JUKI MF-7900 Series Engineer'S Manual Download Page 18

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4. Standard adjustment

(1) Threading the machine head

WARNING :

Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the

sewing machine.

Standard adjustment

When using more stretchable

thread

❷

When covering thread is excessively

loosened =

When covering thread is excessively

loosened even after passing

When covering thread is

excessively tense =

Broken lines

when stretcher thread

is used

When using less stretchable

thread

Broken line

when using more stretchable thread

❸

❶

❹

❶

❷

❹

❸

Summary of Contents for MF-7900 Series

Page 1: ...70002000 No E406 01 ENGINEER S MANUAL MF 7900 Series High speed Cylinder bed Top and Bottom Coverstitch Machine MF 7900D Series High speed Semi dry head Cylinder bed Top and Bottom Coverstitch Machine...

Page 2: ...d other important information which are not covered in the Instruction Manual When carrying out the maintenance work on the sewing machine be sure to refer also to the Instruction Manual and the Parts...

Page 3: ...eedle changing bobbin changing or oiling and cleaning Electrical shock danger label DANGER This indication is given where there is an immediate danger of death or serous injury if the person in charge...

Page 4: ...eath JUKI assumes no responsibility for damages or personal injury or death resulting from the machine which has been modified or altered Education and training 1 In order to prevent accident resultin...

Page 5: ...rth cable in order to prevent accident caused by earth leakage IV Motor 1 Be sure to use the specified rated motor JUKI genuine product in order to prevent accident caused by burnout 2 If a commercial...

Page 6: ...t that can result in personal injury or death 9 Be sure to periodically clean up the air vent of the fan and inspect the area around the wiring in order to prevent fire accident of the motor 10 In ord...

Page 7: ...to protect against accident that can result in personal injury In addition be sure to select appropriate tools 3 In prevention of accident that can result in personal injury make sure after the comple...

Page 8: ...ne parts when replacing any of the machine parts JUKI assumes no responsibility for any accident caused by any part other than JUKI genuine one In addition in the event you cannot replace parts within...

Page 9: ...pecified After the completion of assembly work be sure to check that screws and nuts are not loosened before starting test run 6 In prevention of accident that can result in personal injury make sure...

Page 10: ...aning threading or replacing the needle of the sewing machine 5 Never operate the sewing machine with the ground wire for the power supply removed so as to ensure safety 6 Be sure to turn OFF the powe...

Page 11: ...different from the designated one The direction of rotation of the sewing machine is clockwise as observed from the pulley side Be careful not to rotate it in reverse direction When operating the sewi...

Page 12: ...x...

Page 13: ...0 Series How to use the timing gauge 60 5 UT51 52 Solenoid type thread trimmer 62 1 Installing the SC 921 62 2 Adjusting and setting SC 921 63 3 Adjusting the looper thread trimmer mechanism 68 4 Adju...

Page 14: ...ing the looper thread trimmer mechanism 158 1 Adjusting the looper thread trimmer air cylinder 158 2 Adjusting the engagement of the lower knife 158 3 Initial position of the looper thread trimmer mec...

Page 15: ...ed Micro adjustment 8 Stitch length 0 9 mm to 3 6 mm can be adjusted up to 4 5 mm 9 Needle UY128GAS 9S to 12S standard 10S Equivalent to Nm65 to Nm80 standard Nm70 10 Needle bar stroke 31 mm 33 mm whe...

Page 16: ...indows Differential lock nut Oil hole cap Micro adjustment knob Micro lifter Finger guard Needle thread silicon oil lubricating unit Rocking thread take up Thread guide No 1 Front cover Upper pulley N...

Page 17: ...MF 7900D Series 1 The table shows the numbers when a 3 phase 2 pole 400 W clutch motor 1 2 HP is used 2 The commercially available motor pulley near to the counted value is designated since the outsi...

Page 18: ...ing machine Standard adjustment When using more stretchable thread When covering thread is excessively loosened B When covering thread is excessively loosened even after passing B C When covering thre...

Page 19: ...stretchable thread wooly thread or the like the threading as given below does not make thread stretch and neat seams can be obtained 1 Do not pass thread through spreader auxiliary thread ten sion Ref...

Page 20: ...bar is in its lowest position Flush 3 Timing of the rocking thread take up 1 It is the standard timing that rocking thread take up is in its lowest position as well when the needle bar is in its lowe...

Page 21: ...ollar is 8 mm Caution 1 When loosening setscrew in rocking thread take up ball arm there is a case where rocking thread take up rotates by its weight After the adjustment be sure to check the rocking...

Page 22: ...Adjusting the needle thread loop by the eccentric cam WARNING Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Standard adjustment C...

Page 23: ...eccen tric cam and the relation between the eccentric cam and the needle thread loop is shown in the following table Size of needle thread loop A Move forward B Move backward Loop becomes smaller Loo...

Page 24: ...ons from the top surface of needle thread guide base to the bottom end of the hole are as follows Left needle A 29 mm Middle needle B 17 mm Right needle C 5 mm A 29 mm B 17 mm C 5 mm C B A 2 Adjusting...

Page 25: ...not applied to threads 2 Adjusting the position of needle thread guide base and silicon container thread guide 1 Loosen setscrews and and move silicon container thread guide up or down to adjust the h...

