Page 1 High-speed, Cylinder-bed Top and Bottom Coverstitch Machine MF-7900 Series High-speed, Semi-dry-head, Cylinder-bed Top and Bottom Coverstitch Machine MF-7900D Series ENGINEER’S MANUAL 70002000 No. E406-01...
Page 2 PREFACE This Engineer’s Manual is written for the technical personnel who are responsible for the service and maintenance of the machine. The Instruction Manual for these machines intended for the maintenance personnel and operators at an apparel factory contains operating instruction in detail. And this manual describes “Standard Adjust- ment”, “Adjustment Procedures”, “Results of Improper Adjustment”, and other important information which are not covered in the Instruction Manual.
Page 3 TO ENSURE SAFE USE OF YOUR SEWING MACHINE Adjustment : It means replacement of parts, disassembly, and repair assembly. For the sewing machine, automatic machine and ancillary devices (hereinafter collectively referred to as "machine"), it is inevitable to conduct sewing work near moving parts of the machine. This means that there is always a possibility of unintentionally coming in contact with the moving parts.
Page 4 JUKI assumes no responsibility for damages or personal injury or death resulting from the use of the machine for any application other than the intended one.
Page 5 1. Be sure to use JUKI genuine table and table stand in order to prevent accident that can result in personal injury or death. If it is inevitable to use a table and table stand which are not JUKI genuine ones, select the table and table stand which are able to support the machine weight and reaction force during operation.
Page 6 7. If the machine cannot be normally operated after repair or adjustment, immediately stop operation and contact JUKI or the distributor in your area for repair in order to prevent accident that can result in per- sonal injury or death.
Page 7 5. Be sure to use JUKI genuine 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 the specified range, immediately stop the re- placement work and ask JUKI or distributor in your area for replacement of the parts.
Page 8 Replacement of parts 1. In prevention of accident caused by unfamiliarity with the machine or electrical-shock accident, be sure to ask an electrical technician of your company or JUKI or distributor in your area for replacement of electrical components. 2. When it is necessary to open the control box containing electrical parts, be sure to turn the power off and wait for five minutes or more before opening the cover in order to prevent accident caused by un- familiarity with the machine or electrical-shock accident.
Page 9 2. In prevention of accident caused by unfamiliarity with the machine or electrical-shock accident, be sure to ask an electrical technician of your company or JUKI or distributor in your area for disassembly/as- sembly of electrical components. 3. When it is necessary to open the control box containing electrical parts, be sure to turn the power off and wait for five minutes or more before opening the cover in order to prevent accident caused by unfa- miliarity with the machine or electrical-shock accident.
Page 10 Precautions to be taken so as to use the MF−7900 Series more safely 1. To prevent accidents caused by electric shock, never open the motor control box cov- er or touch the components inside the control box while the power switch is ON. DANGER 1.
Page 11 WARNING : To avoid malfunction and damage of the machine, confirm the following. • Be sure to fill the oil hole with oil designated by JUKI before use. • Clean the sewing machine thoroughly before using it for the first time.
Page 13: Table Of Contents
(20) How to change needle bar stroke ....................54 (21) How to change the spreader ....................... 58 (22) MF-7500 Series/MF-7900 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 .....................
Page 14 (6) Replacement procedure of the moving knife and the counter knife ........131 (7) Adjustment procedure of the cloth guide ................131 (8) Adjustment procedure of front-up amount of the presser foot ..........132 (9) Adjustment procedure of the position of the tape guide ............132 (10) Installing the accessories (tape guide base, tension roller and suction pipe) supplied with the machine ......................
Page 15: Specifications
16 Lubricating sys- Forced lubrication method by gear pump 17 Lubricating oil JUKI CORPORATION GENUINE OIL 18 (Equivalent to ISO VG18) 18 Oil reservoir Oil gauge lower line : 600 cc to upper line : 900 cc capacity 19 Installation...
Page 16: Configuration Of The Machine Components
2. Configuration of the machine components ❺ ❼ ❻ ❸ ❹ ❷ ❶ ❽ ❾ ❶ Presser spring regulator Throat plate ❷ Needle bar thread take-up cover Needle tip silicon oil lubricating unit ❸ Oil circulation inspection windows Differential lock nut ❹...
Page 17: Motor Pulley And Belt
When you use a new sewing machine, use the following sewing speed for the first 200 hours (approxi- mately one month). A good result can be obtained in terms of the durability. • MF-7900 Series : 4,500 sti/min or less • MF-7900D Series : 4,000 sti/min or less (Caution) 1.
Page 18: Standard Adjustment
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 ❷ ❶ ❹ ❸ ❶ ❷ Broken lines A when stretcher thread When covering thread is When covering thread is excessively is used...
Page 19 Adjustment procedures Results of Improper adjustment When motion of thread is very rough, and stable seams can ◦ When threading is not proper- not be obtained, there are cases where the condition can be ly performed, not only sewing improved by the following threading. trouble occurs, but also needle (1) Wind thread around 1st thread guide ❺...
Page 20: Adjusting The Rocking Thread Take-Up
(2) Adjusting the rocking thread take-up WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Length of the rocking thread take-up (1) It is the standard that the length of rocking thread take-up ❷ from the center of the shaft of rocking thread take-up support arm ❹...
Page 21 Adjustment procedures Results of Improper adjustment Length of the rocking thread take-up ◦ When length of rocking thread (1) Loosen screws ❶ and move rocking thread take-up ❷ to the take-up ❷ is lengthened, needle right or left to adjust the length. thread is tightened.
Page 22: Adjusting The Needle Thread Loop By The Eccentric Cam
(3) 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 ❷ ❶ – 8 –...
Page 23 Adjustment procedures Results of Improper adjustment Remove the top cover. Loosen screw ❶ . Turn the eccentric cam ❷ . The direction of turning the eccen- tric cam and the relation between the eccentric cam and the needle thread loop is shown in the following table. •...
Page 24: Adjusting The Position Of The Needle Thread Guide Rod
(4) Adjusting the position of the needle thread guide rod WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Position of the needle thread guide rod (1) It is the standard that the height of needle thread guide rods ❶...
Page 25 Adjustment procedures Results of Improper adjustment Loosen setscrews ❸ , adjust the height of respective needle ◦ When needle thread guide rod thread guide rods ❶ , and fix the rods with setscrews ❸ . ❶ is raised, needle thread is (Caution) 1.
