US1711483A

US1711483A - Thread-controlling mechanism for buttonhole-sewing machines

Info

Publication number: US1711483A
Application number: US167622A
Authority: US
Inventors: Edward B Allen; Benjamin F Crosby
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1927-02-12
Filing date: 1927-02-12
Publication date: 1929-05-07
Anticipated expiration: 1946-05-07
Also published as: FR640553A; DE479945C; GB290476A

Description

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THREAD CONTROLLING MECHANISM FOR BUTTONHOLE SEWING MACHINES 1927 7 sheets-sheet 2 Filed Feb. l2

May 7, 1929. E. B. ALLEN ET AL THREAD CONTROLLING MECHANISM FOR BUTTCNHOLE SEWING MACHINES Filed Feb.-12, 1927 '7 Sheets-Sheet 5 @4 om A?. /W

Www/eme; 1

May 7, 1929. E. B. ALLEN ET AL 1,711,483

l THREAD CONTROLLING MECHANISM FOR BUTTONHOLE SEWING MACHINES A Filed Feb. 12, 192'?- 7 SheeS-Sheekl 4 May 7, 1929- E. B. ALLEN ET AL 4'I'IRED CONTRLLING MECHANISM FOR BUTTONHOLE SEWING' MACHINES '7 Sheets-Sheet 5 mw MN @N Q Kak E NJ my w d N m Q N K May 7, 1929.` E. B. ALLEN ET AL 1,711,483

` THREAD CONTROLLING MECHANISM FOR VBUTTONHOLE SEWING MACHINES Filed Feb. 12, 1927 7 SheetS-Sheet 6 J Y JM y HMHMHMMHHHHMHIHHHMJHMHH 132 IZ] Z/Z 113 Ilz- May 71.1929- E. B. ALLEN ET AL 1,711,483

THREAD CONTROLLING MECHANISM FOR BUTTONHOLE SEWING MACHINES Filed Feb. 12, 1927 '7 sheetssheet 7 HII IIIIIIHHI IIIIIIIIIIIII llllllllllHllllHllHl CII Patented May 7, 1.929.

' UNITED STATES 1,711,483 PATENT OFFICE.

EDWARD B. ALLEN, OF`NEWTOWN, AND BENJAMIN F. CROSBY, OF STRATFORD, CON- NECTICUT, ASSIGNORS T THE SINGER MANUFACTURING COMPANY, OF ELIZA- BETH, NEW JERSEY, A CORPORATION OF NEW JERSEY.

THREAD-CONTROLLING MECHANISM FOR BUTTONHOLE-SEWING MACHINES.

Application led .February 12, 1927. Serial No. 167,622.

Thisl invention relates to sewing machines and more particularly to machines of the buttonhole sewing type with mechanism for severing and controlling. the threads and cordbetween buttonhole stitching cycles.

An object of the present improvement is to sever the upper and lower threads and cord below thewo'rk and eliminate all impedimenta from the clamp-plates and upper clamping feet so that the work-clamp itself may be made in simple form avoiding obstruction of the operators view of the work in locating the Work relative to the workclamp preparatory to starting the machine.

Further objects of the invention are to 'provide the necessary thread-handling aecessories to avoid skipped stitches at the bcginning of the sewing operation and insure that the sewing operation is properly started.

The objects of the invention are attained in an automatic buttonhole sewing machine which requires the operator merely to place th'e work in the open work-clamp andpress the starting button; the machine operating automatically to close the work-clamp, cut and stitch the buttonhole, sever all threads and cord below the work close to the last stitch, and open the work-clamp so that the work may be removed from the machine with the buttonhole entirely finished and requiring no subsequent retrimming of. the ends of the sewing threads or cord.

