JUKI MF-7700 Series Quick start guide

R
ENGINEER’S MANUAL
13371604
No.E361-01
High-speed, Flat-bed Coverstitch Machine
MF-7700 Series

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 instructions in detail. And this manual describes “Standard Adjustment”, “Adjustment
Procedures”, “Results of Improper Adjustment”, and other important information which are not covered by the Instruction
Manual.
It is advisable to use the relevant Instruction Manual and Parts List together with this Engineer’s Manual when carrying
out the maintenance of these machines.
In addition, for the motor for the sewing machine with thread trimmer, refer to the separate Instruction Manual or
Engineer’s Manual for the motor. And for the control panel, refer to the Instruction Manual for the control panel.
This manual gives the “Standard Adjustment” on the former page under which the most basic adjustment value is
described, and on the latter page “Results of Improper Adjustment” under which stitching errors and troubles arising
from mechanical failures are described together with the “Adjustment Procedures”.

CONTENTS
1. SPECIFICATIONS ............................................................................................. 1
2. CONFIGURATION OF THE MACHINE COMPONENTS .................................. 2
3. MODEL NUMBERING SYSTEM ....................................................................... 3
4. MOTOR PULLEY AND BELT MF-7700 Series ................................................ 4
5. STANDARD ADJUSTMENT ............................................................................. 5
(1)Threading the machine head ........................................................................................... 5
(2) Adjusting the rocking thread take-up............................................................................. 7
(3) Adjusting the position of the needle thread guide rod ................................................. 9
(4) Adjusting the position of the thread receiver .............................................................. 11
(5) Adjusting the position of the spreader thread guide and spreader thread take-up ...... 13
(6) Adjusting the spreader .................................................................................................. 15
(7) Adjusting the timing relation between the looper and needle bar............................. 19
(8) Retuming amount of the looper .................................................................................... 21
(9) Height of the needle ....................................................................................................... 23
(10) Locus and longitudinal motion of the looper ............................................................ 25
(11) Adjusting the needle guard ......................................................................................... 27
(12) Instlling cover of the looper and needle guard after adjusting ................................ 31
(13) Adjusting the feed dog................................................................................................. 33
(14) Adjusting the feed relation .......................................................................................... 39
(15) Adjusting the presser foot........................................................................................... 41
(16) Adjusting the micro-lifter............................................................................................. 43
(17) Adjusting the looper thread cam ................................................................................ 45
(18) How to change needle bar stroke ............................................................................... 47
(19) How to change the spreader ....................................................................................... 51
(20)With reagard to lubrication .......................................................................................... 53
(21) Adjusting and setting SC-380...................................................................................... 55
6. TROUBLES AND CORRECTIVE MEASURES............................................... 57
7. DRAWING OF TABLE (SEMI-SUBMERGED TYPE) ..................................... 71

–1–
No. Item Specifications
1 Model name High-speed, flat-bed coverstitch machine
2 Model MF-7700 series
3 Stitch type ISO standard 406, 407, 602, and 605
4 Example of application Hemming and covering for knits and general knitted fabrics
5 Max. sewing speed Max. 6,500 rpm (at the time of intermittent operation)
6 Needle gauge 3-needle ... 4.8 mm, 5.6 mm, and 6.4 mm
2-needle ... 4.0 mm (3.2 mm can be accepted as special order)
7 Differential feed ratio 1 : 0.7 to 1 : 2 (stitch length : less than 2.5 mm)
Micro-differential feed adjustment mechanism is provided. (Micro-adjustment)
8 Stitch length 1.2 mm to 3.6 mm (can be adjusted up to 4.4 mm)
9 Needle UY128GAS ORGAN #9S to #14S (standard #10S)
(SCHMETZ Nm65 to Nm90, standard Nm70)
10 Needle bar stroke 31mm (standard), possible up to 33 mm by adjustment)
11 Dimensions (Height) 451 x (Width) 515 x (Length) 265
12 Weight 46kg
13 Lift of presser foot 8 mm (needle gauge : 5.6 mm without top covering), and 5 mm (with top covering)
Micro-lifter mechanism is provided.
14 Feed adjustment method Main feed ... dial type stitch pitch adjustment method
Differential feed ... lever adjustment method (micro-adjustment mechanism is provided.)
15 Looper mechanism Spherical rod drive method
16 Lubricating system Forced lubrication method by gear pump
17 Lubricating oil JUKI MACHINE OIL 18 (Equivalent to ISO VG18)
18 Oil reservoir capacity Oil gauge lower line : 600 cc to upper line : 900 cc
19 Installation Semi-submerged type
20 Needle tip, needle thread and Provided as standard
silicon oil lubricating unit
21 Noise Workplace-related noise at sewing speed
n= 5000 min-1 : LPA ≦78 dB (A)
Noise measurement according to DIN 45635-48-A-1.
1. SPECIFICATIONS

–2–
2.CONFIGURATION OF THE MACHINE COMPONENTS
1Presser spring regulator !0 Thread tension nut !9 Thread trimming knife
2Needle bar thread take-up cover !1 Oil gauge @0 Rocking thread take-up receiver
3Oil circulation identification window !2 Feed regulating knob @1 Rocking thread take-up
4Oil hole cap !3 Eye guard cover @2 Front cover
5Micro-lifter !4 Throat plate @3 Slide cover
6"Oil" indication !5 Needle tip silicon oil lubricating unit @4 Needle bar thread take-up thread
7Needle thread silicon !6 Differential lock nut receiver
oil lubricating unit !7 Micro-adjustment knob @5
Rocking thread take-up thread guide
8Thread guide No. 1 !8 Finger guard @6 Silicon container thread guide
9Upper pulley @7 Belt cover
12
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9
!0
!1
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@0 @1
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