US1989602A - Sewing machine - Google Patents

Description

Jan. 29, 1935. c. w. MUELLER SEWING MACHINE Filed NOV. 18, 1932 6 Sheets-Sheet 1 6. Mae/k7 Jan. 29, 1935. c. w. MUELLER SEWING MACHINE Filed Nov. 18, 1932' '6 sheets sheet 2 gwuc/wfom c. n Mae fler- Jan. 29, 1935. I c, w, MUELLER 1,989,602

- SEWING MACHINE Filed Nov. 18, 1932 6 Sheets-Sheet 3 awuem/bom C. W. Mae/A97" Jan. 29, 1935. c. w. MUELLER SEWING MACHINE Filed Nov. 18, 1932 e Sheets-Sheet 4 C. W. MUELLER SEWING MACHINE Jan. 29, 1935.

, Filed Nov. 18, .1932 s Sheets-Shet 5' I 3mm Gin. Mae/let W Jan. 29, 1935. c. w. MUELLER 1,939,602

' 1 SEWING MACHINE Filed Nov. 18, 1952 6 Sheets-Sheet 6 CM Nae/fier- I Patented Jan. 29, 1935 SEWING MACHINE Charles w. Mueller, St. Louis, Mo., assignor to Lewis Invisible Stitch Machine Company, St. Louis, Mo., a corporation of Maine Application November 18, 1932, Serial No. 643,283

22 Claims.

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

Among the several objects of the invention are to provide a blind stitch sewing machine for use in felling or hemming operations; to provide a stitch forming mechanism for forming a line of lock stitches, and to provide an oscillatory ridge forming means for presenting a ridge of material into needle penetrating position, the ridge forming'means presenting both the base layer and the fell or hem to the needle on certain reciprocations thereof to form resultant anchor stitches and presenting the hem or upper layer only to the needle on intermediate reciprocations thereof to form resultant skip stitches;

to providesuch a machine with a bottom feeding mechanism and a top feeding mechanism, which 2 are arranged in proper cooperative relation whereby the fell or hem will be properly fed; to provide means for oscillating the ridge forming device from the main shaft and to provide means for imparting'the backward and forward travel to the lower feed dog from said ridge forming means, and to provide a supplementary work clamp connected to the vertically reciprocatory main work clamp for cooperation with the stationary presser foot to clamp the body fabric therebetween and thereby firmly retain said body fabric not only against the thrust of the needle but also against the return movement of the lower feed.

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, parts being shown in section, V t

Figure 2 is a left hand elevation thereof,

Figure 3 is a front elevation of the machine, parts being shown in section,

Figure 4 is a detail elevation showing particularly the gear and eccentric driving connections for the ridge'forming disc,

Figure 5 is a detail section showing the connection between the eccentric sleeve driving disc and the associated gear,

Figure 6 is an elevation of said driving disc,

Figure '7 is an elevation showing the ridge forming disc in one extreme position relative to the needle path, together with nections for said disc,

Figure 8 is a similar view but showing the disc in its other extreme position relative to the needle path, I Figure 9 is a top plan view of the presser foot, theridge forming disc, the needle, the lower feed dog, and the upper feed dog,

Figure 10 is a cross sectional view showing more or less diagrammatically the position of 10 the needle, the ridge forming disc, and the material when the needle ispenetrating both the base layer and the hem,

Figure 11 is a similar view but showing the parts when the needle is. penetrating the hem only,

Figure 12 is a perspective view of" the ridge forming disc, the parts being shown in separated relation,

Figure 13 is a top plan view of the main work clamp, the supplemental work clamp, the lower feed dog, and the ridge forming disc,

Figure 14 is a side elevation of the main work clamp showing the supplemental work clamp attached thereto, and

Figure 15 is a perspective viewshowing the main work clamp and the supplemental work clamp in separated relation.