To the attainment of the cndsin view there is provided in combination with means below the work-clamp forsevcring all threads and cord close to the last stitch, a pull-off device operating on the needle-thread between the needle andthe work independently of the work-clamp and while the work is held clamped and under control, to provide a needle thread-end of measured and suflicient length below the needle-eye to insure proper starting of the next sowing operation, Without unthreading the needle or skipping stitches, and without the necessity of providing mechanism for gripping'the beginning end ot' the sewing thread-while the'initial stitches are being sewn, or for trimming the beginning thread-end or ends.

To make it easier in some cases for this pull-01T to draw needle-thread downwardly through the needle-eye there may be combined with it' a needle-thread slaekener operating at the close of thestitching cycle between the tension device and the supply spool to pull slack-thread from the spool and thus avoid an undue drag on the thread as it is being pulled through the needle-eye. A needle-thread tension release is also preferably provided.

In some cases it may also be desirable to provide a needle-thread pull-back device between the tension device and the needle to temporarily shorten the needle-thread-end sufficiently to avoid accidental clamping of such thread-end by the upper clamping feet when the work-clamp is closed.` It is to be understood, however, that this pull-back de- ,vice is not essential and is provided only in cases where the needle-thread-end may possibly be caught by the work-clamp.

s Means are also preferably provided for releasing the under-thread-tension vbetween sewing periods and prior to the thread and cord-severing operation, so that the under thread will be free from strain when it is cut, whereby recoil of the under thread due to its elasticity and consequent possible unthreading of theunder needle is avoided.

In the accompanying drawings Fig. l is a right side elevation ot' a buttonhole sewing machine embodyingthe invention. Fig. 2 is a left side elevation of the machine. Fig. 3 is a detail view of the tension releasing mechanism shown in Fig. 2. Fig.'4- is a front endelevation of the lower part of the machine. Fig. 5 is a bott-om plan View of the machine. Fig. 6 is a section on the line 6-6, Fig. 5. Fig. 7 is a4 reverse side View of the parts'shown in Fig. 6. Fig. 8 is a section on the line 88, Fig. 6. Fig. 9 is a top plan view of the turret and thread-cutting mechanism in thread-cutting position. Fig. 10 -is a top plan view of the rear left corner of the travelling work-clamp. Fig. 1-1 is a bottom plan View of a portion of the travelling work-clamp. Fig. 12 is a front side elevation of the needle-thread pull-0H and thread-cutter in the positions they occupy during a sewing operation. Fig. 13 is a similar View at theend of a sewing operation showing the movement of the pull-off to seize the needle-thread. Fig. 14 isa similar View showing how the needle-thread .is pulled olli' by the return movement of the pull-ofi' member before the thread-cutter advances from full to dotted line position. Fig. is a reverse side view of the parts shown in Fig. 14. Figs. 16 and 17 are detail views of the pull-olf member and Fig. 18 is a bottom plan view of the pull-off and its actuating member. y

In the preferred embodiment of the invention, as illustrated, 1 represents the hollow bed of a buttonhole sewing machine from which bed rises the standard 2 of the overhanging bracket-arm 3 terminating in the head 4. l

The stitch-forming mechanism is of the well known type embodying an upper straight depth-stitch needle 5 and a lower curved slit-stitch needle 6, the former being carried by the rec-iprocatory needle-bar 7 and the latter by the usual turret 8 to which needle-bar and turret the usual turning movements are imparted by the connected upper and lower sector gears 9, 1() which are actua-ted in unison by the usual connections Vwith the cam-groove 11, Fig. 5, in the feedwheel 12. This well known mechanism is shown, for example, in the Allen Patents No. 1,162,207, Nov. 30, 1915; No. 15,324, reissued Apr. 4,1922, and No. 1,534,017 lApr. 21,

1925. The mechanism operates to rotate the stitch-forming devices in one direction dur-l ing the sewing at one or both ends of the buttonhole and to reversely rotate the stitchforming devices between sewing periods to restore them to initial position. The stitchforming mechanism is actuated from the main sewing shaft 13 which also drives the feed-wheel 12 in step-by-step fashion, during the sewing, through the well known pin Y and-star wheel drive 14, Fig. 5, and the usual train of gears 15, such as shown 1n said i Alren reissued patent No. 15,324.