Page 26: ...needle bar thread take up thread receiver in case of standard seams 1 It is the standard that the height of needle bar thread take up thread receiver is in the position where the bottom end of thread...

Page 27: ...ver with setscrew Since larger thread loops are formed by raising needle bar thread take up receiver it is necessary to adjust the needle bar thread take up receiver while checking the state of thread...

Page 28: ...of spreader thread guide aligns with the bottom end of slot B of spreader thread take up when spreader thread take up is in its highest position Adjust the relation of the position so that thread is...

Page 29: ...take up and adjusting the position of spreader thread take up adjust so that length of rocking thread take up 83 mm does not change When the relation of position between spreader thread take up and t...

Page 30: ...read hooking section reaches to the front of left needle the clearance between the spreader and the left needle is 0 1 to 0 3 mm 0 1 to 0 3 mm 4 5 to 5 5 mm 17 0 to 18 0 mm Extreme left position 3 Pro...

Page 31: ...otch B in the main shaft aligns with notch C in spread er eccentric cam When changing turn the upper pulley and change with spreader eccentric cam fixed C B Height of the spreader is improp er stitch...

Page 32: ...ed between spreader and spreader thread guide is 0 4 to 1 0 mm 2 It is the standard that the clearance provided between spreader thread guide and needle clamp thread guide is 0 8 to 1 2 mm 3 Lateral p...

Page 33: ...he needle clamp thread guide and spreader thread guide to 0 8 to 1 2 mm 3 For the lateral direction align the hole of needle clamp thread guide to the prolonged line of the slot of spreader thread gui...

Page 34: ...nsion A is the same as dimension B when the needle bar goes up from the lower dead point the blade point of looper passes the rear of needle and the left end of right nee dle aligns with the blade poi...

Page 35: ...nced In this case loosen setscrews in the sprocket and finely turn upper pulley in the reverse direction 2 In case dimension A when the looper advances going is larg er than dimension B when the loope...

Page 36: ...om top end of looper to the center of needle bar is 5 9 mm regardless of the needle gauge when looper is in the extreme right position 2 Returning amount of looper for each gauge dimension A Unit mm 2...

Page 37: ...mm when the top end of looper comes to the center of left needle from the extreme right position After the adjustment fix the looper holder with setscrew in the looper holder Blade point B of the loo...

Page 38: ...e extreme right position and protrudes from the left end of left needle by approximately 1 to 1 2 mm dimension B Dimension B standard needle size 10S Reference Dimension C height of left needle from t...

Page 39: ...nd adjust the height of the needle bar 2 After adjusting the height equally adjust the clearance A be tween needle and needle hole D in the throat plate and fix the needle bar with setscrew in the nee...

Page 40: ...extreme left position in the standard looper motion locus 2 Longitudinal motion timing of the looper 1 The standard position of the cam is the po sition where the engraved marker line G on looper long...

Page 41: ...on C the timing is advanced and in the direction D the timing is retarded Caution It is possible to change the locus of the looper How ever do not excessively change it from the standard position with...

Page 42: ...tion to the center of right needle 3 Pressing amount of the rear needle guard It is the standard that when top end of the looper comes from the extreme right position to the center of right needle the...

Page 43: ...end of looper does not come in contact with the needle 3 When turning the rear needle guard cam in the direction of rotation the timing of rear needle guard is advanced and when turning it in the rev...

Page 44: ...front needle guard 1 Height of the front needle guard It is the standard position that the height of front needle guard is positioned higher by 3 3 0 5 mm than rear needle guard 2 Clearance provided b...

Page 45: ...h setscrew so that the clearance pro vided between the needle and front needle guard is 0 2 to 0 5 mm when looper moves from the extreme right position to the left and passes the rear side of the resp...

Page 46: ...1 Height of the feed dog It is the standard that the height of feed dogs main feed dog and differential feed dog is 1 0 1 mm from the top surface of the throat plate when feed dogs and are in the high...

Page 47: ...ction of A the feed dog moves in the direction of C and is in the front up state 3 When turning collar in the direction of B the feed dog moves in the direction of D and is in the front down state 4 A...

Page 48: ...ts caused by abrupt start of the sewing machine Standard adjustment 3 Lateral position of the feed dog It is the standard of the lateral position of the feed dog that the left and right clearances A o...

Page 49: ...arances A provided between the throat plate and the feed dog are adjusted to be parallel and equal fix the rocking bar pressers with setscrew in rocking bar presser right and setscrews in rocking bar...

Page 50: ...of the slot of the throat plate to the front face of the main feed dog is 0 6 0 2 mm at the position where the main feed dog travels to the extreme front position operator s side when feed momentum i...

Page 51: ...the main feed lever 3 Adjusting the longitudinal position of the differential feed dog Adjust the differential feed ratio to 1 1 and loosen setscrews in differential feed lever Adjust the clearance pr...

Page 52: ...ble for the standard stitch length to adjust up to 0 9 to 3 6 mm Turning feed adjust knob clockwise increases the stitch length and turning it counterclockwise de creases the stitch length 2 Changing...

Page 53: ...d ratio to 1 0 6 to 1 1 1 Remove setscrew in differential feed link Tighten differential feed link into screw hole C with setscrew which has been removed 3 The differential feed ratio can be changed f...