Referring to the accompanying drawings, my improved sewing machine includes a frame comprising a base 5 having a hollow standard 6 rising from the rear right hand corner thereof and having a pair of posts '7, 8 projecting upwardly and located in front of said standard. Extending laterally towards the left from the upper end of the standard is a horizontal arm 9, and extending forwardly from the left hand end thereof to a point in advance of the posts 7, 8 is an arm 10. A stationary presser foot 11 is attached to the front end of the arm 10. A work support or plate 12 is pivoted on the posts '7, 8 through the medium of a bearing rod 13 mounted in said posts and the left hand end of said plate is disposed below the presser foot 11. A spring 14 functions to yieldably urge the work plate upwardly towards the foot, and the upward movement is adjustably limited by a depending arm 15 which is rigid with the table and a cooperating adjustable stop 16 mounted on the base.

Journaled in the horizontal arm 9 is a main rotary shaft 17 which through the usual connections 18 oscillates a needle shaft 19 which is journaled in the forwardly extending arm 10. Fixed to the forward end of the needle rock shaft 19 is a curved needle 20 whichoscillates directly the driving conabove the presser foot and in a path transverse to the longitudinal axis thereof, the forward or work penetrating stroke being from left to right.

Cooperating with the needle 20 to form a series of lock stitches is a rotary hook 21 which is fixed to a shaft 22 journaled in a bearing lug 23 extending forwardly from the front end of the frame arm 10, the hook shaft 22 being disposed in parallelism with the main shaft 17. The hook shaft 22 is rotated from the main shaft 1'7 through the medium of an intermediate or cross shaft 24 which has its forwardend journaled in the bearing lug 23 and its rear end journaled in a bearing 25 on the horizontal arm 9. A 2-to-1 gear coupling 26 connects the main shaft 17 with the rear end of the cross shaft 24 and a 1-to-1 gear coupling 2'7 connects the front end-of the cross shaft 24 with p the hook shaft 22, thus providing a driving connection between the main shaft and the hook shaft which causes the hook to be rotated twice to each revolution of the main shaft.

As previously stated, this machine is particularly adapted for felling operations or for hemming operations, and to this end means are-provided for projecting a ridge of material upwardly through the foot into needle penetrating position during each cycle of operation. The presser foot 11 is formed with 'a longitudinal opening 28 through which-the ridge of material is projected by an oscillatory finger or disc 29. The disc 29 is fixed to a rock shaft 30 journaled in bearings depending from the work support 12, the shaft being disposed in parallelism with the main shaft 17. The rock shaft 30 is oscillated from the main shaft through the medium of the following connections. A driving eccentric 31 is fixed to the main shaft, and surrounding this eccentric is an eccentric sleeve 32 which is positively rotated on the eccentric but at one-half the speed thereof. A disc 33 which is loosely mounted on the main shaft 17 is provided with a radial slot 34 for receiving a slide block 35 fixed to the eccentric sleeve 32 by a shank 36 and a lock screw 3'7 which cooperates with the shank. A driving gear 38 is fixed to the main shaft and rotatable on a stationary shaft 39 mounted in the frame standard 6 is a reduction gear unit including a large gear 40 and a smaller gear 41, the former being in constant mesh with the driving gear 38, and the latter being in constant mesh with a gear 42 fixed to the disc 33. The gear coupling ratio is such that the eccentric sleeve-32 is rotated once during every two revolutions of the main shaft 17. In order to rock the disc supporting shaft 30 from the eccentric 31 and eccentric sleeve 32, I have jou'rnaleda rock shaft 43 insuitable bearings depending from the work support 12 and extending in parallelism with the main shaft 17. A rock arm 44 which is clamped to the rock shaft 43 is connected by-a link 45 to a rock arm 46 clamped to the disc supporting shaft- 30. Also clamped to the rock shaft 43 is an actuating rock arm 47 having a longitudinally extending slot 48. A strap link 49 has one end fitting around the eccentric sleeve 32, and the other end adjustably connected to the arm 4'7 throughthe medium of a clamp screw 50 which passes into the slot 48,

