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19

7) Adjusting the thread tension

The result of the needlework depends on the sewing conditions such as the sewing material, used thread and stitch length.

So please adjust as desired.

good sewing

upper thread tension is strong while the lower thread
tension is weak.

upper thread tension is weak while the lower thread
tension is weak.

(1) Adjusting the upper thread tension

Like in figure 26, turning the tension adjustment nut of

the thread tension control assembly clockwise makes the

upper thread tension stronger and counterclockwise

makes it weaker.

[Figure 26]

strong

strong

weak

weak

(2) Adjusting the lower thread tension

Like in figure 27, turning the tension adjustment nut

①

of the hook clockwise makes the lower thread tension

stronger and counterclockwise makes it weaker.

weak

strong

[Figure 27]

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Summary of Contents for KM-757

Page 1: ...2 Keep this manual in a safe place for future reference in case the machine breaks down User s Manual KM 757 High speed two needle drop feed needle feed sewing machine with automatic thread trimmer KM 797 High speed two needle drop feed needle feed sewing machine with automatic thread trimmer for each needle M MM ME E 0 05 50 06 62 29 9 ...

Page 2: ...s to satisfy increasingly growing and sophisticated needs of the sewing industry by offering diverse functionalities excellent performance remarkable power enhanced durability and refined design Read all instructions in this manual thoroughly before proceeding with operation of the sewing machine to achieve maximum performance Note that specifications of this product may be changed at any time wit...

Page 3: ...dle 16 2 Removing bobbin and bobbin case 16 3 Winding the lower thread 17 4 Routing the lower thread 17 5 Inserting the bobbin 18 6 Routing the upper thread 18 7 Adjusting the thread tension 19 8 Adjusting the height and pressure of the presser foot 21 9 Adjusting the needle and feed dog timing 21 10 Adjusting the height of the feed dog 22 11 Adjusting the needle and hook timing 22 12 Clearance ad...

Page 4: ...shall be observed strictly Otherwise the user will be killed or suffer severe physical injuries Instructions here must be observed or the user could suffer fatal or severe physical injuries Instructions here should be observed or the user could face physical injuries or mechanical damages Danger The meaning of symbols This symbol means a must not This symbol means a must for safety This symbol mea...

Page 5: ...y to occur according to the environment in which the machine is being installed Therefore the following preconditions should be fulfilled ⓐ Please keep the order from top to bottom when unpacking the package Especially mind that the nail on the boxes ⓑ Because machines are apt to be contaminated and corroded by dust and moisture you should install the climate controller and should clean the machin...

Page 6: ...n threading the needle or before checking after sewing be sure to stop the machine ⓗ Don t switch on the power supply with the foot on the pedal ⓘ Don t run the machine when the cooling fan are not running Be sure to clean the air filter in the control box once a week ⓙ If possible keep off from the strong electronic wave like a high frequency welding machine 1 4 Machine Operation Warning Warning ...

Page 7: ...Be sure to wait at least 360 seconds before opening this cover after turn off main switch and unplug a power cord 고압 전류에 의해 감전될 수 있으므로 커버를 열 때는 전원을 내리고 전원 플러그를 뽑고 나서 360초간 기다린 후 여십시오 CAUTION 경 고 Do not operate without finger guard and safety devices Before threading changing bobbin and needle cleaning etc switch off main switch 손가락 보호대와 안전장치 없이 작동하지 마십시오 실 보빈 바늘교환시나 청소전에는 반드시 주전원의 스위치를 꺼 주십시오 CAUT...

Page 8: ...dle drop feed needle feed standard hook sewing machine High speed two needle drop feed needle feed standard hook sewing machine with automatic thread trimmer Servo motor High speed two needle drop feed needle feed standard hook sewing machine with automatic thread trimmer 470 motor High speed two needle drop feed needle feed double hook sewing machine High speed two needle drop feed needle feed do...

Page 9: ...ickness sensing type SPF 4 A solenoid operating structure where the presser foot gets lifted automatically with pedal reverse gear stage 1 operation 3 470 motor MODEL PM470 PHASE 1 1 1 1 3 3 3 3 1 1 3 3 HERTZ 5 50Hz 6 60Hz 5 50Hz 6 60Hz 5 50Hz 6 60Hz 5 50Hz 6 60Hz 5 50Hz 6 60Hz VOLT 1 110V 2 220V 3 380V 4 110V 220V 5 220V 380V PM470 4 470 motor controller MODEL PC470 VOLT 1 110V 2 220V B 001 2 Ser...