he work-clamp is of the travelling type, that is, it is first rapidly moved over the bed 1 to carry the work forwardly from buttonhole cutting position to stitching position, then more slowly moved in step-by-step fashion to place the stitches about the buttonholc, and then rapidly returned to buttonhole cutting position. It is constructed substantially in accordance with the disclosure of said Allen reissued patent and comprises the lower clamp-plates 16 and upper clamping feet 17 which arc depressed into clamping engagement with the work by a rocking movement of t-he connected rock-shaft sections 18 to one of which is connected an arm 19, Fig. 1, adapted to be depressed by the usual clamp-closing lever 20 actuated at the beginning of a buttonhole making cycle by a cam-groove 21 in a continuously running pulley 22 coaxial with the buttonhole cuttershaft 23. A slide-pin 24 carried by the rearwaildly extending arm 25 of the clamp-closing lever 2() is permitted to enter the camgroove 21 for one revolution of the pulley 22 whereupon it is ejected and latched in ejected position as explained in said Allen reissued patent.

The clamp-plates 16 are carriedv by the cross slide-plate 26 which, in turn', is carried by the longitudinal slide-frame 27 to which travelling movements are imparted by means of the link connection 28 with the longitudinal feed-lever 29 having a follower 30 working in the longitudinal feed-cam-groove 31 in the feed-wheel 12. As the present machine is designed to sew a straight as distinguished from an eyelet-end buttonhole, there is no need for moving the cross slideplate 26 relatively to the longitudinal slide frame 27 and hence Such plate and frame are held relatively stationary at all times.

The rapid feed of the 'work-clamp from buttonhole-cutting to stitching position and return is'eft'ected by the usual constantly running rapid feed driveshaft 32, Fig. 5, Which through a worm and gear reduction 33 drives the live element 34 of a clutch,tl1e driven element 35 of which is fast on the cross-shaft 36 which 'is connected by the bevel gear 37 to drive in one-to-one relation the feed-Wheel 12. It will be understood by referring to said Allen reissued patent that the withdrawal of the cone 38 from the driven clutch element 35 effects engagement of the driving and driven clutch elements, while projection of the cone l38 toward the driven clutch element 35 effects the declutching of the parts 35 and 34. The cone 38 is actuated by the usual clutch operating arm 39 on the endwise slidable rod 40 carrying the lateral pin 41 and downwardly extending arm42, Fig. 6.

As disclosed in the Allen Patent No. 1,548,- 815, Aug. 11, 1925, there is mounted in the base 1 on the bracket 43, Fig. 5, a continuously rocking bellcrank-lever 44, 45, Fig. .6, the forked arm 45 of which embraces the crank 46 on the rapid-feed or power-shaft 32. Pivoted on the arm 44 is a single reciprocating bar 47 the free end of which has connected to it a lspring 48 which pulls the bar 47 upwardly against the seat 49 of the latch 50 pivoted at 51 on the bed 1. The bar 47 reciprocates idly when held down by the latch 50. When the latch 50 is withdrawn to release the bar 47, the latter is drawn upwardly by its spring 48 and the shoulder 52 engages the pin 41 and pushes the slide-bar 40 to the right, Fig. 6, to withdraw the cone 38 from the clutch-elements 34, 35 and effect the coupling of the rapid feed or power-shaft 32 to the cross-shaft 36 to drive the feed-wheel 12 at its rapid rate. When the rod 40 is pushed to clutch-engaging position it is held there by engagement of the shoulder 53 onthe lever 54 with the lower end of the arm 42 on the rod 40. The arm 54 is pivoted on the screw 55 .coaxial with the pivot-screw 56 for the bellcrank-lever 44,45. and has connected to it one end of a spring 57 the other end of which is anchored at 58 to the hub of the arm 39. Thus the lever 54 and shoulder 53 act as a spring latch to hold the slide-rod 4() in clutch l-SO engaging position. During the return movement of the bar 47 the inclined shoulder 59,

' Fig. 6, engages the pin 41 and causes the bar 47 to be depressed suiiiciently to be reengaged in idling position by the latch 50.