This ridge forming disc 29 is quadrant shaped and includes a ridgeforming concentric surface or portion 51 and a radial rear edge 52 which joins said surface 53. The extent of oscillation of the disc 29 is constant regardless of the fact that both the eccentric 31 and the eccentric sleeve 32 control the movements of the strap link 49. The eccentric 31 functions to oscillate the disc 29 between two fixed radial points, the rear point relative to the needle path being shown by the position of the comer 53 of the disc in Figure '7. The eccentric sleeve 32, which rotates once to every two revolutions of the eccentric 31, functions to vary the position of the angular range of the oscillatory movement of the disc,29, the rear point relative to the needle path being shown by the position of the corner 53 of the disc in Figure 8. It will be noted that in the Figure '7 position, the corner 53 of the disc is in front 'of the needle path whereas in Figure 8'the corner is in rear thereof. It will also be noted that the corner in Figure .8 is higher. relative to the horizontal point of needle penetration than it is in Figure 7 thereby insuring the needle penetrating both the base layer A and the hem or fell B but only the hem in the Figure '7 position, these conditions being clearly disclosed in Figs. 10 and 11.

By reference to the line X-X in Figure 8, it will be noted that the shank 36 is about 25 below the center line and therefore when the eccentric 32 is in this position, the ridge forming disc 29 is in a position to insure the needle penetrating the base layer and the hem as shown in Figure 10. It will also be noted that in Figure '7 the shank 36 has been moved from the Figure 8 position, although the driving eccentric 31 is in the same position as shown in Figure 8, but due to the ratio of the 2-to-1 gearing and to the position of the sleeve eccentric 32, the position of the angular range of movement of the ridge forming disc 29 has been moved to the needle center line-and therefore the base layer will not be lifted a distance sufficient to receive the needle and the latter will enter the fell or hem only as shown in Figure 11. Attached to the ridge forming disc 29 is a finger 54. This finger is U-shaped and includes attaching arms 55, 55 and a nose 56 which projects upwardly from the connecting ends of the arms. These arms are arcuate and are arranged in concentric relation to the disc supporting shaft 30. Clamping screws 5'7, 58 pass through suitable openings in the arms 55 and through openings 59 and 60 in the ridge forming disc 29. The diameter of the opening 60 through which the screw 58 passes has a diameter greater peripheral portions arranged in tandem and of stitches, and in another extreme angular position ofthe disc the low peripheral portion 56 will be presented to the needle and the latter will penetrate the hem only to form resultant "skip stitches. Thus the high and low peripheral portions of the disc cooperate with the needle to periodically vary the depth of the needle penetrationin the work.

It will thus be noted that the ridge formm' g disc 29 is oscillated for a fixed distance and that the position of oscillation of the disc is bodily shifted during successive oscillations thereof.

Cooperating with the bottom of the presser foot 11 is a main work clamp 61 which is rigidly attached to the upper end of a post' 62 which is mounted in the work plate 12 for vertical reciprocations.

A lower 4-motion feed dog 63 operates through feed slots 64, 65 which are formed in the work cations to the work-clamp 61 and also the up and down movements to the feed dog 63, I have J'ournaled a rock shaft 66 in suitable bearings dependingfrom the-work plate .12. This shaft. is rocked from the main shaft 19 through suitable.

connections indicated generally at 67. The rock shaft 66 is provided at one end with a crank arm 68 carrying a crank pin 69 which is engaged by one end of a lift lever 70, the other end of the lever being pivotally connected as at 71 to the lower end of the post 62. The feed dog 63 is pivotally connected to the upper end of a substantially vertically disposed link 72, the lower end of said link being pivotally connected to the lift lever 70. Thus when the feed dog 63 is lifted In order to impart back and forth movements.

into engagement with the stationary foot 11, the work clamp 61 will be lowered, and vice versa.

of commercial hemmer may be either mounted,

on the presser foot or on the work plate as is readily understood by those skilled in the art. It will also be understood that either a single fold'hem or a double fold hem may be employed.