Page 26: Adjusting The Position Of The Thread Receiver
(5) Adjusting the position of the thread receiver WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Position of the 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 ❶...
Page 27 Adjustment procedures Results of Improper adjustment Loosen setscrew ❸ and move needle bar thread take-up ◦ Since larger thread loops are thread receiver ❶ up or down to adjust the height. formed by raising needle bar thread take-up receiver ❶ , it is When desired to make needle bar thread take-up thread re- ceiver ❶...
Page 28: Adjusting The Position Of The Spreader Thread Guide And Spreader Thread Take-Up
(6) Adjusting the position of the spreader thread guide and spreader thread take-up WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Relation of the position between spreader thread take-up ❶ and spreader thread guide ❷ is the stan- dard when the top end of thread hole C of spreader thread guide ❷...
Page 29 Adjustment procedures Results of Improper adjustment Loosen setscrews ❹ in spreader thread guide ❷ and adjust ◦ When the relation of position the position of spreader thread guide ❷ . (Spreader thread between spreader thread take- take-up ❶ is fixed to rocking thread take-up ❺ and can not be up ❶...
Page 30: Adjusting The Spreader
(7) Adjusting the spreader WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Height of the spreader It is the standard that the height from the top surface of throat plate ❷ to the bottom surface of spreader ❶...
Page 31 Adjustment procedures Results of Improper adjustment Adjusting the height of the spreader ◦ Height of the spreader is improp- Adjusting the longitudinal position of the spreader er, stitch skipping of spreader Loosen setscrew ❸ and adjust the height and longitudinal posi- occurs.
Page 32 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Adjustment figures of the spreader thread guide (1) It is the standard that the clearance provided between spreader ❶ and spreader thread guide is 0.4 to 1.0 mm.
Page 33 Adjustment procedures Results of Improper adjustment Spreader thread guide ◦ When height or position of the (1) Adjust the height of spreader ❶ to 7.8 to 8.2 mm. Loosen spreader thread guide is im- setscrews in the spreader thread guide and adjust the proper, stitch skipping of spread- clearance provided between the top surface of spreader ❶...
Page 34: Adjusting The Timing Relation Between The Looper And Needle Bar
(8) Adjusting the timing relation between the looper and needle bar WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Timing relation between the looper and the needle bar (synchronization) It is the standard that dimension 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 point of looper, and when the needle bar comes down from the upper dead...
Page 35 Adjustment procedures Results of Improper adjustment To adjust the timing relation between the needle and the looper, ◦ When the difference in timing remove the top cover, loosen four setscrews ❶ in the sprocket (going and returning) of looper is and turn upper pulley ❷...
Page 36: Returning Amount Of The Looper
(9) Returning amount of the looper WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment It is the standard that returning amount of looper ❶ from top end of looper ❶ to the center of needle bar is 5.9 mm regardless of the needle gauge when looper ❶...
Page 37 Adjustment procedures Results of Improper adjustment Loosen setscrew ❷ in the looper holder and move looper hold- ◦ When the returning amount is er ❸ to the right and left for adjust. large, loop of needle thread becomes large and it is apt to After the adjustment, tighten setscrew ❷...
Page 38: Height Of The Needle
(10) Height of the needle WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment It is the standard that the top end of needle eyelet of left needle aligns with the bottom end of looper when the top end of looper passes the rear of the needle from the extreme right position and protrudes from the left end of left needle by...
Page 39 Adjustment procedures Results of Improper adjustment Remove rubber cap ❷ in the face plate, loosen setscrew ❸ in ◦ When the height of the needle is the needle bar bracket and adjust the height of the needle bar. excessively different, stitch skip- After adjusting the height, equally adjust the clearance A be- ping, needle breakage, thread tween needle ❶...
Page 40: Locus And Longitudinal Motion Of The Looper
(11) Locus and longitudinal motion of the looper WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment It is the standard that the top end of left needle touches the position of 1/4 to 1/3 from the bottom face of the back of the looper when the looper returns from the extreme left position in...
Page 41 Adjustment procedures Results of Improper adjustment Changing the longitudinal motion of the looper ◦ When the longitudinal motion of (1) Remove 10 setscrews ❶ in bed top cover and remove the cov- the looper is small, the rate that needle touches the back of the * The position where engraved marker line E on looper driving looper is increased and blunt arm ❷...
Page 42: Adjusting The Needle Guard
(12) Adjusting the needle guard WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Standard position of the rear needle guard ❹ (1) Lateral position of rear needle guard ❶...
Page 43 Adjustment procedures Results of Improper adjustment Remove setscrews ❷ and remove needle cooler unit ❸ and cam cover ❾ . Adjust the height of rear needle guard ❶ with setscrew ❺ and ◦ When the clearance provided between rear needle guard ❶ adjust the longitudinal position with setscrew ❼...
Page 44 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Standard position of the 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 ❶...
Page 45 Adjustment procedures Results of Improper adjustment Height of the front needle guard ◦ When the clearance provided (1) Adjust the height of front needle guard to the position where between front needle guard it is higher by 3.3 ± 0.5 mm than rear needle guard ❶ with set- and the needle is larger, loop screw .
Page 46: Adjusting The Feed Dog
(13) Adjusting the feed dog WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Height of the feed dog It is the standard that the height of feed dogs (main feed dog ❷ and differential feed dog ❹ ) is 1 ± 0.1 mm from the top surface of the throat plate ❶...
Page 47 Adjustment procedures Results of Improper adjustment Adjusting the height of the feed dog ◦ When the position of the feed (1) Loosen setscrew ❼ in the differential feed dog and setscrew ❸ dog is high, stitch skipping, de- in the main feed dog, and adjust the height. fective chain-off, return of feed, (2) Adjust the top surface of throat plate ❶...
Page 48 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment 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 of the feed dog in terms of the slots of the throat plate are parallel and equal.
Page 49 Adjustment procedures Results of Improper adjustment Adjusting the lateral position of the feed dog ◦ When the lateral position of the (1) Loosen setscrew ❷ in rocking bar presser, right ❶ , and loosen rocking bars ❺ and ❻ is incor- setscrews ❹...
Page 50 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Longitudinal position of the feed dog (1) Position of the main feed dog : it is the standard that the position where the clearance from the edge of the slot of the throat plate to the front face of the main feed dog is 0.6 ±...