The cross-shaft 36 has tiXed to it the usual removable pattern-wheel which through the lever 61 and link 62 operates the startand stop-motion devices to control the period of action of the stitch-forming mechanism. The pattern -wheel 60 also carries the tripping points 63 which tilt the lever 64 and control the throwing out of the rapid drive for the feed-wheel 12. rlhe lever 64 is forked at its rearward end Fig. 2 to embrace the end 65 of the latch-lever 54. Hence when the lever 64 is tilted by one of the tripping points 63 the latch-lever 54 is depressed and the arm 42 and slide-rod 40 released whereupon the spring 66, Fig. 5, acts immediately to slide the rod 40 to its ,rapid-feed-cluteh disengaging position. The present rapid-feed-clutch disengaging mechanism acts more quickly than that disclosed in the Allen Patent No. 1,548,815, and insures a high degree of accuracy in the finished product of the machine. The controlling mechanism for initiating the rapid feed. prior and subsequent to sewing is subst-ant-ially the same as that disclosed in said Allen Patent No. 1,548,815, and comprises the rockshaft 67 having an arm 68, Fig. 2, engaging the latch 50, another arm 69 adapted to be depressed by a cam point`70 on the cutter-shaft clutch-disk 71, and a third arm 72 adapted to be elevated by the lever 73 actuated by the stop-motion device S.

The present machine is of the cut lirst I type, that is, it cuts the buttonhole before stitching it. The buttonhole cutting mechanism is constructed substantially in accordance with the disclosure of said Allen Patent No. 1,548,815, and embodies the travelling buttonhole cutter-levers 74, 75, which are given their customary travelling and closing l and opening movements byl suitable cams on the cutter-shaft 23' to which a single rotation is imparted prior to stitching by the continuously rotating pulley 22 acting through a onerevolution clutch. A cam 76 on the cuttershaft 23 acts upon the T-shaped lever 77 after the buttonhole is cut to project the nose 7 8' of said lever into operative engagement with the usual clamp-spreading mec ianism 79. The work-clamp is opened and unspread by action of a tooth 80 on the pattern-wheel 60 which lifts the follower-roll 81 on the lever 82 fulcrumed at 83 on the bed 41. The lever 82 is connected by the link 82 to-the lever 84 fulcrumed at 85 on the bracket-arm standard 2. When the lever 84 is rocked by the lever 82 it pushes the front end of the rod 85 fulcrumed to it at 86 against the usual clampopening arm 87. The rod 85 carries the usual depending arm 88 which strikes the clamp-unspreading lever 89, the parts 85, 88

and 89 being substantially the saine as disclosed in said Allen reissued patent.

The machine is provided with mechanism for cutting all threads and cord below the work close to the last stitch; such mechanism being preferably constructed substantially in accordance with the disclosure of' the Allen Patent No. 1,600,206, of Sept. 21, 1926, and including a scissors thread and cord-cutter 91, Fig. 4, carried by the lever 92 fulcrumed at 93 and actuated by the link connection 94 with the lever 95, which is fulcrumcd at 96, Fig. 1, and actuated by the cam-groove 97 in the gear-wheel 87. The cam-groeve 97 Yhas a hump 98 at one point in its cycle which is timed to advance and retract the scissors 91 after the sewing ot' the buttonhole has been completed and the workclamp returned to buttonhole cutting position, but before the work-clamp has been opened. The scissors 91 carry a

waste needleloop gripper

99, 100, similar in function to that disclosed in the Allen Patent N o. 1,579,200, of April diti'crent manner. 1n the present instance the gripper-jaw 100 has an inclined outer edge 101- which engages the post 102 on the turret 8 when the scissors 91 are advanced to threadcutting position. When the scissors 91 and