Page 54: ...feed locus 1 Changing the feed driving motion The timing of feed driving eccentric cam of the feed mechanism can be retarded from the timing obtained by the standard adjustment 2 Changing the feed ro...

Page 55: ...ry to make sure that a clearance is provided between feed driving ec centric cam and positioning cam before check ing the timing 2 Changing the feed rocking motion 1 Loosen two setscrews of the feed r...

Page 56: ...s in contact with height adjust ment screw Dimension A 8 mm in case of needle gauge 5 6 mm without top covering 5 mm in case of needle gauge 5 6 mm with top covering A 2 Position of the lifter connect...

Page 57: ...d the bottom face of the presser foot comes in close contact with the throat plate When the position of the press er foot is too high it comes in contact with the spreader and breakage stitch skipping...

Page 58: ...o as to prevent accidents caused by abrupt start of the sewing machine Standard adjustment 1 Micro lifter Adjust the micro lifter in accordance with sewing conditions for use Major applicable process...

Page 59: ...e and coun terclockwise the presser bar lifting lever is pressed down to lift the presser foot Adjust the height of the micro lifter according to the sewing condition Caution In the case the micro lif...

Page 60: ...looper thread cam when needles come down and the top end of left needle aligns with the bottom surface of looper Then tighten set screws in the looper thread cam to fix the looper thread cam 2 Adjusti...

Page 61: ...ecreased in case of 2 needle machine or the like loosen screws move upward thread guides and and tighten screws to fix them A Decrease B Increase 3 Preventing thread winding around the looper thread c...

Page 62: ...ustment value of balloon WARNING Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Standard adjustment Thread Lower by 6 mm 29 mm 17 m...

Page 63: ...he looper Adjusting the looper thread cam Adjust so that the looper thread comes off the looper thread cam when the top end of the lowering left needle comes to the middle between the lower end face a...

Page 64: ...g the sewing machine for the first time Oil used JUKI CORPORATION GENUINE OIL 18 Caution Do not use oil addition agent since deterioration of lubricating oil or machine trouble will be caused Remove o...

Page 65: ...ndow even when oil filter is replaced with a new one remove four setscrews in the oil pan remove oil pan and tilt the machine head to the rear up to the position where pipe connecting joint screw can...

Page 66: ...RNING Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Standard adjustment 3 Oiling MF 7900D only No oiling 4 Replacing the lubricati...

Page 67: ...e will be ex pelled resulting in mechanical failure 4 Replacing the lubricating oil In case of the new sewing machine replace the lubricating oil JUKI CORPORATION GENUINE OIL 18 with new one after usi...

Page 68: ...tart of the sewing machine Standard adjustment 1 Changing the needle bar stroke 31 mm 33 mm Needle bar stroke is 31 mm in the state that notch mark F on the edge of the eccentric pin is lo cated on th...

Page 69: ...t At the time of needle bar stroke 33 mm notch mark is on the side away from the center of main shaft Caution There is a groove to fit when eccentric pin is turned by 180 at the fitting section of ecc...

Page 70: ...e looper moves from the extreme right position to the left and top end D of looper protrudes by approximately 1 mm from the left end of left needle remove rubber cap in the face plate and tighten the...

Page 71: ...looper comes from the extreme right position to the center of right needle the clearance provided between the right needle and top end of the looper is 0 to 0 05 mm when top end of the looper comes to...

Page 72: ...dle bar stroke is changed be sure to perform to adjusting the height of the spreader of 4 7 Adjusting the spreader 1 Height from the top surface of throat plate to spreader is 10 0 to 10 5 mm 2 Cleara...

Page 73: ...59 Adjustment procedures Results of Improper adjustment 1 Refer to 4 7 Adjusting the spreader...

Page 74: ...rning amount even when the needle gauge is the same Use the gauge on which MF 7500 Series is stamped for MF 7700 or that on which MF 7900 Series is stamped for MF 7800 Unit mm MF 7500 Series Top surfa...

Page 75: ...e between the needle and the spreader Insert the gauge between the left needle and the spreader when the spreader starts to return from the extreme left position to the right and comes nearest to the...

Page 76: ...rupt start of the sewing machine 1 Wiring Installing procedure of the exclusive cord for MF Connect the exclusive cords for MF to the respective designated connectors as follows Thread trimmer sensor...

Page 77: ...machine head 1 Refer to the Engineer s Manual of SC 920 SC 921 5 9 SC 921 Func tion setting and call up the function setting No 95 2 The type of machine head can be se lected by pressing switch switc...

Page 78: ...430 Ld54 4000 4500 23 DMN 5420 Mn54 4000 5000 24 DLN 5410 Ln54 4000 5000 25 DLN 5410 H J Ln5H 3500 4000 26 DLM 5400 LM54 4000 4500 27 LZ 2280 Z280 4000 5000 28 LZ 2280A Z80A 4000 5000 29 LZ 2284C Z84C...

Page 79: ...displayed on the indicator The value is the reference value 4 In this state align the marker line F of the handwheel with the concave E of the machine head shown in the figure 5 Press switch to finish...

Page 80: ...he setting of the function setting No 74 to 1 thread trimming 0 UP DOWN position Thread trimmer safety device error occurs unless the setting is changed and it is impossible to operate the sewing mach...