Page 10: ... sewing machine can be adjusted after unfastening the fixing nut and then turning the middle linking bar clockwise to raise and counterclockwise to lower After finishing the adjustment tightly fasten the fixing nut 4 According to the installation position of knee lifting solenoid the operation noise operation load and presser foot elevation range may differ Please assemble so that the machine will...

Page 11: ...oil refills Caution Plug in only after oil supply is finished If the operator mistakenly steps on the pedal with the plug in the machine will start automatically and can cause severe injuries When handling lubricants wear protective glasses or gloves to avoid contact with your eyes or skin Inflammation may be caused otherwise Never drink lubricants since they can cause vomiting or diarrhea Keep ou...

Page 12: ...aching the belt cover A to the machine body assemble in advance the rubber collar and washer and fixing nail on the to be attached side of the cover as can be seen in picture K of Figure 8 2 Attach belt cover A onto the machine body as can be seen on Figure 8 Now if a bobbin winder is attached on the table lay down the machine body on its back and attach the belt cover A Figure 6 Figure 7 Figure 8...

Page 13: ...ing on the 470 motor external location detector After assembling the parts in the numbered order as in Figure 12 adjust the synchronization shaft horizontally such that the photo film is placed at the center of the photo interrupter as in Figure 13 Then fasten it tightly with two fixing screws using a hexagonal wrench Caution As can be seen on figure 12 make sure that the marks DOWN and UP face th...

Page 14: ...the pulley are aligned when the needle is in an up position If not adjustment to the photo film of the location detector or to the location of the magnetic holder will be necessary since there may be problems with the trimming In other words the needle s up stop position should be identical with the stop position of the needle bar after the trimming operation which would signify that there is noth...

Page 15: ...eginning When the machine is in a stop mode you can change the up down position of the needle bar by pressing the reverse button Lightly pressing the button once when the needle is in a down stop position will stop the needle bar in a high position Pressing the reverse button twice within less than a second when it is in an up stop position will stop the needle bar in a low position In short the b...

Page 16: ...f the operator mistakenly steps on the pedal while the power is on the machine will start automatically and can result in physical injuries When using clutch motor be aware that the motor will continue to rotate for a while even after the power is switched off due to inertia Start to work on the sewing machine only after the motor has come to a complete stop Caution Turn off the power when adjusti...

Page 17: ... Applicable models KM 797 KM 797BL KM 797 7S KM 797 7N Applicable models KM 797BL 7S KM 797BL 7N 3 Winding the lower thread 1 Winding the lower thread A Push the thread through the hole and wind it from the back to the front of the tension adjusting plate B Bring the thread toward the bobbin and wind the thread around the bobbin about 5 6 times in the clockwise direction C Push the lever so that t...

Page 18: ...ere the thread is rolled onto or the bobbin case into the hook After laying down the bobbin holder close the slide plates on the right and left Caution Turn off the power switch when routing the upper thread If the operator mistakenly presses down on the pedal while switched on the machine will start automatically and can cause physical injuries When using the clutch motor be aware that the motor ...

Page 19: ...ile the lower thread tension is weak 1 Adjusting the upper thread tension Like in figure 26 turning the tension adjustment nut of the thread tension control assembly clockwise makes the upper thread tension stronger and counterclockwise makes it weaker Figure 26 strong strong weak weak 2 Adjusting the lower thread tension Like in figure 27 turning the tension adjustment nut of the hook clockwise m...

Page 20: ...adjustment of plate opening level put the solenoid in action and adjust by moving solenoid collar back and forth to make the opening of the thread tension adjusting plate 0 8 mm Also when the thread release solenoid is not in action check whether the plates are closely adhered to each other See Figure 29 Caution If the plates do not open enough during trimming action even when the assembling is co...

Page 21: ...ition of the pulley s thread take up lever with the position Then rotate the timing pulley to align the bed base point with the timing pulley s base point Hang the timing belt in this position After adjustment when the feed dog comes down and the needle goes up check whether the needle tip matches the needle plate upper side at the moment that the feed dog upper side and the needle plate upper sid...

Page 22: ...w so that like in Figure 35 the hook edge falls exactly at the center of the needle center when the needle bar is raised 2 4mm from its lowest position When this is done the hook edge will be placed at about 1 1 5 mm above from the upper shaft of the needle thread hole B In case of the 797 series if the height of the left and right needles are not the same or if the Figure 35 situation where the n...

