presented to the needle to thereby form successive anchor stitches in the material. To this end, a bell crank lever 93 is journaled on a horizontal axis 94 in the standard 6 and below the main shaft II. The bell crank lever 93 includes a forwardly extending horizontal arm 95 which is connected by a link 91 to the main .shaft II through the medium of a 2-to-1 reduction gear coupling which is indicated as a whole by the numeral 98 and which is fully shown and described in my prior Patent 1,989,602 referred to above. The bell crank lever 93 includes a depending vertical arm 99 which is pivotally connected as at I to the rear end of a forwardly extending link IN. A horizontal shaft I02 is journaled in a base lug I03 at a point between the pivot shaft 20 of the work support C and the disc operating shaft 21, said shaft I02 being disposed in parallelism with said shafts 20 and 21. Fixed to the right hand end of the shaft I 02 is an eccentric .pin I04 and a lever I05 is journaled intermediate its ends on said eccentric pin. The lower arm I06 of said lever is pivotally connected as at I01 to the forward end of the link IM and the upper arm I08 of said lever is pivotally connected as at I09 to a rearwardly extending link IIO which is pivotally connected at its rear end as at III to a depending rock arm I I2 clamped to'the disc operating shaft 21. Fixed to the left hand end of the eccentric shaft I02 is an upwardly extending rock arm I I3 and pivotally connected to the upper end of said arm as at H4 is a rearwardly extending link I I5, the rear end of said link being pivotally connected as at 'I I6 to the lower end of a manually operable control lever II! which is fulcrumed on the disc operating shaft 21 and has its upper end provided with a finger-piece or knob I-I8 which projects through an opening II9 formed in the work support C. The knob IIO also projects upwardly through a slot I20 formed in a plate I2I mounted on the upper surface of the work support C.

It will be noted that the eccentric pin I04 constitutes a shiftable fulcrum for the lever I05 and that when the shaft I02 is oscillated by the manually control lever II'I said fulcrum will be shifted either forwardly or rearwardly and the disc operating shaft 21 will be angularly shifted thereby, and consequently the disc D will be shifted angularly with respect to the needle path. The driving connections between the main shaft II and the disc operating shaft 27 are such that the disc D will partake of a greater angular movement during alternate rearward strokes thereof and a lesser angular movement during intermediate rearward strokes. Thus when the manually control lever II! is in the position shown in Figure 10 the high peripheral portion 33 of the disc D will be presented to the needle during successive rearward movements of the disc whereby successive anchor stitches will be formed in the fabric; and when the control lever is in the position shown in Figure 11 the high and low peripheral portions 33, 36 will be alternately presented to the needle whereby alternate anchor and skip stitches will be formed in the fabric. It will furthermore be observed that when the work support C is in its normal or locked position said support is capable of having a slight downward movement due to the intermediate spring 59, and that by reason of the lever I 05 being disposed between the pivot shaft of the work support and the disc operating lever 21 together with the link IIO which connects the lever I 05 with the rock arm I'I2, this slight downward movement of the work support will maintain the low peripheral portion 36 of the disc D in proper cooperative relation to the needle path whenever said low portion 36 is positioned in cooperative relation with the needle and consequently the stitches will be properly positioned in the fabric.

As previously stated this machine is particularly adapted for blind stitching heins and therefore I have provided a support G for an adjustable hemmer H. The support G is mounted on the base '5 in front of the work support C and is adapted to swing about a vertical pivot whenever it is desired to dispense with the folder. The support G is provided at its right hand end with a depending bearing lug I22 having a hardened plate I23 attached to its lower end. A forwardly extending bracket arm I24 is attached to the front edge of the base 5 and is provided at its front end with a vertical bore or socket I25 in which is mounted the lower end of a tubular hinge pin I26, said pin being rigidly secured to the bracket arm I24 by set screws I27. The hinge pin I26 project's upwardly into a vertical bore or bearing opening I28 formed in the bearing lug I22. A stop collar I29 is clamped to the hinge pin I26 at a point between the bracket I24 and the'bearing lug I 22. The hinge pin I26 is provided with upper and lower flanged caps I30, I3l which respectively engage the support G and the bracket I24, and a coil spring I32 is disposed within the pin and has its ends connected to said caps for yieldably retaining the folder support G against the stop collar I29. The upper surface of the folder support G is disposed below the forward end of the presser foot B in order to properly position the folder, and consequently the upper surface of the support G is disposed in a horizontal plane below the upper surface of the work support C. The hemmer H includes a base I33 which is attached to the folder support G by screws I34. The left hand section I35 of the folder is laterally adjustable and includes an arm I36 which is shiftable in guides I31, I31 mounted on the base I33, said arm being disposed in parallelism with the disc operating shaft 21. Furthermore, the arm I35 is disposed in a horizontal plane below the upper surface of the work support C as shown in Figure 2, and consequently means are provided for automatically elevating the folder support G when the latter is swung forwardly whereby the right hand end of the arm I36 will be elevated a sufficient distance to clear the upper surface of the work clamp C. To this end, the stop collar I29 is provided with a cam I38 and the plate -I23 which is attached to the bearing lug I22 is provided with a depending cam follower I39 which cooperates with the cam I38 to effect an elevation of the folder support G against the tension of the spring I32. A notch or seat I40 is formed in the upper surface of the stop collar I29 for receiving the cam follower I39 when the folder support G is swung to its inoperative or forward position and thereby frictionally retain said support against accidental swinging movement.