Page 81: ...of the auto lifter function WARNING When the solenoid is used with the air drive setting the solenoid may be burned out So do not mistake the setting When the auto lifter device AK is attached this fu...

Page 82: ...otect against possible personal injury due to abrupt start of the machine be sure to start the following work after turning the power off and ascertaining that the motor is at rest Standard adjustment...

Page 83: ...per thread trimmer solenoid is 17 5 0 5 mm 2 When adjusting the stroke loosen setscrew of collar and move collar to the right or left to adjust 3 After adjusting the stroke loosen screw from the lower...

Page 84: ...rtaining that the motor is at rest Standard adjustment 2 Adjusting the looper thread trimming knife 1 Adjusting the Lower knife 2 Adjusting the position of clamp pressure adjusting spring 3 Adjusting...

Page 85: ...n screws and and adjust the position of upper knife so that the engagement of the upper knife with the lower knife is 0 5 mm when lower knife moves to the ex treme right 2 At the same time adjust so t...

Page 86: ...after turning the power off and ascertaining that the motor is at rest Standard adjustment 5 Initial position of the looper thread trimmer mechanism 6 Adjusting the stopper 7 Adjusting the height of...

Page 87: ...looper and clamp pressure adjust ing spring when the counter knife is located at its leftmost position forward end 7 Adjusting the height of the lower knife 1 When the needle is positioned at its uppe...

Page 88: ...e machine be sure to start the following work after turning the power off and ascertaining that the motor is at rest Standard adjustment 9 Adjusting the longitudinal position of the blade point of low...

Page 89: ...hen the clearance between the right hand edge of looper and the blade point of lower knife is 9 mm 3 Loosen nut move lower knife holder to and fro and ad just the position of the blade point of lower...

Page 90: ...st possible personal injury due to abrupt start of the machine be sure to start the following work after turning the power off and ascertaining that the motor is at rest Standard adjustment 10 Adjusti...

Page 91: ...the looper thread trimmer device returns to its home position 1 Loosen setscrews 2 Adjust switch plate so that LED of thread trimmer sensor lights up in the state that the thread trimmer device is fu...

Page 92: ...start the following work after turning the power off and ascertaining that the motor is at rest Standard adjustment 11 Adjusting the disk rise 12 Adjusting the thread release hook A Clearance between...

Page 93: ...e Then tighten setscrew 2 Loosen setscrew move the position of thread release hook up or down and the thread remaining length at the start of sewing can be adjusted Caution 1 When the thread remaining...

Page 94: ...r mechanism WARNING To protect against possible personal injury due to abrupt start of the machine be sure to start the following work after turning the power off and ascertaining that the motor is at...

Page 95: ...s highest position 2 When hinge screw is lowered moving knife lowers togeth er 3 Adjust so that the hook of moving knife enters the recess in the top face of spreader to be brought to the position whe...

Page 96: ...ing WARNING To protect against possible personal injury due to abrupt start of the machine be sure to start the following work after turning the power off and ascertaining that the motor is at rest St...

Page 97: ...pensa tion of SC 921 When performing the machine type setting it is set to be stopped at a position described above 2 UP position 1 UP position of the needle is the position that the mark C on the mac...

Page 98: ...trimmer Auto lifter Top and bottom thread trimmer Auto lifter Air blow type wiper MC37 MC40 Air consumption dm3 min ANR Compressed air MPa UT55 0 7 0 5 456 UT56 182 0 5 637 UT57 0 7 0 5 182 456 637 1...

Page 99: ...s follows Thread trimmer sensor cord CN42 Thread trimmer cord CN36 Presser lifter cord CN37 9P connector coming from the motor CN30 Pedal sensor cable CN34 Motor fan cord CN55 Connecting the connector...

Page 100: ...abrupt start of the machine be sure to start the following work after turning the power off and ascertaining that the motor is at rest In addition cut the air supply from air compressor Standard adju...

Page 101: ...air regulator 2 Use the air pressure at 0 5 MPa 5 kgf cm2 3 Draw up regulator knob turn knob and adjust the pointer to 0 5 MPa to adjust the air pressure 4 After the adjustment press downward regulat...

Page 102: ...the power is ON never touch the switches other than the necessary one so as to prevent accidents caused by the malfunction of switches Standard adjustment 1 Adjusting the thread trimmer air cylinder...

Page 103: ...Perform the work with the needle bar at the highest position when actuating the thread trimmer mecha nism by hand 3 Adjusting the speed of looper thread trimmer Speed of the looper thread trimmer dev...

Page 104: ...rt the following work after turning the power off and ascertaining that the motor is at rest In addition cut the air supply from air compressor Standard adjustment 1 Adjusting the engagement of knives...

Page 105: ...osition Then tighten screws and Adjust the moving knife vertically so that a clearance of 0 5 mm is provided between the recess section of spreader and the moving knife and laterally so that the movin...

Page 106: ...formed while the power is ON never touch the switches other than the necessary one so as to prevent accidents caused by the malfunction of switches Standard adjustment 1 Installing the air blow wiper...

Page 107: ...position 2 After the adjustment temporarily tighten setscrews 3 Supply air from the air compressor and turn the power ON 4 When the back part of the pedal of sewing machine is de pressed the presser g...

Page 108: ...sure to start the following work after turning the power off and ascertaining that the motor is at rest In addition cut the air supply from air compressor Standard adjustment 1 Adjusting the clamp sp...