gripper

99, 100, are retracted, the incline 103, Fig. 9, on the tail of the jaw 100 engages the stationary bracket 104, Figs. 2 and 4, and opens the gripper to release the waste needle-thread loop. The tail of the jaw 100 carries a leaf-spring 105, Fig. 9, which presses frictionally upon the tail Aet' the jaw 99; the spring 105 having a transverse rib 106 which engages over the opposite edges 107 of the tail of the jalw 99 to hold the jaw 100 in definite open arid elo'scd p0- sit'ions. The movable scissors blade is actuated by the pin 108 which it carries andwhich works in the cani-groove 109 in the stationary )late 110.

The present machine, unlike those disclosed in the Allen Patents Nos.f1,579,200 and 1,600,206, hasv no means yon the` upper workclaniping feet for severing and 'holding the needle-thread. To insure that the end of needle-thread hanging from the needle atv the beginning of a sewing operation will be long enough to insure the proper formation of the initial stitches wit-hout being held, a novel form of needle-thread pull-off is provided.l This pull-ofil is constructed and mounted entirely independently of the work-clamp and operates to pull a measured amount of needlethread through the eye of the needle, before the work is released by the work-clamp and is thus under control, and before the threads and cord are severed below the Work.

The pull-off is preferably in the form ofa bellcrank-

lever

111, 111 fulcrumed at 112 on the bracket 113, Fig. 2, iixed to the stationary fulcrum-pin 114 for the sector-gear 6, 1926, but actuated in a 9; the fulcrum-pin 114 being carried by the overhanging bracket-arm 3. The arm 111 is preferably formed at its lower end with a thread-engaging hook 115 the beak 115 of which is bent forwardly so as to stand at an angle to the plane of action of the hook proper.

The arm 111 of the pull-off has pivoted thereto at 117 a short upstanding arm 118, to which is connected one end of a spring 119 anchored at its opposite end to the arm 111. The spring 119 yieldingly holds the arm 118 against the stop-pin v120. The arm 118 stands in the path of movement of the cam-block 121 on the under side of the sector-gear 9. The cam-block 121 has an inclined surface 122 followed' by an abrupt shoulder 123. During the oscillation of the sector-gear 9 in one direction, Fig. 12, the Cain-block 122 merely tilts the arm-118 away from the stop-pin 120, at the same time stretching the spring 119. After the camblock 122 passes the arm 118 the spring 119 restores the arm ,118 to its upstanding position as shown in full lines, Fig. 13. During the oscillation of the sector-gear 9 in the reverse direction, the inclined face 122 of-thc cam-block 121 depresses the

arm

118 and 111 thereby shifting the pull-off arm 111 to dotted line position, Fig. 13, across the lead of the needle-thread t which at this time extends downwardly and rearwardly from the needle-eye to the last stitch, Fig. 17, the work having been carried rearwardly by the rapid feed of the work-clamp from stitching to buttonhole cutting position. As soon as the abrupt shoulder 123 passes 'the arm 118 the coil-spring 124 around the fulcrum 112 of the pull-off lever 111, 111', quickly moves the pull-oft' lever from dotted line position, Fi 13, to full line position, Fig. 14, during wich movement the hook 115 seizes the needle-thread t and pulls a measured amount through the eye of the needle. Subsequently the scissors 91 are advanced to dotted line position,-Fig. 14, to sever the upper and under threads and cord, after which the work-clamp is opened to release the work.