It is of course to be understood that the details of structure and arrangement of parts may be variously changed and modified without departing from the spirit and scope of my invention.

I claim:

1. In a blind stitch sewing machine, the combination with a main frame including a base and a forwardly extending arm disposed in a plane above the base, of a main shaft journaled in the frame, a presser foot fixed to the front end of the arm and provided with an opening, a stitch forming mechanism mounted on the arm and including a needle mounted for reciprocations above the foot and across the opening therein, a horizontal work support mounted on the base to swing upwardly and downwardly relative to the foot and about a horizontal axis located in front of the needle, means for normally retaining the work support yieldably against depression, a reciprocatory ridge forming element operating in the presser foot opening for projecting a ridge of fabric upwardly into needle penetrating position and movable upwardly and downwardly with said work support, an oscillatory shaft journaled on the work support and disposed in parallelism with the axis thereof and operatively connected to said element, and driving connections between the main and oscillatory shafts for operating the latter and including devices for retaining the oscillatory shaft against angular movement upon depression of the work support.

2. In a blind stitch sewing machine, the combination with a main frame including a base and a forwardly extending arm disposed in a plane above the base, of a main shaft journaled in the frame, a presser foot fixed to the front end of the arm and provided with an opening, a stitch forming mechanism mounted on the arm and including a needle mounted for reciprocations above the foot and across the opening therein, a horizontal work support mounted on the base to swing upwardly and downwardly relative to the foot and about a horizontal axis located in front of the needle, means for normally retaining the work support yieldably against depression, an oscillatory ridge forming disc operating in the presser foot opening for projecting a ridge of fabric upwardly into needle penetrating position and movable upwardly and downwardly with said -work support, an oscillatory shaft journaled on the work support and disposed in parallelism with the axis thereof and rigidly connected to said disc, and driving connections between the main and oscillatory shafts for operating the latter and including devices for retaining the oscillatory shaft against angular movement upon depression of the work support.

3. In a blind stitch sewing machine, the combination with a main frame including a base and a forwardly extending arm disposed in a plane above the base, of a main shaft journaled in the frame, a presser foot fixed to the front end of the arm and provided with an opening, a stitch forming mechanism mounted on the arm and including a needle mounted for reciprocations above the foot and across the opening therein, a horizontal work support mounted on the base to swing upwardly and downwardly relative to the foot and about a horizontal axis located in front of the needle, means for normally retaining the work support yieldably against depression, an oscillatory ridge forming disc operating in the presser foot opening for projecting a ridge of fabric upwardly into needle penetrating position and movable upwardly and downwardly with said work support, said disc having high and low peripheral work presenting portions arranged in tandem, an oscillatory shaft journaled on the work support and disposed in parallelism with the axis thereof and rigidly connected to said disc, and driving connections between the main and oscillatory shafts for operating the latter and including devices for retaining the oscillatory shaft against angular movement upon depression of the work support, said driving connections periodically presenting to the needle first one of said disc portions and then the other to thereby vary the effective depths of the needle penetrations.

4. In a blind stitch sewing machine, the combination with a main frame including a base and a forwardly extending arm disposed in a plane above the base, of a main shaft journaled in the frame, a presser foot fixed to the front end of the arm and provided with an opening, a stitch forming mechanism mounted on the arm and including a needle mounted for reciprocations above the foot and across the opening therein, a horizontal work support mounted on the base to swing upwardly and downwardly relative to the foot and about a horizontal axis located in front of the needle, means for normally retaining the work support yieldably against depression, a reciprocatory ridge forming element operating in the presser foot opening for projecting a ridge of fabric upwardly into needle penetrating position and movable upwardly and downwardly with said work support, an oscillatory shaft journaled on the work support and disposed in parallelism with the axis thereof and operatively connected to said element, and driving connections between the main and oscillatory shafts for operating the latter and including devices for retaining the oscillatory shaft against angular movement upon depression of the work support, said devices including a substantially vertical lever fulcrumed on a horizontal axis located intermediate the work support pivot and the oscillatory shaft, a rock arm fixed to the oscillatory shaft, and a link connecting the upper end of the lever and the rock arm.