Page 109: ...ative to mounting base and a clearance of 4 mm is provided between them In this state tighten screw 4 Adjust wiper so that its top end is spaced 15 mm from the center of the needle bar and its height...

Page 110: ...ing WARNING To protect against possible personal injury due to abrupt start of the machine be sure to start the following work after turning the power off and ascertaining that the motor is at rest St...

Page 111: ...pensa tion of SC 921 When performing the machine type setting it is set to be stopped at a position described above 2 UP position 1 UP position of the needle is the position that the mark C on the mac...

Page 112: ...98...

Page 113: ...Speed of stitch at the delivery 4 500 sti min at the time of intermittent operation Needle gauge 3 needle 5 6 mm 6 4 mm 2 needle 4 0 mm 4 8 mm Differential feed ratio 1 0 9 to 1 1 8 stitch length les...

Page 114: ...OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Standard adjustment 1 Adjusting the upper knife pressure 2 Adjusting the lateral positio...

Page 115: ...re Move thrust collar to the right in direction B Then tight en setscrew Loosen setscrew of thrust collar once Tighten setscrew to fix thrust collar with pressed against the end face of bushing by the...

Page 116: ...before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Standard adjustment 3 Adjustment procedure of engagement amount of knives 4 Replacement procedure of up...

Page 117: ...he direction of the arrow with knife shaft pressed in the direction of the arrow 3 Insert a new lower knife in the groove of lower knife holder and tighten setscrew in the lower knife presser plate in...

Page 118: ...pper knife stroke 6 Adjusting the engagement angle of the knife B A Clockwise Horizontal position C D E F D Standard adjustment angle E Angle adjusted for hard to sew materials F Angle adjusted when t...

Page 119: ...clockwise depending on the knife sharpness to adjust it 2 After the adjustment of the knife sharpness tighten adjusting lever setscrew 3 After the adjustment of the engagement carry out 7 2 1 Adjustin...

Page 120: ...106...

Page 121: ...n device with a pedal connecting rod air switch Applicable machines MF 7900 H22 23 and MF 7900 E11 pro vided with the control box SC 921 MF 7900 H22 23 and MF 7900 E11 Major features At the moment whe...

Page 122: ...NG Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Standard adjustment 1 Installing the connecting rod MC40 2 Adjusting the connecti...

Page 123: ...usting the connecting rod air valve MC40 1 Loosen setscrew in the valve holder and adjust the position of air valve properly The standard position of the air valve is obtained when the valve pin light...

Page 124: ...as to prevent accidents caused by abrupt start of the sewing machine Standard adjustment 3 Assembling the cloth chip and chain off thread suction device 4 Connecting the flexible hose 550 mm Front of...

Page 125: ...ible hose 1 Cut flexible hose to a length required for connection on side A In case of MF 7900 H22 23 attach it to cloth chip pipe asm and waste remover body In case of MF 7900 E11 attach it to pipe a...

Page 126: ...g the work so as to prevent accidents caused by abrupt start of the sewing machine Standard adjustment 5 Adjusting the suction force 6 Installing the waste bag A B 30 mm 50 mm Drawing of the table rea...

Page 127: ...ousing with screw washer and nut In this state however plate rotates To stop the state insert stop plug into the hole of waste bag housing and waste bag plate so that plate faces the direction as show...

Page 128: ...to prevent accidents caused by abrupt start of the sewing machine Standard adjustment 7 Piping the air components Piping diagram for the MC37 A B OUT IN MF 7900 E11 A B MF 7900 H22 23 A B Piping diag...

Page 129: ...ng the air components 1 Fix solenoid valve under the table with wood screws sup plied as accessories 2 Refer to the piping diagram shown for piping the air compo nents Caution The air tube is slightly...

Page 130: ...Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Standard adjustment 8 Installing procedure of the exclusive cord for MF Installing...

Page 131: ...alve cords of MC to connector 36 Connecting No No 14 Black and No 7 Black Solenoid valve cord of MC and thread trimmer cord CN36 Caution Fig 1 shows the connection of connector of UT57 and MC37 as an...

Page 132: ...118...

Page 133: ...hen lift of presser foot is 4 mm PL12 6 3 mm PL13 8 0 mm When lift of presser foot is 5 mm PL12 7 0 mm PL13 8 7 mm When lift of presser foot is 6 mm PL12 7 8 mm PL13 9 5 mm Presser pressure 50N to 150...

Page 134: ...ment WARNING Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Standard adjustment 1 Adjusting the roller presser pressure 2 Adjusting...

Page 135: ...ng regulator to the left counterclockwise when decreasing the presser pressure 2 Adjusting the feed amount of the roller 1 Loosen screw when adjusting the feed amount of the roller Feed amount is decr...

Page 136: ...Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Standard adjustment 3 Adjusting the roller presser lifter 4 Assembling the rear roll...

Page 137: ...ust with two screws so that the clearance between press er lifter lever link short and hinge screw is 0 5 mm when performing the presser lifting in the state that the top roller is lowered 4 Assemblin...

Page 138: ...NING Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Standard adjustment 5 Adjusting the clutch tension spring 6 Grease lubrication...

Page 139: ...se 4 After the adjustment tighten cap nut Caution The standard of the spring pressure is to such an ex tent that clutch tension spring turns with the small force of your finger after tightening cap nu...