When the work is fed through the machine the hem as well as the base layer immediately under the hem will be formed into a ridge which will be projected upwardly through the opening 28 in the presser foot 11 by the high portion 51 of the ridge forming disc 29. It will be observed that there will be either two or three thicknesses of fabric, depending on the nature of the hem being formed, disposed between the bottom of the presser foot 11 and the top of the main work clamp 61, these thicknesses being located on the right hand side of the disc 29 as viewed in Figures and 11 and on that side of the disc opposite the point of needle penetration. Thus it will be seen that the base layer A is of but a single thiclmess and is located between the bottom of the presser foot and the left hand side of the work clamp and therefore this base layer is not clamped but is free to move. Consequently the ridge formed by the disc 29 will not beheld taut to receive the needle thrust, and neither will said layer be clamped against the foot to resist the dragging action of the feed dog during the return movement thereof. In order to overcome these objections, I have mounted a supplementary workclamp 75 on the main work clamp,

61 and on that side of the main clamp directly under the single thickness or body fabric A. This supplemental clamp 75 is pivotally mounted at its lower end as at 76 on the upper end of an arm 77 which is pivoted as at 78 to the side wall of a recess formed in the left side of the'main work clamp 61. Stop shoulders 79, 80 respectively formed on the main and auxiliary clamps cooperate to limit the pivotal movement of the supplemental clamp relative to the main clamp, and a stop shoulder 81 formed on the main work clamp 61 cooperateswith the upper end of the arm 77 to limit the upward movement thereof. A flat spring 82 is secured to the under side of the main clamp 61 and the free end of this spring extends under the arm 77 and functions to press 'said arm upwardly whereby the supplemental clamp 75 will be yieldingly retained in engagement with the bottom of the presser foot 11. Thus by pivoting thesupplemental work clamp 75 on the arm 77, said clamp will automatically parallel itself with the bottom of the presser foot 11- regardless .of. the vertical position of reciprocation of the'main work clamp 61.

Although, I have disclosed and described a 2-to-1 gear coupling 26 for rotating the hook twice to each revolutionofthe' main shaft, it

will be understood that the ratio of these gears may be changed if desired, and when making such a change it will be only necessary to retime the sleeve 32 in relation to the eccentric 31 as will be readily understood by those skilled in the art.

From the foregoing, it will be readily understood that when a hemming operation is being performed the ridge forming disc 29 will project a ridge of material upwardly through the opening 28 in the presser foot 11 and into needle penetrating position; that in one extremerearward position of the disc 29 the needle will enter and emerge through both the body fabric A and the hem B and form resultant anchor stitches, whereas in thealternate extreme rearward positions of the disc 29, the needle will enter and emerge through the hem B only and form resultant skip stitches; that by means of the finger 54 which is adjustably mounted on the ridge forming disc 29 the machine may be readily adjusted to compensate for different thick-.

nesses of materials; that by connecting the lower feed dog with the rock shaft which oscillates the ridge forming disc, I have eliminated a line of driving connections to the main shaft, and that I have provided a supplementary work clamp for cooperation with the bottom of the presser foot to clamp the base layer against the foot and thereby not only retain said base layer against the needle thrust but also prevent said base layer from being dragged by the feed-dog during the backward movement thereof.

It will be also apparent that the disc 29 and finger 54 cooperate to form peripheral surfaces arranged in tandem and of different radii; that the finger 54 forms a peripheral recess at the forward edge 52 of the disc; that the disc is oscillated in timed relation to the needle reciprocations to successively position the peripheral portion 51 and the peripheral recess in register with the needle path of travel to vary the effective-depth of needle penetration, whereby the needle will penetrate all the layers of the fabric when the peripheral portion 51 of the of the" disc is in register with, the path of needle travel an form a resultant skip stitch; that layer or layers only when the peripheral recess I the action of the main driving connections between the main rotary shaft 17 and the oscillatory disc shaft is modified by the inclusion of the eccentric 32 which is positively rotated by a reduction gear coupling 38, 40, 41, 42 to effect the periodic change in the angular position of the disc; and that the finger 54 which forms the bottom of the peripheral recess, supports the fabric layers against the thrust of the needle when said skip stitches are being formed.