To avoid straining the needle and thread, it is preferred to provide means for releasing the usual needle-thread tension device and means on the supply side of the tension device. for slackening the needle-thread from the supply spool. The thread-slackener comprises a bellcrank-lever 125, the short arm of which is connected by a link 126 to the upper end of a lever 127 fulcrumed at 128 on" the bracket-arm 3. Fulcrumed at 129 on the lower end of the lever 127 is a depending arm 130 which is normally held in engagement with the stop-pin 131 by the spring 132. Mounted on the longitudinal slide frame 27 of the work-clamp is an actuator block 133 readily passing under the arm 130 on the forward movement of the work-clamp. The block 133 is so positioned, however, that its rear end engages the arm 13() on the rearward motion of the workclamp in sewing the final stitches and pushes the lower endvof the lever 127 rearwardly thereby moving the long or threaded arm of the bellerank-lever125 downwardly to dotted line position, Fig. 2, after which the block 133 passes and releases the arm 130 early in the rapid feed of the Work-clamp to initial or buttonhole-cutting position, whereupon the spring 134 anchored at one end to the lever 127 and at its opposite end 135 to the machine frame, restores the thread-slackener 125 to initial or full line position. Slack thread is thus provided immediately adjacent the tension device 136 at the close of the sewing operation. i The release of the tension device 136 is effected during the rapid shift of work-clamp from' sewing to buttonhole cutting position. Secured to the rear left-hand corner of the longitudinal slide frame 27 of the workclamp is a longitudinally adjustable plaie 137 having its outer rear corner beveled or inclined at 138.y Rearward motion of the work-clamp from dotted to full line position, Fig. A10 carries the incline 138 against the lower end of the tension release lever 139 and pushes such end outwardly. The lever 139 is fulcrumcd between its ends at 140 on the bracket 141 fixed to the bracket-arm 3, hence outward motion of the lower end of such lever causes the adjustable button 142 mounted at its upper .end to ybe pushed against the usual release-pin 143 of the tension device 136. The spring 144 yieldingly urges the lever 139 to tension restoring position which action takes place when the workclamp is rapidly moved from buttonhole cutting to sewing position at the beginning of a buttonhole making cycle.

In the particular embodiment of the invention herein shown and described it is ldeemed preferable to pull back through the needle-eye a measured amount of needlethread so that the needle-thread end will not be in danger of being caught under the workclamping feet when lthe latter are closed. To this end there is pivotally secured to the forward end of the clamp-closing lever 20 a two sectioned bar 145 of adjustable length working in a guide 146 secured to the bracketarm 3. The two sectionsv of the bar 145 are held together by the clamp 147. The upper end of the bar 145 has a lateral extension 148 overhanging the needle-thread leading from the stationary guide-post 149 to the upper end of the hollow needle-bar 7. When the clamp-closing lever 20 is actuated it pulls downwardly upon the bar 145 and causes its upper end 148 to engage the needle-thread and shorten the end below the' needle-eye.

lTo insure retention of the needle-thread in the hook 115 so that the shortened threadend will be held tov one side and out of range of the work-clamping feet, a light leafspring 151 is secured by the screw 152, Fig. 1T, to the pull-off lever 111. This spring 151 bears lightly upon the thread in the hook 115 and retains the'thread-end in the hook while it is being shortened. The spring 151 is purposely made too weakto hold the thread-end after the stitch-forming mechanism is started, the thread-end 'being drawn out of the hook duringl the iirst descent of the needle but after'the slack provided by the pull-back device` has been recovered below the needle-eye due to the descent of the needle; the length oli the thread-end being such that it is drawn or absorbed into the initial stitches.

The under thread tension device 152, Figs. 1 and 4, is of common lform including a pair of spring-pressed disks between which the under thread runs on its way to the under needle 6. During the sewing, these disks eX- ert a tension on the under thread. After the sewing completed, however, and the rapid shift of the work-clamp to buttonhole cutting position is taking place, the inclined edge' 153, Fig. 11, of the cam-plate 154, screwed to the under side of the cross slideplate 26 in moving from dotted line position to full line position, engages the tail 155 of the tension release lever 156 and shifts it from dotted to full line position, Fig. 11, thereby projecting the lower end 157 of .the lever 156 between the disks of the tension device 152, Fig. 1, and releasing the tenslonon the under thread prior to the thread and cord severing operation.