Page 140: ...e power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Standard adjustment 7 Feed timing of the roller 8 Adjusting the clearance between the gear roll...

Page 141: ...s in puller eccentric cam to adjust When the cam is moved in the direction of C the start of the roller is advanced and when it is moved in the direction of D the start of the roller is de layed 8 Adj...

Page 142: ...table up to 4 5 mm Noise Equivalent continuous emission sound pressure level LpA at the workstation A weighted value of 78 5 dB Includes KpA 2 5 dB according to ISO 10821 C 6 2 ISO 11204 GR2 at 4 000...

Page 143: ...and and move moving knife and counter knife to the right and left to adjust the distance The knife will not move unless setscrews and are loos ened 2 After the adjustment tighten setscrew and setscre...

Page 144: ...Caution 1 The extent of the adjustment of the angle of mesh is until marker dot A is turned counterclockwise to reach the horizontal position If the lever is turned beyond the above the angle between...

Page 145: ...ush with the throat plate or slightly lower than the throat plate Caution When knife holder is removed per form the adjustment of engagement again A Adjust the position of cloth guide in accordance wi...

Page 146: ...sser foot for ad justment Loosen setscrew and move tape rubber guide base to the right and left to adjust the position of the tape WARNING To protect against possible personal injury due to abrupt sta...

Page 147: ...l bottom roller plate with three wood screws Reference For the installing position of the bottom roller plate refer to the drawing of the table 1 Installing the guide roller 1 Adjust presser guide asm...

Page 148: ...roller plate base refer to the drawing of the table 2 Install rear roller asm to rear roller plate base with screw M8 washer and clamp lever 5 Installing the suction pipe 1 Fix suction pipe retaining...

Page 149: ...d tighten screw 3 Loosen screw of collar of the intermediate roller and move collar to the right or left in accordance with the elastic belt width At this time make sure that the elastic belt is put s...

Page 150: ...the length of it and tighten clamp lever 3 Adjusting the position of the bottom roller 1 Adjusting the lateral position Loosen three screws adjust the bottom roll er so that the elastic belt is put s...

Page 151: ...support bracket and center B of the roller shaft is approx 30 mm Then clamp lever Fig 2 3 Adjusting the lateral position Loosen screw adjust the left end face of col lar to the right hand side of the...

Page 152: ...ight hand side of the elastic belt and tighten screw 2 Adjusting the angle and length Loosen screw and adjust presser guide so that the distance from the bottom of installing section is approx 41 mm a...

Page 153: ...just presser bar so that the clearance between cloth presser and knife is 0 5 mm Then tighten screw and screw Fig 1 2 Adjusting the vertical position Loosen screw and adjust bracket to the position of...

Page 154: ...oosen screw and adjust stopper to the position before it comes in contact with lever Then tighten screw 5 Adjusting the presser plate pressure Adjust the presser pressure by loosening screw and turnin...

Page 155: ...knife is fixed in the aforementioned position which is lower than the throat plate To use moving knife again slightly depress lever Moving knife will be brought to the previous position and lever and...

Page 156: ...1 1 8 Stitch length less than 2 5 mm Provided with micro differential feed adjustment mechanism Micro adjust Stitch length 0 9 to 3 6 mm Adjustable up to 4 5 mm Binder open close amount 40 mm Needle...

Page 157: ...close device apply grease supplied with the device to section B Exclusive grease Unirex N2 JUKI part No 13525506 3 Installing the lever asm Install lever asm with setscrew slotted head screw black scr...

Page 158: ...the chain is not proper abnormal friction of the chain occurs So install the chain with care 6 Connecting the chain After installing roller asm fit the chain to the groove of the roller put S hook in...

Page 159: ...binder with collar 1 Adjusting the position of the binder Perform the adjustment of the position of binder with screws WARNING To protect against possible personal injury due to abrupt start of the ma...

Page 160: ...talling the binder open close device Place spacer and install binder open close device Insert air tubes into joints of binder open close knee switch asm Fix air tube with air tube holder WARNING To pr...

Page 161: ...Installing the air regulator Install the air regulator asm under the table with wood screws WARNING To protect against possible personal injury due to abrupt start of the machine be sure to start the...

Page 162: ...of binder loosen the nut of speed controller located on the operator side and turn the adjust ment screw After the adjustment tighten nuts of speed con trollers and 4 Adjusting the air regulator 1 Ins...

Page 163: ...tighten wood screws Place downward the flat plane of the slide shaft so that the knobs can be fixed 3 Enter block asm to slide shaft and tighten screw M8 3 Installing the front roller 1 Enter front ro...

Page 164: ...elastic band straight to the front roller 1 Loosen screw adjust collar to the position of the right hand end of the elastic band and tighten screw Caution Do not excessively tighten screw Deformation...

Page 165: ...that the elastic band is put straight and tighten three screws 2 Adjusting the vertical position Loosen clamp lever adjust the position so that the elastic band is appropriately in accordance with th...

Page 166: ...S to 12S standard 10S Needle bar stroke 31mm 33 mm when the eccentric pin is changed over Dimensions Height 450 x Width 456 x Length 299 Weight 45 kg With pneumatic type thread trimmer Lift of presser...