Page 23: ...eedle plate groove Like in Figure 39 the normal distance between the hook stopper and the upper side of the needle plate groove is 1 3mm This distance is adjusted by the thickness of the space washer that lies under the hook When the hook gear fixing screw is removed for repair or replacement make sure to put back the space washer that was used originally The thickness of the washer may differ by ...

Page 24: ...w fixing nut and adjust the face plate oil level adjustment screw After adjustment tighten the fixing nut See Figure 43 1 When stopping the left needle bar Place the needle bar trimming direction lever to the L left position 2 When stopping the right needle bar Place the needle bar trimming direction lever to the R right position 3 When switching to two needle sewing Vertically press the needle ba...

Page 25: ...inished make sure to turn the machine pulley to place the trimming cam in the right position so that the roller can enter the complementary straight line range b Press down the trimmer shake linkage to make the roller come inside the trimming cam Adjust the holder to make the right equal point of the roller adhere smoothly to the right inside of the cam s complementary straight line and the left e...

Page 26: ...mer shake linkage has returned to its up position after trimming action B First loosen the fixing screw of the movable knife shaft right hold the initial assembling angle of the crank right to be about 15 30 to the left from the perpendicular line drawn to its center To make sure that this position is maintained adjust the length of the ball joint linking bar which comes assembled to trimmer shake...

Page 27: ... plate Holding the hook with the hand manually operate trimming movement so that the movable knife edge is matches the stopper front side Loosen the fixing screw of the movable knife shaft eccentric bushing In the lower side hole of the eccentric bushing stick in a thin driver or adequate pin and turn right and left This will make the position of the movable knife shaft change hence changing the d...

Page 28: ...e adhesion conditions on the picture Correcting the adhesive conditions of movable and fixed knives Like in Figure 49 operate manual trimming movement with color ink on the movable knife edge By checking the ink trace remaining on the movable knife the surface adhesion condition of the movable fixed knives can be tested If the surface adhesion is not very good same method is used to adjust the ten...

Page 29: ...o be adjusted slightly use the ball joint linking bar If only the movable knives are to be adjusted use the linking rod D Adjusting lower thread holder See Figure 51 The position of lower thread holder is set by fixed blade and bolt Like in the picture loosen the bolt and place the lower thread holder edge at the lower side of the movable knife about 8mm apart from the movable knife edge Make sure...

Page 30: ...ase check the edge condition of the fixed blade If the edge of the knife is too dull sharpen the edge using oil stone or sand paper See Figure 53 17 Replacing movable knife and fixed blade See Figure 54 1 Lift the presser foot and open the slide plate lefts right and front 2 Disassemble the needle plate 3 Loosen the fixing screw to disassemble the washer fixed blade and lower thread holder 4 Loose...

Page 31: ...e wiper 6 When the wiper is in waiting position the distance between the wiper edge and the presser bar equal point should be about 3 mm To do so loosen the clamp screw and vertically adjust the stopper Depending on the thread type there are cases where the thread cannot be hung to the wiper edge Hence it is necessary to bring the wiper into the range of the needle where the thread from the sewing...

Page 32: ...urn it towards the arrowed direction for removal KM 757 series 4 Lift the presser bar lifter to raise the presser foot 5 Remove the presser foot 6 Remove the needle plate 7 Disassemble the feed dog 8 Lay down the sewing machine Adjusting the left right hook base When replacing with a wider or narrower gauge than the needle width in use the hook edge and needle distance may not fit correctly In thi...

Page 33: ...on and height of needle Needle Feed dog timing Gap between needle and hook Threading method Needle Direction and height of needle Upper thread tension Lower thread tension Thread take up stroke Hook Feed dog Needle plate Thread tension Thread take up spring tension Gap between opener and hook Direction and height of needle Needle Threading Hook timing Gap between the needle and the hook Remaining ...

Page 34: ...ap between the movable knife and the hook Check the tension of fixed knife Direction of the needle Blade side of movable and fixed knives Trimming cam timing Thread release stroke Trimming timing Opening of the thread tension adjusting plate Tension of auxiliary thread tension adjustment assembly Thread take up stroke Thread release adjustment volume on the control box Readjust the movable knife s...

Page 35: ...35 5 Table Drawing ...

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