5. In a blind stitch sewing machine, the combination with a main frame including a base and a forwardly extending arm disposed in a plane above the base, of a main shaft journaled in the frame, a presser foot fixed to the front end of the arm and provided with an opening, a stitch forming mechanism mounted on the arm and including a needle mounted for reciprocations above the foot and across the opening therein, a horizontal work support mounted on the base to swing upwardly and downwardly relative to the foot and about a horizontal axis located in front of the needle, means for normally retaining the work support yieldably against depression, an oscillatory ridge forming disc operating in the presser foot opening for projecting a ridge of fabric upwardly into needle penetrating position and movable upwardly and downwardly with said work support, an oscillatory shaft journaled on the work support and disposed in parallelism with the axis thereof and rigidly connected to said disc, and driving connections between the main and oscillatory shafts for operating the latter and including devices for retaining the oscillatory shaft against angular movement upon depression of the'work support, said devices including a substantially vertical lever fulcrumed on a horizontal axis located intermediate the work support pivot and the oscillatory shaft, a rock arm fixed to the oscillatory shaft, and a link connecting the upper end of the lever and the rock arm.

6. In a blind stitch sewing machine, the combination with a main frame including a base and a forwardly extending arm disposed in a plane above the base, of a main shaft journaled in the frame, a presser foot fixed to the front end of the arm and provided with an opening, a stitch forming mechanism mounted on the arm and including a needle mounted for reciprocations above the foot and across the opening therein, a horizontal work support mounted on the base to swing upwardly and downwardly relative to the foot and about a horizontal axis located in front of the needle, means for normally retaining the work support yieldably against depression, an oscillatory ridge forming disc operating in the presser foot opening for projecting a ridge of fabric upwardly into needle penetrating position and movable upwardly and downwardly with said work support, said disc having high and low peripheral work presenting portions arranged in tandem, an oscillatory shaft journaled on the work support and disposed in parallelism with the axis thereof and rigidly connected to said disc, and driving connections between the main and oscillatory shafts for operating the latter and including devices for retaining the oscillatory shaft against angular movement upon depression of the work support, said driving connections periodically presenting to the needle first one of said disc portions and then the other to thereby vary the effective depths of the needle penetrations, said devices including a substantially vertical lever fulcrumed on a horizintal axis located intermediate the work support pivot and the oscillatory shaft, a rock arm fixed to the oscillatory shaft, and a link connecting the upper end of the lever and the rock arm.

'7. In a blind stitch sewing machine, the combination with a horizontal presser foot having an opening, an intermittent top feed dog operating in said opening, separate work clamp sections located below the foot for alternate cooperation with the feed dog and the foot, separate spring means for pressing said clamp sections upwardly into said cooperative relation with said feed dog and foot, and means for varying the pressure of one of said spring means.

8. In a blind stitch sewing machine, the cormbination with a horizontal presser foot having an opening, an intermittent top feed dog operating in said opening, separate work clamp sections located below the foot for alternate cooperation with the feed dog and the foot, separate spring means for pressing said clamp sections upwardly into said cooperative relation with said feed dog and foot, and separate means for varying independently the pressures of said separate spring means.

9. In a blind stitch sewing machine, the combination with a horizontal presser f'oot having an opening, an intermittent top feed dog operating in said opening, a support located below the foot, separate work clamp sections mounted on the support for alternate cooperation with the feed dog and the foot, springs respectively interposed between said sections and the support for pressing said sections upwardly into said cooperative relation with said feed dog and foot, and means located between the support and one of said sections for varying the pressure of the associated spring.

10. In a blind stitch sewing machine, the combination with a horizontal presser foot having an opening, an intermittent top feed dog operating in said opening, a support located below the foot, separate work clamp sections mounted on the support for alternate cooperation with the feed dog and the foot, springs respectively interposed between said sections and the support for pressing said sections upwardly into said cooperative relation with said feed dog and foot, and separate means located between the support and the sections for varying independently the pressures of the associated springs.