Page 167: ...l air regulator asm under the table with wood screws 1 Install manifold asm on the table with wood screw WARNING To protect against possible personal injury due to abrupt start of the machine be sure...

Page 168: ...34 8 Insert motor fan cord into connector CN55 9 Insert 8P cord into connector CN56 Caution Be sure to securely insert the respective connectors after checking the inserting directions since all conne...

Page 169: ...can be selected by pressing switch switch Refer to the MACHINE HEAD LIST on the separate sheet or the Instruc tion Manual for the machine head of your sewing machine for the type of the machine head...

Page 170: ...0 5 MPa to ad just the air pressure 4 After the adjustment press downward knob of regulator 5 When drainage is collected at section A of regulator during using press drain cock to discharge the drain...

Page 171: ...g threading illustrations 6 mm Turn the thread holding device to counterclockwise looper thread remaining after thread trimming is in creased Turn it to clockwise looper thread remaining after thread...

Page 172: ...d move collar the right or left to adjust 1 Loosen screws and and adjust the posi tion of upper knife so that the engagement of the upper knife with the lower knife is 0 5 0 2 mm when lower knife move...

Page 173: ...bar Perform the adjust ment by loosening the nut Caution 1 Perform the work with the needle bar at the highest position when actuating the thread trimmer mechanism by hand 2 Perform the adjust ment b...

Page 174: ...le bar at the highest position when actuating the thread trimmer mechanism by hand 2 After the adjustment actuate plunger by hand and confirm that the thread trimmer de vice smoothly works 1 Bring the...

Page 175: ...stopper 1 Adjust the position of stopper so that a clearance of 0 3 to 1 mm is provided between looper and clamp pressure adjusting spring when the upper knife is located at its leftmost position for...

Page 176: ...device returns to its home position 1 Loosen setscrews 2 Adjust switch plate so that LED of thread trimmer sensor lights up in the state that the thread trimmer device is fully returned to its home p...

Page 177: ...of the machine be sure to start the following work after turning the power off and ascertaining that the motor is at rest WARNING To protect against possible personal injury due to abrupt start of th...

Page 178: ...indicated on display section with a blip The value is the reference value 4 In this state give the pulley of the machine head another turn by hand to align marker line on the hand pulley with recess i...

Page 179: ...ssary to take a note of the numeric value shown on display section since it is used for 9 Setting the raveling prevention pa rameter Caution If you press switch in this state the upper stop position o...

Page 180: ...isplayed when the descending left needle tip is aligned with the center of the looper is 90 Subtract the former value 5 from the latter value 90 i e 90 5 85 Press switch or switch to change the value...

Page 181: ...n setscrews and Adjust the clearance provided between the left needle and the thread hook to 0 to 0 05 mm when the left needle and the top end of thread hook are aligned in lateral direction Then tigh...

Page 182: ...tion A the thread hanging hook moves to the direction C sliding it in the direction B the thread hook moves to the direction D Move the air cylinder base general asm so that the clearance between the...

Page 183: ...ws at a position that setscrews is pressed against to the direction E anti operator s side Caution If setscrews are not tightened with pressed in direction E anti operator s side the thread hook relea...

Page 184: ...eady applied Never use any other type of grease 2 In ordinary usage the replenishment of grease is not required In the case of rigorous usage however periodic replenishment once every one or two years...

Page 185: ...fill this groove section with JUKI Grease A 2 There is a grease groove inside the metal of needle bar crank rod asm No 4 When the needle bar connection No 6 is pulled out fill this groove section with...

Page 186: ...of the needle clamp apply Loctite 242 to this section and set it in the needle bar Caution There is a grease groove inside the spreader lon gitudinal metal No 22 When the spreader longi tudinal shaft...

Page 187: ...ad breakage In case needle exchanger or needle guard is worn out replace it with the new part 1 4 Needle 4 A Too thin needle for the thread used Replace it with an appropriate needle 1 5 Needle heat 5...

Page 188: ...ong tension of looper thread Reduce the thread tension while checking to see the tension balance against the needle thread top covering thread 2 4 Thread 4 A Poor quality and weakness of thread Replac...

Page 189: ...rect position Refer to the standard adjustment figures 3 5 Needle thickness No 5 A Too thin needle for fabric used Use thicker needle 3 6 Thread tension 6 A Needle thread tension is too strong Reduce...

Page 190: ...d Use nipper 1 D Needle thread guide rod D 1 Height is too high Correct the height to appropriate height 1 E Needle height E 1 Needle bar position is too high Refer to the standard adjustment figures...

Page 191: ...not use 2 D Needle thread guide rod D 1 Height is too low Correct the height to appropriate height 2 E Needle height E 1 Needle bar height is too low Refer to the standard adjustment figures 2 F Thre...

Page 192: ...d Do not use 3 D Needle thread guide rod D 1 Height is too low Correct the height to appropriate height 3 E Needle height E 1 Needle bar height is too low Refer to the standard adjustment figures 3 F...

Page 193: ...th the genuine part 4 B Needle B 1 Needle bend Replace the needle with the new one 4 C Needle height C 1 Needle bar position is too high Refer to the standard adjustment figures 4 D Threading D 1 Inco...

Page 194: ...1 Incorrect height protruding amount longitudinal position stroke and timing Refer to the standard adjustment figures 5 D Spreader thread guide D 1 Incorrect height and position Refer to the standard...