Page 51 Adjustment procedures Results of Improper adjustment Longitudinal position of the feed dog (condition : feed momen- ◦ When the fixing position of the tum 3.6 mm (maximum)) main feed lever slips greatly out (1) Remove the bed top cover. of position, abnormal noise or (2) Adjusting the longitudinal position of the main feed dog abrasion will be caused.
Page 52: Adjusting The Feed Relation
(14) Adjusting the feed relation WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Changing the stitch length It is possible for the standard stitch length to adjust up to 0.9 to 3.6 mm. Turning feed adjust knob ❶...
Page 53 Adjustment procedures Results of Improper adjustment Changing the stitch length ◦ When the stitch length is set to (1) When making the stitch length more than 3.6 mm, loosen set- more than 3.6 mm, the contact screw ❷ of the feed adjustment stopper pin, turn feed adjust of main feed dog, differential knob ❶...
Page 54 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Adjusting the feed locus (1) Changing the feed driving motion The timing of feed driving eccentric cam ❶ of the feed mechanism can be retarded from the timing obtained by the standard adjustment.
Page 55 Adjustment procedures Results of Improper adjustment (1) Changing the feed driving motion Loosen two setscrews of the feed driving eccentric cam ❶ . Carry out the adjustment when the hole A in the feed driving rod ❷ aligns with the setscrew of the feed driving eccentric cam ❶...
Page 56: Adjusting The Presser Foot
(15) Adjusting the presser foot WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Height of the presser foot Height of the presser foot has to be the position the presser foot does not come in contact with other components at the position where lifter lever ❶...
Page 57 Adjustment procedures Results of Improper adjustment Adjusting the height of the presser foot ◦ When the position of the press- Loosen adjustment nut ❷ . Lower lifter lever ❶ , adjust height er foot is too high, it comes in adjustment screw ❸...
Page 58: Adjusting The Micro-Lifter
(16) Adjusting the micro-lifter WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Micro-lifter Adjust the micro-lifter in accordance with sewing conditions for use. Major applicable process (1) When twist occurs in the hemming bottom process.
Page 59 Adjustment procedures Results of Improper adjustment When the micro-lifter collar ❶ is turned clockwise 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.
Page 60: Adjusting The Looper Thread Cam
(17) Adjusting the looper thread 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 Adjust so that thread comes off from the highest place of looper thread cam ❷ when needles come down and the top end of left needle ❸...
Page 61 Adjustment procedures Results of Improper adjustment Loosen setscrews ❶ in the looper thread cam ❷ and adjust ◦ When the position of looper thread cam ❷ slips greatly out of while checking that looper thread comes off from the periphery of the looper thread cam ❷...
Page 62: Adjustment Value Of Balloon
(18) Adjustment 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 ② Thread ❸ ❷ ❹ ❶ ③ ④ 29 mm 17 mm Lower by 6 mm ⑤...
Page 63 Adjustment procedures Results of Improper adjustment When performing balloon stitch, carry out the adjustment referring to the adjustment values de- scribed below. (Caution) Balloon stitches may not be formed smoothly according to the type of thread and fabric. [2-needle balloon stitch without top covering] ①...
Page 64: With Regard To Lubrication
Lubricating oil has been taken out at the time of delivery. Be sure to supply lubricating oil before using 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.
Page 65 Adjustment procedures Results of Improper adjustment Inspection and replacement ◦ In case oil cannot be observed Loosen setscrews ❸ in the oil filter cap and remove oil filter from oil circulation identifica- cap ❷ . tion window ❹ even when the Draw out oil filter ❶...
Page 66 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Oiling (MF-7900D only) No oiling Replacing the lubricating oil ❶ – 52 –...
Page 67 Replacing the lubricating oil In case of the new sewing machine, replace the lubricating oil (JUKI CORPORATION GENUINE OIL 18) with new one after using it for approximately one month. Then replace the lubricating oil every six months.
Page 68: How To Change Needle Bar Stroke
(20) How to change needle bar stroke WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment 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 ❺...
Page 69 Adjustment procedures Results of Improper adjustment Changing the needle bar stroke ◦ In case of the thick materials, (1) Loosen setscrew ❻ (remove the rubber plug) in eccentric pin the stroke is changed. However, ❺ . basically, use the machine with (2) Draw out eccentric pin ❺...
Page 70 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Adjusting the height of the needle bar When the needle bar stroke is changed, be sure to adjust the height of the needle bar. 1) Adjust clearances C provided between needles ❽...
Page 71 Adjustment procedures Results of Improper adjustment Adjusting the height of the needle bar ◦ When the position of the height (1) Loosen setscrew ❾ in the needle bar bracket and adjust the of the needle bar is excessively height of the needle bar. different, stitch skipping, needle (2) After adjusting the height of the needle bar, adjust clearances breakage, thread breakage, etc.
Page 72: How To Change The Spreader
(21) How to change the spreader WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment Changing the spreader When the needle bar stroke is changed, be sure to perform to adjusting the height of the spreader ❶ of "4.-(7) Adjusting the spreader".
Page 73 Adjustment procedures Results of Improper adjustment Refer to "4.-(7) Adjusting the spreader". – 59 –...
Page 74: Mf-7500 Series/Mf-7900 Series How To Use The Timing Gauge
Needle gauge Left needle height MF-7500 Series and MF-7900 Series are different in the height. 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". Height of the needle bar varies in accordance with the needle gauges.
Page 75 Insert the timing gauge between the top surface of the throat plate and the bottom surface of the spreader. MF-7500 Series and MF-7900 Series are different in the height. Use the gauge on which MF-7500 Series is stamped for "MF-7700"...
Page 76: Ut51, 52 (Solenoid Type Thread Trimmer)
5. UT51, 52 (Solenoid type thread trimmer) (1) Installing the SC-921 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. 1) Wiring ❹ ❾ CN37 CN42 ❸...
Page 77: Adjusting And Setting Sc-921
(2) Adjusting and setting SC-921 When SC-921 is used, refer to the instruction manual of SC-921, and assemble the product. Setting procedure of the machine head (Caution) For the operation panel other than CP-18, refer to the Instruction Manual for the operation panel to be used for the setting procedure of the machine head.
Page 78 3) Machine head list Contents Sewing speed at the Max. sewing speed No. SC-920 SC-921 Machine head Type of display delivery (sti/min) (sti/min) ○ ○ DDL-9000B MA/MS/SS dLbM 4000 5000 ○ ○ DDL-9000B DS dLbd 4000 4000 ○ ○ DDL-9000B SH dLbH 4000 4500...