It is of course to be uderstood 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,'an oscillatory ridge-forming disc, means for angularly oscillating said disc for a fixed amount, and means for varying the position of the angular range of movement of said disc during alternate oscillations thereof. a

2. In a blind stitch sewing machine, an oscillatory ridge-forming disc, means for angularly oscillating said disc for a fixed amount, and means for varying the position of the angular range of movement of said disc during alternate oscillations thereof including a driving eccentric, an eccentric sleeve surrounding the eccentric,

and a reduction gear coupling between the eccentric and the sleeve.-

3. In a blind stitch sewing machine, an oscillatory ridge-forming disc, means for angularly oscillating said disc for a fixed amount, and means for varying the position of the angularrange of movement of said disc during alternate oscillations thereof comprising a rock shaft supporting the disc, a main rotary shaft, an eccentric fixed to the mainshaft, an eccentric sleeve surrounding said eccentric, driving connections between the eccentric sleeveand the rock shaft, and a reduction gear coupling between the main shaft and the eccentric sleeve.

4. In a blind stitch sewing machine for felling or hemming, the combination with a stationary presser foot having an opening, of a stitch forming mechanism located above the foot and including a reciprocatory needle having its path of movement across the opening in said foot,

an oscillatory ridge forming disc mounted below.

the foot for projecting a, ridge of hemmed material upwardly through the opening in the foot into needle penetrating position, means for angularly oscillating the disc for a fixed'amount, and means for varying the position of the angular range of movement of the disc during alternate oscillations thereof toinsure the needle pene-" cluding a reciprocatory needle having its path of movement across the opening in said foot,

an oscillatory ridge forming disc mounted below the foot for projecting a ridge of materialupwardly through the opening in the foot into needle penetrating position, means for angularly oscillating the disc for a fixed amount, .and' means for varying theposition of the angular rahge of movement of the disc during alternate oscillations thereof to insure the needle penetrating the hem only during alternate strokes and penetrating both the body fabric and the hem during intermediate strokes, said shifting means comprising a driving eccentric, an eccentric sleeve surrounding the eccentric, and a reduction gear coupling between the eccentric and the sleeve. f

6. In a'blind stitch sewing machine for felling or hemming, the combination with a stationary presser foot having an opening, of a stitch forming mechanism located above the foot and including a reciprocatory needle having its path of movement across the opening in said foot, an oscillatory ridge forming disc mounted below the foot for projecting a ridge of material upwardly through the opening in the foot into needle penetrating position, means for angularly oscillating the disc for a fixed amount, and means for varying the position of the angular range of movement of the disc during alternate oscillations thereof to insure the needle penetrating the hem only during alternate strokes and penetrating both the bodyfabric and the hem during intermediate. strokes, said shifting means comprising a rock shaft supporting the said eccentric, driving connections between the eccentric sleeve and the rock shaft, andareduction gear coupling'between the main shaft and the eccentric sleeve.

'1. In a blind stitch sewing machine, the combination with a frame including a standard, of an arm extending laterally therefrom, an arm extending forwardly from said laterally extending arm, a .depressible work plate disposed in front ofathe'laterally extending arm, a presser foot fixed to the frJnt end of the forwardly extending arm and disposed above one end of the work plate, said foot havingan opening, a main shaft journaled in the overhanging arm, an oscillatory needle shaft journaled in the forwardly extending arm, a curved needle fixed to the forward end of said needle shaft, driving connections between the main shaft and the needle shaft, a rotary hook shaft journaled inthe front end of the forwardly extending arm, a hook fixed to said shaft, driving connections between the main shaft and'the hook shaft, means mounted on the work plate for projecting a ridge of material upwardly through the opening in the foot into needle penetrating position, a vertically reciprocatory work clamp mounted on the work plateand cooperating with the bottom of the foot to clamp the work against the thrust of the needle, and afeed mechanism for intermittently feeding the work past the needle.