11. In a blind stitch sewing machine, the combination with a horizontal presser foot having an opening, an intermittent top feed dog operating in said opening, a support located below the foot, separate bell crank levers fulcrumed on the support to swing about a horizontal axis, each lever including a horizontal arm and a depending vertical arm, work clamp sections respectively pivoted on the horizontal arms for alternate cooperation with the feed dog and the foot, coil springs respectively connecting the vertical arms of the levers and the support for pressing said sections upwardly into said cooperative relation with said feed dog and foot, and a stop screw threadably mounted in the support for engagement by the vertical arm of one lever to variably limit the pressure of the associated spring.

12. In a blind stitch sewing machine, the combination with a horizontal presser foot having an opening, an intermittent top feed dog operating in said opening, a support located below the foot, separate bell crank levers fulcrumed on the support to swing about a horizontal axis, each lever including a horizontal arm and a depending vertical arm, work clamp sections respectively pivoted on the horizontal arms for alternate cooperation with the feed dog and the foot, coil springs respectively connecting the vertical arms of the levers and the support for pressing said sections upwardly into said cooperative relation with said feed dog and foot, and stop screws threadably mounted in the support for engagements by the vertical arms of said levers to variably and independently limit the pressures of the associated springs.

13. In a sewing machine, the combination with a base and a laterally extending arm, of a presser foot mounted on the free end of said arm, a reciprocatory needle supported on the arm above the foot, a work support mounted on the base and having a portion underlying the foot, a foldor support located in front of the work support and mounted on a vertical axis to swing forwardly from an operative position to an inoperative position, and a folder mounted on said folder support for directing a folded fabric to the needle when said support is in its operative position.

14. In a sewing machine, the combination with a base and a laterally extending arm,of a presser foot mounted on the free end of said arm, a reciprocatory needle supported on the arm above the foot, a work support mounted on the base and having a portion underlying the foot, a folder support located in front of the work support and mounted on a vertical axis to swing forwardly from an operative position to an inoperative position, the upper surface of the folder support be ing normally disposed in a lower horizontal plane than the upper surface of the work support, and a folder mounted on said folder support for directing a folded fabric to the needle when said support is in its operative position, said folder support being elevated automatically when swung from its operative position to its inoperative position whereby the folder will clear the work support.

15. In a sewing machine, the combination with a base and a laterally extending arm, of a presser foot mounted on the free end of said arm, a reciprocatory needle supported on the arm above the foot, a work support mounted on the base and having a portion underlying the foot, a post mounted on the base in front of the work support, a bearing collar fixed to the post and provided with a cam, a folder support mounted on said post to swing forwardly from an operative position to an inoperative position, the upper surface of the folder support being normally disposed in a lower horizontal plane than the upper surface of the work support, a folder mounted on said folder support for directing a folded fabric to the needle when said support is in its operative position, and a cam follower fixed to the foldi support in its inoperative position.

er support for cooperation with said cam whereby the folder support will be elevated and the folder will clear the work support when the folder support is swung to its inoperative position.

16. In a sewing machine, the combination with a base and a laterally extending arm, of a presser foot mounted on the free end of said arm, a reciprocatory needle supported on the arm above the foot, a work support mounted on the base and having a portion underlying the foot, a post mounted on the base in front of the work support, a bearing collar fixed to the post and provided with a cam, a folder support mounted on said post to swing forwardly from an operative position to an inoperative position, the upper surface of the folder support being normally disposed in a lower horizontal plane than the upper surface of the work support, a folder mounted on said folder support for directing a folded fabric to the needle when said support is in its operative position, a cam follower fixed to the folder support for cooperation with said cam whereby the folder support will be elevated and the folder will clear the work support when the folder support is swung to its inoperative position, and spring means between the post and the folder support for yieldably retaining the cam follower in engagement with the cam.

1'7. In a sewing machine, the combination with a base and a laterally extending arm, of a presser foot mounted on the free end of said arm, a reciprocatory needle supported on the arm above the foot, a work support mounted on the base and having a portion underlying the foot, a post mounted on the base in front of the work support, a bearing collar fixed to the post and provided with a cam, a folder support mounted on said post to swing forwardly from an operative position to an inoperative position, the upper surface of the folder support being normally disposed in a lower horizontal plane than the upper surface of the work support, a folder mounted on said folder support for directing a folded fabric to the needle when said support is in its operative position, and a cam follower fixed to the folder support for cooperation with said cam whereby the folder support will be elevated and the folder will clear the work support when the folder support is swung to its inoperative position, said collar being provided with a notch for receiving the cam follower to retain the folder CHARLES W. MUELLER.

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