Page 79 4) Adjusting the machine head (direct-drive motor type sewing machine only) (Caution) When the slip between the marker line F on the hand-wheel and the concave E of the ma- chine head is excessive after thread trimming, adjust the angle of the machine head by the operation below.
Page 80 After the adjustment above has been per- formed, when the sewing machine stops at the DOWN position, top end C of the looper is lo- cated at the position where it has scooped loop D of left needle thread as shown in the figure. (Caution) 1.
Page 81 5) Setting 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 function makes the function of auto-lifter work. ❶...
Page 82: Adjusting The Looper Thread Trimmer Mechanism
(3) Adjusting the looper thread trimmer 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 rest. Standard adjustment 1.
Page 83 Adjustment procedures Results of Improper adjustment 1. Adjusting the looper thread trimmer solenoid (1) Stroke of looper thread trimmer solenoid ❸ is 17.5 ± 0.5 mm. (2) When adjusting the stroke, loosen setscrew ❷ of collar ❶ and move collar ❶ to the right or left to adjust. (3) After adjusting the stroke, loosen screw from the lower side, and move collar to the left and right to adjust so that the distance between rubber cushion and UT base is 18 mm.
Page 84 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. 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 the knife engagement and the knife pressure adjusting spring...
Page 85 Adjustment procedures Results of Improper adjustment (1) Adjusting the Lower knife Set lower knife ❹ and lower knife holder ❺ with setscrews ❻ at the position of the illustration. (2) Adjusting the position of clamp pressure adjusting spring Loosen screws ❾ . Adjust so that a clearance of 2.5 ±...
Page 86 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. Standard adjustment (5) Initial position of the looper thread trimmer mechanism (6) Adjusting the stopper (7) Adjusting the height of the lower knife ❹...
Page 87 Adjustment procedures Results of Improper adjustment (5) Initial position of the lower thread trimmer mechanism When the lower knife ❹ is located at its leftmost position, the top end of the lower knife ❹ has to be spaced 24 ± 0.5 mm from the center of needle bar.
Page 88 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. Standard adjustment (9) Adjusting the longitudinal position of the blade point of lower knife Blade point of lower knife ❹...
Page 89 Adjustment procedures Results of Improper adjustment (9) Adjusting the longitudinal position of the blade point of low- er knife 1. Bring the needle bar to its highest position. 2. Adjust so that the blade point of lower knife ❹ is in the center of the thickness of looper when the clearance between the right-hand edge of looper and the blade point of lower knife ❹...
Page 90 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. Standard adjustment (10) Adjusting the thread trimmer sensor –...
Page 91 Adjustment procedures Results of Improper adjustment (10) Adjusting the thread trimmer sensor The safety switch is installed so that the sewing machine does not start unless the looper thread trimmer device returns to its home position. 1. Loosen setscrews . 2.
Page 92 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. Standard adjustment (11) Adjusting the disk-rise (12) Adjusting the thread release hook Clearance between click B and disk ❹...
Page 93 Adjustment procedures Results of Improper adjustment (11) Adjusting the disk-rise 1. Loosen setscrew ❷ in adjustment cam ❶ , turn adjustment cam ❶ and disk-rise plate ❸ moves up or down. 2. Adjust the clearance between the click section B of disk-rise plate ❸...
Page 94: Adjusting The Top Covering Thread Trimmer Mechanism
(4) Adjusting the top covering thread trimmer 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 rest. Standard adjustment ❹...
Page 95 Adjustment procedures Results of Improper adjustment 1. Adjusting the engagement of knives (1) Adjust so that the engagement of fixed knife ❶ with moving knife ❷ is 0.5 mm. (2) When adjusting the engagement, loosen setscrews ❹ and move knife holder ❺ up or down to adjust. 2.
Page 96: Adjusting The Needle Stop Position At Thread Trimming
(5) Adjusting the needle stop position at thread trimming 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. Standard adjustment 1.
Page 97 Adjustment procedures Results of Improper adjustment 1. DOWN position (1) DOWN position of the needle is the position where top end B of the looper has scooped loop A of the left needle thread. If it is incorrect, adjust the down position of the needle by func- tion setting No.122 (DOWN position starting angle compensa- tion) of SC-921.
Page 98: Ut55, 56, 57 (Pneumatic Type Thread Trimmer)
6. UT55, 56, 57 (Pneumatic type thread trimmer) (1) Installing the SC-921 • Compressed air/Air consumption Top and bottom Bottom thread trimmer Air-blow MC37 Air consumption Compressed air thread trimmer Auto-lifter type wiper MC40 /min (ANR) Auto-lifter ○ UT55 ○ ○...
Page 99 2. Connecting the cords Pass cords ❶ of the thread trimming solenoid, reverse-stitching solenoid, etc. and the cord from the motor through hole A in the table to route them down under the machine table. ❶ Loosen screw B in cover ❷ with a screwdriver to open the cover ❷...
Page 100: Piping Of The Thread Trimmer Device
(2) Piping of the thread trimmer device 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. In addition, cut the air supply from air compressor.
Page 101 Adjustment procedures Results of Improper adjustment Adjusting the air regulator ❷ Air hose ❶ ❸ (1) Insert the air hose to air regulator ❶ . (2) Use the air pressure at 0.5 MPa (5 kgf/cm (3) Draw up regulator knob ❷ , turn knob ❷ and adjust the pointer to 0.5 MPa to adjust the air pressure.
Page 102: Adjusting The Looper Thread Trimmer Mechanism
(3) Adjusting the looper thread trimmer mechanism WARNING : As the work is performed 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.
Page 103 Adjustment procedures Results of Improper adjustment 1. Adjusting the thread trimmer air cylinder (1) Stroke of air cylinder ❸ is 18 mm. When adjusting the stroke, loosen setscrew ❷ of collar ❶ and move collar ❶ to the right or left to adjust. 2.
Page 104: Adjusting The Top Covering Thread Trimmer Mechanism
(4) Adjusting the top covering thread trimmer 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 rest. In addition, cut the air supply from air compressor.
Page 105 Adjustment procedures Results of Improper adjustment 1. Adjusting the engagement of knives (1) Adjust so that the engagement of fixed knife ❶ with moving knife ❷ is 0.5 mm. (2) When adjusting the engagement, loosen setscrews ❹ and move knife holder ❺ up or down to adjust. 2.
Page 106: Adjusting The Air-Blow Wiper (Ut56)
(5) Adjusting the air-blow wiper (UT56) WARNING : As the work is performed 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.