. 8. In a blind stitch sewing machine, the combination with a frame including a standard, of an arm extending laterally therefrom, an arm extending forwardly from said laterally extend ing arm, a depressible work plate disposed in front of the laterally extending arm, a presser footfixed to the front end of the forwardly extending arm and disposed aboveone end of the work plate, said foot having an opening, a main shaft journaled in the overhanging arm, an oscillatory needle shaft journaled in the forwardly extending arm, a curved needle fixed to the forward end of said needle shaft, driving connections between the main shaft and the needle shaft, a rotary hook shaft journaled in the front end of the forwardly extending arm, a hook fixed to said shaft, driving connections between the main shaft and the hook shaft \comprising a driving shaft, a 1-to-1 gear coupling between the driving shaft and the hook shaft, and a 2-to-1 gear the opening in the foot into needle penetrating position, a vertically reciprocatory work clamp mounted on the work plate and cooperating with the bottom of the foot to cl'ampthe work against the thrust of the needle, and a feed mechanism for intermittently feeding the work past the needle.

9. In a blind stitch sewing machine for felling or hemming,th e combination with a frame including a standard, of an arm extending laterally therefrom, an arm extending forwardly from said laterally extending arm, a depressible work plate disposed in front of the laterally extending arm, a presser foot fixed to the front end of the forwardly extending arm and disposed above one end of the work plate, said foot having an opening, amain shaft journaled in the overhanging arm, a stitch forming mechanism mounted on the front end of the forwardly extending arm and including a reciprocatory needle having its path of movement across the opening in the presser foot, means for reciprocating the needle from the main shaft, a rock shaft journaled on the depressible work plate and extending under said foot, said rock shaft being disposed in parallelism with the main shaft, an oscillatory disc fixed to said rock shaft for projecting a ridge of material upwardly through the opening in the foot into needle penetrating position, and operating connections between the main shaft and the rock shaft for oscillating the disc for a fixed amount and for varying the position of the angular range of movement of forwardly extending arm and disposed above one end of the work plate, said foot having an opening, a main shaft journaled in the overhanging arm, a stitch forming mechanism mounted on the front' end of the forwardly extending arm and including a reciprocatory needle having its path of movement across the opening in the presser foot, means for reciprocating the needle from the main shaft, a rock shaft journaled on the depressible work plate and extending under said foot, said rock shaft being disposed in parallelism with the main shaft, an oscillatory disc fixed to said rock shaft for projecting a ridge of material upwardly through the opening in the foot into needle penetrating position, and operating connections between the main shaft and the rock shaft for oscillating the disc for a fixed amount and for varying the position of the angular range 'of movement of the disc during alternate oscillations thereof to insure the needle penetrating the hem only during alternate strokes and penetrating both the body fabric and the hem during intermediate strokes, said operating connections comprising an'eccentric fixed to the main shaft,

an eccentric sleeve surrounding said eccentric,

driving connections between the eccentric sleeve and the rock shaft, and a reduction gear coupling 11. In a blind stitch sewing machine, an oscillatory ridge-forming disc having a concentric ridge-engaging edge, and aridge-engaging finger mounted on said disc for fixed adjustments towards and from said edge.

12. In a blind stitch sewing machine, an oscillatory ridge-forming disc having a concentric ridge-engaging edge and a radially extending forward edge merging with'the concentric edge, a ridge-engaging finger pivoted on said disc and provided with a nose located beyond the radial forward edge of the disc, and means for clamping the finger in any position of pivotal adjustment.