Page 195: ...1 Incorrect height protruding amount longitudinal position stroke and timing Refer to the standard adjustment figures 6 C Needle height C 1 Incorrect needle bar position Refer to the standard adjustme...

Page 196: ...he needle with the new one Use UY128GAS 7 C Spreader adjustment C 1 Incorrect height protruding amount position front and rear Refer to the standard adjustment figures 7 D Spreader thread guide D 1 In...

Page 197: ...orrectly 8 E Looper E 1 R of looper s ventral section is too large and ridge line is not tense for which needle thread is likely to slip from looper Replace it with the genuine part 8 F Looper adjustm...

Page 198: ...OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Trouble 1 Trouble 2 Cause 1 Cause 2 Check and corrective measures From the previous page...

Page 199: ...ading E 1 Incorrect threading Refer to threading diagram 9 F Needle thread tension F 1 Tension is too weak Increase tension 9 G Needle thread guide rod G 1 Substandard lower positioning of thread guid...

Page 200: ...nd incor rect polishing Replace the looper when modified or its is shape changed too much 11 D Needle height D 1 Needle bar position is too low Refer to the standard adjustment figures 11 E Threading...

Page 201: ...ch tongue of presser foot I 1 Thread threading is not smooth due to incorrect shape of stitch tongue Replace when modified or its shape is changed too much 5 13 Bulge 13 A Throat plate A 1 Stitch tong...

Page 202: ...read ten sion G 1 1st thread tension is too weak Increase tension 14 H Stitch tongue of presser foot H 1 Thread threading is not smooth due to incorrect shape of stitch tongue Replace when its shape i...

Page 203: ...ondensed Condensed voided letters Thickness 1 5 Thickness 0 5 Thickness 0 8 Thickness 1 5 A 4 3 4 drilled hole on the bottom surface depth 20 Drill a hole at the time of set up B 17 drilled hole C 2 3...

Page 204: ...5 1 303 333 R10 X X 86 5 109 4 68 2 R18 R 5 R 1 0 R 2 1 R 1 0 Z Z 432 192 1 21 272 1 21 23 46 R21 R5 R5 R21 R21 10 26 8 5 1 30 3 5 26 10 5 Y Y 3 locations Z Z 4 locations X X A 4 3 4 drilled hole on...

Page 205: ...10 390 15 40 75 R30 R30 R 3 0 R6 R30 R 6 50 5 0 Y Y A B C 5 x 20 4 x 8 5 D R10 E R 2 20 R2 R 2 10 R 2 R 2 26 8 5 1 30 R10 R10 R10 Y Y 3 locations A 4 3 4 drilled hole on the bottom surface depth 20 D...

Page 206: ...C F 163 74 5 97 4 56 2 R18 R 5 R 1 0 R 2 1 R 1 0 Z Z 192 1 21 372 1 21 23 46 R21 R5 R5 R21 R21 R21 R 1 0 R 1 0 3 5 26 10 5 Z Z 4 locations A 4 3 4 drilled hole on the bottom surface depth 20 Drill a...

Page 207: ...locations Z Z A 4 3 4 drilled hole on the bottom surface depth 20 Drill a hole at the time of set up B 17 drilled hole C 2 3 4 drilled hole on the bottom surface depth 10 Drill a hole at the time of s...

Page 208: ...A 4 3 4 drilled hole on the bottom surface depth 20 Drill a hole at the time of set up B 17 drilled hole C 2 3 4 drilled hole on the bottom surface depth 10 Drill a hole at the time of set up D Insta...

Page 209: ...Y 3 locations A 4 3 4 drilled hole on the bottom surface depth 20 Drill a hole at the time of set up B 17 drilled hole C 2 3 4 drilled hole on the bottom surface depth 10 Drill a hole at the time of...

Page 210: ...4 drilled hole on the bottom surface depth 20 Drill a hole at the time of set up B 17 drilled hole C 2 3 4 drilled hole on the bottom surface depth 10 Drill a hole at the time of set up D Installing p...

Page 211: ...ttom surface depth 20 Drill a hole at the time of set up B 17 drilled hole C 2 3 4 drilled hole on the bottom surface depth 10 Drill a hole at the time of set up D 7 3 8 drilled hole on the bottom sur...

Page 212: ...ole at the time of set up B 17 drilled hole C 2 3 8 drilled hole on the bottom surface depth 10 Drill a hole at the time of set up D 7 3 8 drilled hole on the bottom surface depth 10 Drill a hole at t...

Page 213: ...85 A B C D Z Z 4 locations A 4 3 4 drilled hole on the bottom surface depth 20 Drill a hole at the time of set up B 17 drilled hole C 2 3 4 drilled hole on the bottom surface depth 10 Drill a hole at...

Page 214: ...drilled hole C 2 3 4 drilled hole on the bottom surface depth 10 Drill a hole at the time of set up D Installing position of drawer stopper on the bottom surface E JUKI logo type F 4 10 5 drilled hol...

Page 215: ......

Page 216: ...206 8551 JAPAN PHONE 81 42 357 2371 FAX 81 42 357 2274 http www juki com An environmental management system to promote and conduct the following 1 Eco friendly development of products and technologie...

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JUKI MF-7900 Series, Engineer'S Manual

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