Page 107 Adjustment procedures Results of Improper adjustment 1. Installing the air-blow wiper (1) When using air-blow wiper ❶ , remove the top covering thread trimmer device. (2) Tighten air-blow wiper ❶ with setscrews ❷ . (3) Perform piping referring to "6.-(2) Piping of the thread trimmer device".
Page 108: Adjusting The Needle Thread Wiper (Ut55)
(6) Adjusting the needle thread wiper (UT55) 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. In addition, cut the air supply from air compressor.
Page 109 Adjustment procedures Results of Improper adjustment 1. Adjusting the clamp spring Adjust the leaf spring which clamps the needle thread after the wip- er operates. (1) Install clamp spring ❽ on wiper ❺ with screw ❾ so that they are in parallel to each other. (2) Fix clamp spring with the screw so that the top end of clamp spring ❽...
Page 110: Adjusting The Needle Stop Position At Thread Trimming
(7) Adjusting the needle stop position at thread trimming 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. Standard adjustment 1.
Page 111 Adjustment procedures Results of Improper adjustment 1. DOWN position (1) DOWN position of the needle is the position where top end B of the looper has scooped loop A of the left needle thread. If it is incorrect, adjust the down position of the needle by func- tion setting No.122 (DOWN position starting angle compensa- tion) of SC-921.
Page 112 – 98 –...
Page 113: H22, 23 (Hemming Type (With Left Hand Fabric Trimmer))
7. H22, 23 (Hemming type (with left hand fabric trimmer)) (1) Specifications Model MF-7900-H22 MF-7900-H23 Class name Covering stitch machine with left hand fabric Covering stitch machine with left hand fabric trimmer (for light-weight materials) trimmer (for medium-weight materials) Application Hemming of knit and jersey products Sewing speed Max.
Page 114: Adjustment
(2) Adjustment 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 upper knife pressure ❶ ❷ ❸ ❹ ❺ ❻ 2. Adjusting the lateral position of the lower knife ❾...
Page 115 Adjustment procedures Results of Improper adjustment 1. Adjusting the upper knife pressure Standard adjustment position of thrust collars ❶ and ❷ is such that a clearance of 10 mm is provided between them. Place thrust collar ❶ between spring ❺ and bushing ❸ . Press thrust collar ❶...
Page 116 WARNING : Turn OFF the power 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 ❶ 0.5 mm ❷ ❸ 4. Replacement procedure of upper knife and lower knife ❼...
Page 117 Adjustment procedures Results of Improper adjustment 3. Adjustment procedure of engagement amount of knives (1) Loosen setscrew ❸ in the upper knife holder and adjust so that the engagement amount of the top end of the upper knife ❶ and lower knife ❷ is approximately 0.5 mm when upper knife ❶...
Page 118 WARNING : 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 upper knife stroke ❹ ❸ ❷ ❶ ❼ ❺ ❻ D : Standard adjustment angle 6.
Page 119 Adjustment procedures Results of Improper adjustment 5. Adjusting the upper knife stroke (1) Loosen setscrews ❶ in the waste cloth pipe and remove waste cloth pipe ❷ . (2) Remove setscrews ❸ in the installing base cover, and remove installing base cover ❹ . (3) Loosen lock nut ❺...
Page 120 – 106 –...
Page 121: Mc37, Mc40 (Pneumatic Cloth Chip Suction Device)
8. MC37, MC40 (Pneumatic cloth chip suction device) MC37 MC40 (1) Specifications and features Model MC37 MC40 Name Pneumatic cloth chip suction device with a Pneumatic cloth chip suction device with a solenoid valve pedal connecting rod air switch Applicable machines MF-7900-H22, 23 and MF-7900-E11 pro- MF-7900-H22, 23 and MF-7900-E11 vided with the control box (SC-921) Major features...
Page 122: Installation And Adjustment
(2) Installation and adjustment 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. Installing the connecting rod MC40 ❶ ❸ ❷ 2. Adjusting the connecting rod air valve MC40 ❹...
Page 123 Adjustment procedures Results of Improper adjustment 1. Installing the connecting rod MC40 (1) Taking care of the vertical direction of the connecting rod, fix the top end of the rod on motor lever A using the screw of ball joint ❶ , and fix the bottom end of the rod on pedal lever B using the screw of ball joint ❷...
Page 124 WARNING : Turn OFF the power before starting the work so 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 Rear of the frame ❶ 550 mm ❻...
Page 125 Adjustment procedures Results of Improper adjustment 3. Assembling the cloth chip and chain-off thread suction device (1) Fix two tube clips ❶ to mounting plate ❹ with screws ❷ and fitting lock nuts ❸ . (2) Fix mounting plate ❹ with (tube clip) installing wood screws ❺ so that tube clips ❶...
Page 126 WARNING : 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 suction force 6. Installing the waste bag ❷ ❻ Stand Stand 30 mm ❶...
Page 127 Adjustment procedures Results of Improper adjustment 5. Adjusting the suction force (1) When A is turned clockwise, the suction force is decreased. (2) For the mechanical valve of MC37, the suction force can be adjusted by turning B with a screwdriver or the like. 6.
Page 128 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine. Standard adjustment 7. Piping the air components Piping diagram for the MC37 MF-7900-E11 MF-7900-H22,23 ❶ ➡ Piping diagram for the MC40 MF-7900-E11 MF-7900-H22,23 ➡...
Page 129 Adjustment procedures Results of Improper adjustment 7. Piping the air components (1) Fix solenoid valve ❶ 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 too long. Cut it to an appropri- ate length before connecting it.
Page 130 WARNING : 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 SC-921) ❷ ❶ ❸ ❹ Fig.
Page 131 Adjustment procedures Results of Improper adjustment 8. Installing procedure of the exclusive cord for MF (Installing SC-921) Connect the exclusive cords for MF to the respective specified con- nectors. • Thread trimmer sensor cord ❶ → CN42 • Presser lifter cord ❷ → CN37 •...
Page 132 – 118 –...
Page 133: Pl12, 13 (Cloth Puller)
9. PL12, 13 (Cloth puller) PL12 PL13 (1) Specifications Model PL12 (Gear roller) , PL13 (Flat roller) Class name Cloth puller device Sewing speed Max. 5,000 sti/min (at the time of intermittent operation) Speed of stitch at the delivery. 4,000 sti/min (at the time of intermittent operation) Lift of roller Manual lever PL12 : 8.6 mm , PL13 : 10.3 mm Presser lifter When lift of presser foot is 4 mm PL12 : 6.3 mm, PL13 : 8.0 mm...