13. In a blind stitch sewing machine, the combination with a frame, of a stationary presser foot secured thereto and provided with an opening, a

stitch forming mechanism located above the foot and including a reciprocatory needle having its path of movement across the openingin the foot, a main shaft, an oscillatory shaft disposed below the foot and operated from the main shaft, a disc fixed to the oscillatory shaft for projecting a ridge of material upwardly through the presser foot opening into needle penetrating position, a 4- motion lower feed dog cooperating with the bottom of the foot for intermittently feeding the work past the needle, and means for imparting back and forth movements and up and down movements to the feed dog including'connections between the dog and the disc supporting shaft for imparting back and forth movements to the dog and other connections between the dog and the main shaft for imparting. up and down movements to the dog.

14. In a blind stitch sewing machine for felling or hemming, the combination with a horizontal stationary presser foot having an opening, of a stitch forming mechanism located above the foot and includinga reciprocatory needle having its path of movement across said opening, means for intermittently projecting the base fabric and the superposed hem upwardly through said opening into needle penetrating position, means including a 4-motion feed dog for feeding the work past the needle, a vertically reciprocatory main work clamp for clamping the hem against the bottom of the foot during the return movements of the feed dog and during needle penetrating movements, and an upwardly spring pressed supplemental work clamp mounted on the main work clamp for clamping the body fabric against the bottom of the foot to thereby retain said body fabric against being dragged by the feed dog during its return movement and to retain the fabric stationary against the thrust of the needle.

between the main shaft and the eccentric sleeve.

15. In a blind stitch sewing machine, a staridge formingelement. a 16. In a blind stitch sewing machine, a stationary presser foot, a vertically reciprocatory main work clamp cooperating with the bottom of the foot, an arm pivoted at one end to the main work clamp, a supplemental work clamp pivotedto the free end of said arm for cooperation with the bottom of the foot, and a spring connected to the main clamp and bearing against said arm for pressing the arm and the supplemental clamp upwardly.

17. In a blind stitch sewing machine, a stationary presser foot, a vertically reciprocatory main work clamp cooperating with the bottom of the foot, an arm pivoted at one end to the main work clamp, a supplemental work clamp pivoted to the free end of said arm for cooperation with the bottom of the foot, a spring connected to the main clamp and bearing against said arm for pressing the arm and the supplemental clamp upwardly, and cooperating means between said clamps to limit the pivotal movement of the supplemental clamp.

18. Ina blind stitch sewing machine, a sta-,

tionary presser foot, a vertically reciprocatory main work clamp cooperating with the bottom of the foot, an arm pivoted at one end to the main workclamp, a supplemental work clamp pivoted to the free end of said. arm for cooperation with the bottom of the foot, a spring connected to the main clamp and bearing against said arm for pressing the arm and the supplemental clamp upwardly, and cooperative means between said clamps to limit the pivotal movement of the arm.

19. In a blind stitch sewing machine, an oscillatory ridge-forming disc, means for angularly oscillating said disc, and means for varying the position of the angular range of movement of said disc during successive oscillations thereof.

20. In a blind stitch sewing machine, an oscillatory ridge-forming disc having high and low peripheral portions arranged in tandem,.a reciprocatory needle, means for reciprocating the needle transversely of the disc, and means for oscillating the disc in timed relation to the reciprocations of the needle to thereby present said disc portions periodically to the needle to vary the effective depths of the needle penetrations.

21. In a sewing machine, the combination with a main shaft, of an oscillatory shaft, a ridgeforming disc fixed thereto and having peripheral surfaces of different radii arranged in tandem, a needle reciprocating above the disc, and'driving connections between said shafts for periodically presenting to the needle first one'of said surfaces of the disc and then the other to thereby vary the effective depths of the needle penetrations.

22. In a sewing machine, the combination with a main shaft, of an oscillatory shaft, a ridgeforming disc fixed thereto and having peripheral surfaces of 'difierent radii arranged in tandem, a needle reciprocating above the disc, and driving connections between said shafts for periodically presenting to the needle first one of said surfaces of the disc and then the other to thereby vary the effective depths of the needle penetrations, said driving connections including a reduction gear and an eccentric driven thereby.

CHARLES W. MUELLER.

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