Having thus set forth the nature of the invention, what we claim herein is l. In a machine of the buttonhole type, the combination with stitch-forming mechanism including a reciprocating needle, a workclamp, clamp-opening mechanism and means below the work for severing the needle-thread,

of means above the work acting prior to the' opening of the work-clamp to pull suflicient needle-thread downwardly through the eye o f the needle to provide for the formation of the initial stitches of the next biittonhole.

2. In a machine of the buttonhole type, the combination with stitch-forming mechanism, a work-holder, a means for relatively moving them into and outl of stitching relation, of means for severing the needle-thread below the work, and means timed to act after the stitch-forn'iing mechanism and work-holder have been relatively moved out of sewing relation, and before the needle-thread is severed, to pull needle-thread downwardlythrough the eye of the needle.

3. In a sewing machine, in combination, a frame formed with a bed and overhanging bracket-arm, stitch-forming mechanism including a reciprocating needle journaled in the bracket-arm, means below the work for severing the needle-thread, and a pull-oftl lever carried by the bracket-arm and timed to pull needle-thread downwardly through the eye of the needle before the needle-thread is severed.

4. In a sewing machine of the buttonhole type, the combination with stitch-forming mechanism including a reciprocating needle, a work-clamp, and means below the work for severing the needle-thread, of a pull-oil' device mounted above the work independently of the work-clamp in position to engage the needle-thread between the needle and the work, and means for causing said device to engage the needle-thread and pull it downwardly through the needle-eye before the thread is severed.

5. In a sewing machine of the .buttonhole type, the combination with stitch-.forming mechanism, means for rotating the stitchforming mechanism duringthe sewing and for reversely rotating the stitch-forming mechanism between sewing periods, a. work-clamp, means below the work for severing the needle-` thread, and a needle-thread pull-off supported above the work independently of the workelamp and arranged to be actuated by the stitch-forming mechanism rotating means. i

6. The combination with stitch-forming lnechansm including a. reciprocating needle, and means below the work for severing the needle-thread, of pull-off means above the work for pulling needle-thread downwardly through the needle-eye, a needle-thread tension device, a second pull-off means on the supply side of the tension device for providing slack needle-thread, and means for releasing the tension device prior to the action of said first-mentioned pull-off means.

7 In a machine of the buttonhole type, the combination with stitch-forming mechanism including a reciprocating needle, a workclamp, clamp-closing mechanism, means be low the work for severing the needle-thread, means above the work for pulling off needlevthreadloetween the needle and the work before it is severed, and means for pulling back a measured amount of needle-thread to shorten the needle-thread end so that itwill'not be caught by the work-clamp when the latter is closed at the beginning of` the neXt buttonhole making cycle.

8. In a machine of the buttonhole type, the combination with stitch-forming mechanism including a reciprocating needle, a workelamp, clamp-closing mechanism, -means below the work for severing the needle-thread, means above the work for pulling olf needlethread between the needle and the work before it is severed, and a needle-thread pull-back actuated by the clamp-closing mechanism.

9. In a sewing machine of the buttonhole type, the combination with stitch-forming mechanism, a travelling work-clamp, a needlethread tension device, and means for severing `the needle-thread, of a needle-thread slackv ener on the supply side of the tension device,

and means actuated by the travelling Workclamp for operating said needle-thread slackener.

l0. In a sewing machine of the buttonhole type, the combination with a reciprocating' needle, a work-clamp, a needle-thread tension' device, and means for severing the needletype, in combination, stitch-forming mechabove the work independently of the worki clamp and having a fixed path of movement adjacent thc needle, whereby the lead of the needle-thread between the needle and the work will be carried within the range of action of the pull-off when the work-clamp is returned from stitching to buttonhole cutting position.

In testimony whereof, we have signed our names to this specilication.

EDWARD B. ALLEN. BENJAMIN F. CROSBY.