Page 134: Installation And Adjustment
(2) Installation and adjustment 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 ❷ ❶ 2. Adjusting the feed amount of the roller ❻...
Page 135 Adjustment procedures Results of Improper adjustment 1. Adjusting the roller presser pressure (1) Loosen nut ❶ , and turn presser spring regulator ❷ to the right (clockwise) when increasing the presser pressure. (2) Turn presser spring regulator ❷ to the left (counterclockwise) when decreasing the presser pressure.
Page 136 WARNING : 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 ❷ 0.5 mm ❸ ❶ 4. Assembling the rear roller asm. ❺...
Page 137 Adjustment procedures Results of Improper adjustment 3. Adjusting the roller presser lifter (1) Adjust with two screws ❶ so that the clearance between press- er lifter lever link, short ❷ and hinge screw ❸ is 0.5 mm when performing the presser lifting in the state that the top roller is lowered.
Page 138 WARNING : 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 ❸ ❷ ❶ 6. Grease lubrication system – 124 –...
Page 139 Adjustment procedures Results of Improper adjustment 5. Adjusting the clutch tension spring (1) Adjustment is performed with clutch tension spring ❶ so that the top roller does not overrun at high-speed rotation. (2) When performing the adjustment, loosen cap nut ❷ , and turn nut ❸...
Page 140 WARNING : Turn OFF the 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 ❶ ❷ ❸ 8. Adjusting the clearance between the gear rollers (PL12) 0.3 mm ❹...
Page 141 Adjustment procedures Results of Improper adjustment 7. Feed timing of the roller (1) Notch A in collar ❸ aligns with notch B in the puller eccentric cam ❶ when the roller is placed in the standard position. When changing the feed timing, loosen two setscrews ❷ in puller eccentric cam ❶...
Page 142: Mf-7900-E11
10. MF-7900-E11 (1) Specifications Model MF-7900-E11 Class name Right-hand fabric undertrimmer for pre-closed elastic attaching with tension roller Pre-closed waist elastic attaching of men's brief, trunks, etc. Application (Waist elastic width up to 40 mm) Max. 5,000 sti/min (provided with PL12 or PL13) (at the time of intermittent operation) Sewing speed Speed of stitch at the delivery.
Page 143: Adjustment Procedure Of The Knife Pressure
(3) Adjustment procedure of the knife pressure 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. Make the engagement pressure of moving knife and counter knife as low as possible within the range of smooth cutting of fabric.
Page 144: Adjusting The Engagement Angle Of The Knife
(5) Adjusting the engagement angle of the knife 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. Loosen setscrew ❶...
Page 145: Replacement Procedure Of The Moving Knife And The Counter Knife
(6) Replacement procedure of the moving knife and the counter knife 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. Remove setscrew ❸...
Page 146: Adjustment Procedure Of Front-Up Amount Of The Presser Foot
(8) Adjustment procedure of front-up amount of the presser foot 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. When sewing a thick rubber sheet or the like togeth- er, fabric can be smoothly fed by raising the front of presser foot ❶...
Page 147: Installing The Accessories (Tape Guide Base, Tension Roller And Suction Pipe) Supplied With The Machine
(10) Installing the accessories (tape guide base, tension roller and suction pipe) supplied with the machine 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. 1.
Page 148 4. Installing the rear roller (1) Fix rear roller plate base ❶ with three wood ❻ ❸ ❹ ❺ screws ❷ . ❷ (Reference) For the installing position of the rear roller plate base ❶ , refer to the drawing of the table. (2) Install rear roller (asm.) ❸...
Page 149: Adjusting Procedure Of The Position Of The Tension Roller
(11) Adjusting procedure of the position of the tension roller 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. 1.
Page 150 3. Adjusting the position of the bottom roller ❶ (1) Adjusting the lateral position Loosen three screws ❶ , adjust the bottom roll- ❸ er ❸ so that the elastic belt is put straight, and tighten three screws ❶ . (2) Adjusting the vertical position Loosen clamp lever ❷...
Page 151: Adjusting Procedure Of The Position Of The Tape Guide Base
(12) Adjusting procedure of the position of the tape guide base 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. 1.
Page 152 2. Adjusting the elastic guide (1) Adjusting the lateral position ❶ Loosen screw ❶ , adjust presser guide ❷ to the right-hand side of the elastic belt, and tighten screw ❶ . ❸ ❷ (2) Adjusting the angle and length Loosen screw ❸...
Page 153 3. Adjusting the elastic belt presser plate (1) Adjusting the lateral position Loosen screw ❶ and screw ❷ , and adjust presser bar ❺ so that the clearance between ❻ cloth presser ❸ and knife ❹ is 0.5 mm. Then tighten screw ❶...
Page 154 (3) Adjusting the position of lever ❷ Loosen screw ❶ , and adjust so that the clear- ❸ ❷ ance between lever ❷ and the top surface of presser ❸ is 3 mm. Then tighten screw ❶ . ❶ ❷ ❸...
Page 155: How To Use The Knife Cancelling Mechanism
(13) How to use the knife cancelling 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 rest. Depress lever ❶...
Page 156: Mf-7900-E22/23
11. MF-7900-E22/23 (1) Specifications Model MF-7900-E22, MF-7900-E23 Model name E22 : Machine for attaching endless spandex elastic tape (With manual open/ close type binder) E23 : Machine for attaching endless spandex elastic tape (With pneumatic open/close type binder) Sewing speed Max.
Page 157 After the installation of the open/close device ❸ , ❺ apply grease supplied with the device to section * Exclusive grease (Unirex N2) JUKI part No. : 13525506 Installing the lever (asm.) Install lever (asm.) ❻ with setscrew ❾ (slotted head screw, black, screw shank length 14 mm).
Page 158 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. Installing the chain and pulley Install the chain ❾...
Page 159: Adjustment Procedure
2) Adjustment procedure 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. Adjusting the position of the binder Perform the adjustment of the position of binder with screws .
Page 160: In Case Of Using E23
(3) In case of using E23 1) Installing procedure 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. Installing the binder open/close knee switch (asm.).
Page 161 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. Installing the binder and the elastic guide Install binder ❾...
Page 162: Adjustment Procedure
2) Adjustment procedure WARNING : As the work is performed 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. Adjusting the position of the binder Perform the adjustment of the position of binder ❾...
Page 163: With Regard To The Accessories (Tension Roller)
(4) With regard to the accessories (tension roller) 1) Installing procedure 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. Installing the bottom roller of the tension roller Install bottom roller plate ❶...
Page 164: Adjustment Procedure
Installing the rear roller (1) Fix rear roller plate base ❶ with three wood ❻ screws ❷ . ❸ ❹ ❺ ❷ (Reference) For the installing position of the rear roller plate base ❶ , refer to the drawing of the table. (2) Install rear roller (asm.) ❸...
Page 165 Adjusting the longitudinal position (1) Loosen knobs ❷ of slide shaft ❶ , and ad- just the longitudinal position. ❶ (2) After adjusting the position, tighten knobs ❷ . ❷ Adjusting the position of the bottom roller (1) Adjusting the lateral position Loosen three screws ❶...
Page 166: Mf-7900/Ut59
Spherical rod drive method Lubricating system Forced lubrication method by gear pump Lubricating oil JUKI CORPORATION GENUINE OIL 18 Oil reservoir capacity Oil gauge lower line : 600 cc to upper line : 900 cc Installation Table-mount type, Semi-submerged type...
Page 167: Installing The Accessories
(3) Installing the accessories 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. 1) Installing the air regulator Install air regulator (asm.) ❶...
Page 168: Connecting The Cords
3) Connecting the cords ❷ Loosen screw B in cover ❷ with a screwdriver ❶ to open the cover ❷ . Pass cords ❶ and of the thread-trimming solenoid, reverse feed stitching, motor signal etc. and the motor cord through the hole A in the table to route them to the underside of the table.
Page 169: Setting Procedure Of The Machine Head
4) Setting procedure of the machine head (Caution) For the operation panel other than CP-18, refer to the Instruction Manual for the operation panel to be used for the setting procedure of the machine head. Call function setting No. 95. ❶...
Page 170: Air Piping Drawing
(4) Air piping drawing 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. In addition, cut the air supply from air compressor.
Page 171: Threading The Machine Head
(5) Threading the machine head 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. If threading is wrong, stitch skipping, thread breakage, needle breakage or irregular stitches will be caused.
Page 172: Adjusting The Looper Thread Trimmer Mechanism
(6) Adjusting the looper thread trimmer 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 rest. In addition, cut the air supply from air compressor.
Page 173: Initial Position Of The Looper Thread Trimmer Mechanism
3) Initial position of the looper thread trimmer mechanism When the lower knife ❶ is locat- ❶ ed at its leftmost position, the top end of the lower knife ❶ has to be spaced 24 ± 0.5 mm from the center of needle bar.
Page 174: Longitudinal Position Of The Blade Point Of Lower Knife
4) Longitudinal position of the blade point of lower knife Bring the needle bar to its highest ❶ ❷ position. Adjust so that the clearance be- 0.4 ± 0.2 mm tween the blade point of lower knife ❶ and the front end face in the thickness direction of the looper ❷...
Page 175: Adjusting The Stopper
6) Adjusting the stopper Adjust the position of stopper ❸ ❷ so that a clearance of 0.3 to 1 mm is provided between looper ❶ and clamp pressure adjusting spring ❷ when the upper knife is located at ❶ its leftmost position (forward end). 0.3 to 1 mm ❸...
Page 176: Adjusting The Thread Trimmer Sensor
7) Adjusting the thread trimmer sensor The safety switch is installed so that the sewing ma- chine does not start unless the looper thread trimmer ❸ device returns to its home position. Loosen setscrews ❶ . ❷ Adjust switch plate ❷ so that LED of thread trimmer sensor ❸...
Page 177: Ss Lever Unit
(7) SS lever unit 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. 1) Installing the SS lever unit ❸...
Page 178: Setting The Upper Stop Position Of The Needle Bar
(8) Setting the upper stop position of the needle bar Ⓐ Simultaneously pressing switch ❹ and switch ❺ , turn ON the power switch. is displayed ( Ⓐ ) in the indi- cator and the mode is changed over to the adjustment mode. ❸...
Page 179 Remaining in the needle-bar upper stop position setting mode, turn the hand pulley of the machine head When the needle moves in by hand to lower the needle ❼ until the descending direction. the position where its tip is aligned with the center of the looper ❽...
Page 180: Setting The Raveling Prevention Parameter
(9) Setting the raveling prevention parameter Ⓐ Ⓑ ❶ Turn ON the power with Ⓒ switch ❼ held pressed. (The item which has been changed Ⓓ during the previous work is dis- played.) * If the screen display does not change, re-carry out operation de- scribed in step 1.
Page 181: Adjusting The Thread Hook
(10) Adjusting the thread hook WARNING : As the work is performed 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. ❷ ❶ ❸ When the needle moves in the descending direction.
Page 182 ❷ ❶ ❸ 1 to 1.5 mm (Clearance) ❹ ❺ ❻ Loosen setscrews ❶ which are temporarily tightened. Adjust the projecting position of thread hook ❻ . (Caution) Switch ❸ of the solenoid valve remains in the ON state. Sliding the air cylinder base (general asm.) ❷ in the direction A, the thread hanging hook ❻ moves to the direction C, sliding it in the direction B, the thread hook ❻...
Page 183 ❼ ❸ ❾ 6 to 7 mm (Clearance) ❹ Standby position ❺ ❻ ❻ Adjust the holding position of the thread hook ❻ . Release the switch ❸ of solenoid valve. 10. Temporarily tighten setscrews ❼ . 11. If setscrews ❼ moves to the direction A, the thread hook ❻ moves to the direction C, and if it moves to the direction B, the thread hook ❻...
Page 184: Other Cautions
(2) Application of appropriate grease Where lubrication is needed in any parts other than the lubricating sections, the appropriate grease (JUKI Grease A; 23640204, JUKI Grease B; 40013640) is already applied. Never use any other type of grease. 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) of the appropriate grease may be effective.
Page 185 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 JUKI Grease B. 3. There is a lead groove inside the presser lifting shaft asm. (No. 17). When the presser lifting shaft asm.
Page 186: Adhesives Application Spots
(Caution) There is a grease groove inside the spreader lon- gitudinal metal (No. 22). When the spreader longi- tudinal shaft (No. 18) is pulled out, fill this groove section with JUKI Grease B. (3) Adhesives application spots • Needle clamp After degreasing the threaded part of the needle clamp, apply “Loctite 242”...
Page 187: Troubles And Corrective Measures
14. Troubles and corrective measures WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Trouble Cause (1) Cause (2) Check and corrective measures 1. Thread breakage 1-1) Threading 1-A) Thread caught in thread guide, Incor- Refer to threading diagram.
Page 188 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Trouble Cause (1) Cause (2) Check and corrective measures 2. Looper thread breakage 2-1) Thread guide 1-A) Resistance produced by flaw, burr, Remove the flaw, burr etc.
Page 189 WARNING : Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the sewing machine Trouble Cause (1) Cause (2) Check and corrective measures 3. Needle breakage 3-1) Needle entry 1-A) Needle hits the throat plate or presser Align the needle entry to the needle.
Page 190 WARNING : Turn 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 5. Stitch skipping 5-1) Looper does not scoop 1-A) Looper A-1) Incorrect shape of pointed end of loop- Replace it with the genuine part.
Page 191 WARNING : Turn 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 5-2) Looper does not scoop 2-A) Looper A-1) Incorrect shape of pointed end of loop- Replace it with the genuine part.
Page 192 WARNING : Turn 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 5-3) Looper does not scoop 3-A) Looper A-1) Incorrect shape of pointed end of loop- Replace it with the genuine part.
Page 193 WARNING : Turn 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 5-4) Needle does not scoop 4-A) Looper A-1) Ventral shape is incorrect.
Page 194 WARNING : Turn 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 5-5) Skipping in top covering 5-A) Spreader A-1) Incorrect shape of pointed end of Replace it with the genuine part.
Page 195 WARNING : Turn 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 5-6) Skipping in top covering 6-A) Needle A-1) Needle bend, improper needle attach- Replace the needle with the new one,...
Page 196 WARNING : Turn 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 5-7) Skipping in top covering 7-A) Spreader A-1) Incorrect shape of pointed end of Replace it with the genuine part.
Page 197 WARNING : Turn 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 5-8) Single chain thread cast- 8-A) Needle A-1) Needle bend, improper needle attach- Replace the needle with the new one,...
Page 198 WARNING : Turn 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 To the next page...
Page 199 WARNING : Turn 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 5-9) Double bonding stitch 9-A) Throat plate A-1) R of stitch tongue in throat plate is too Replace it with the genuine part.
Page 200 WARNING : Turn 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 From the previous page 10-F) Threading F-1) Incorrect threading Refer to threading diagram.
Page 201 WARNING : Turn 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 From the previous page 12-C) Thread guide C-1) Flaw, burr in slot Replace when modified or its shape is...
Page 202 WARNING : Turn 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 14-D) Top covering thread D-1) Drawing-in amount of top covering Refer to the standard adjustment figures.
Page 203: Drawing Of Table
C 2×ø3.4 drilled hole on the bottom surface, depth 10 (Drill a hole at the time of set-up.) Thickness 1.5 D Installing position of drawer stopper (on the bottom surface) E JUKI logo type Part No. : 13429907 – 189 –...
Page 204: Semi-Submerged Type For The V-Belt Type
C 2×ø3.4 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×ø10.5 drilled hole, ø26 spot facing, depth 3.5 Part No.
Page 205 B ø17 drilled hole C 2×ø3.4 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 Part No. : 70001773 – 191 –...
Page 206: Semi-Submerged Type For The Direct-Drive Type
C 2×ø3.4 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×ø10.5 drilled hole, ø26 spot facing, depth 3.5 Part No.
Page 207: H22, 23 Table-Mount Type For The V-Belt Type
B ø17 drilled hole C 2×ø3.4 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 Part No. : 40043719 – 193 –...
Page 208: H22, 23 Semi-Submerged Type For The V-Belt Type
C 2×ø3.4 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×ø10.5 drilled hole, ø26 spot facing, depth 3.5 Part No.
Page 209: H22, 23 Table-Mount Type For The Direct-Drive Type
B ø17 drilled hole C 2×ø3.4 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 Part No. : 70001882 – 195 –...
Page 210: H22, 23 Semi-Submerged Type For The Direct-Drive Type
C 2×ø3.4 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×ø10.5 drilled hole, ø26 spot facing, depth 3.5 Part No.
Page 211: E11/E22/E23 For The Direct-Drive Type
(9) E11/E22/E23 for the direct-drive type Z-Z (3 locations) A 4×ø3.4 drilled hole on the bottom surface, depth 20 (Drill a hole at the time of set-up.) B ø17 drilled hole C 2×ø3.4 drilled hole on the bottom surface, depth 10 (Drill a hole at the time of set-up.) D 7×ø3.8 drilled hole on the bottom surface, depth 10 (Drill a hole at the time of set-up.) E 3×ø3.8 drilled hole, depth 10 (Drill a hole at the time of set-up.) Part No.
Page 212: E11/E22/E23 For The V-Belt Type
(10) E11/E22/E23 for the V-belt type Y-Y (3 locations) A 4×ø3.4 drilled hole on the bottom surface, depth 20 (Drill a hole at the time of set-up.) B ø17 drilled hole C 2×ø3.8 drilled hole on the bottom surface, depth 10 (Drill a hole at the time of set-up.) D 7×ø3.8 drilled hole on the bottom surface, depth 10 (Drill a hole at the time of set-up.) E 3×ø3.8 drilled hole, depth 10 (Drill a hole at the time of set-up.) F 5×ø20 (Through hole)
Page 213: H22/H23-Ut59 Semi-Submerged Type For The Direct-Drive Type
(11) H22/H23-UT59 semi-submerged type for the direct-drive type Z-Z (4 locations) A 4×ø3.4 drilled hole on the bottom surface, depth 20 (Drill a hole at the time of set-up.) B ø17 drilled hole C 2×ø3.4 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) Part No.
Page 214: U11-Ut59 Semi-Submerged Type For The Direct-Drive Type
C 2×ø3.4 drilled hole on the bottom surface, depth 10 (Drill a hole at the time of set-up.) Thickness 0.5 D Installing position of drawer stopper (on the bottom surface) E JUKI logo type Thickness 1.5 F 4×ø10.5 drilled hole, ø26 spot facing, depth 3.5 Part No.
Page 216 Please do not hesitate to contact our distributors or agents in your area for further information when necessary. * The description covered in this engineer's manual is subject to change for improvement of the Copyright Ⓒ 2012-2013 JUKI CORPORATION commodity without notice.

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