JUKI MF-7900-E11 User manual

vi
INSTRUCTION MANUAL
MF-7900-E11

i
CONTENTS
1. SPECIFICATIONS........................................................................................................................ 1
2. ADJUSTMENT PROCEDURE OF ENGAGEMENT AMOUNT OF KNIVES ............................... 1
3. ADJUSTMENT PROCEDURE OF THE KNIFE PRESSURE ...................................................... 2
4. ADJUSTMENT PROCEDURE OF KNIFE CUTTING POSITION ................................................ 2
5. ADJUSTING THE ENGAGEMENT ANGLE OF THE KNIFE....................................................... 3
6. REPLACEMENT PROCEDURE OF MOVING KNIFE AND FIXED KNIFE................................. 4
7. ADJUSTMENT PROCEDURE OF CLOTH GUIDE ..................................................................... 4
8. ADJUSTMENT PROCEDURE OF FRONT-UP AMOUNT OF THE PRESSER FOOT................ 5
9. ADJUSTMENT PROCEDURE OF THE POSITION OF THE TAPE GUIDE................................ 5
10. INSTALLING THE ACCESSORIES (TAPE GUIDE BASE, TENTION ROLLER AND SUCTION
PIPE) SUPPLIED WITH THE MACHINE ..................................................................................... 6
11. ADJUSTING PROCEDURE OF THE POSITION OF THE TENSION ROLLER.......................... 8
12. ADJUSTING PROCEDURE OF THE POSITION OF THE TAPE GUIDE BASE....................... 10
13. HOW TO USE THE KNIFE CANCELLING MECHANISM......................................................... 14
14. DRAWING OF TABLE ............................................................................................................... 15

– 1 –
1. SPECIFICATIONS
When adjusting the engagement, perform the work after
conrming regarding the height of xed knife ❸that the
upper surface of the fixed knife is flush with the upper
surface of the throat plate or the former is installed slightly
lower than the latter.
Loosen setscrew ❶in the state that moving knife ❷comes
down to its lowest position, and adjust the engagement
amount of the moving knife and xed knife ❸ to approximate-
ly 0.5 mm.
2. ADJUSTMENT PROCEDURE OF ENGAGEMENT AMOUNT OF KNIVES
Model MF-7900-E11
Class name Right-hand fabric undertrimmer for pre-closed elastic attaching with tension roller
Application Pre-closed waist elastic attaching of men's brief, trunks, etc.
(Waist elastic width up to 40 mm)
Sewing speed
Max. 5,000 sti/min (provided with PL12 or PL13)(at the time of intermittent operation)
Speed of stitch at the delivery. 4,000 sti/min(provided with PL12 or PL13)
(at the time of intermittent operation)
Needle gauge
3-needle 5.6 mm, 6.4 mm
2-needle 4.0 mm
Feed ratio 1 : 0.7 to 1 : 1 (Pitch less than 2.5 mm)
Stitch length 0.9 to 3.6 mm (Adjustable 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 sti/min.
❶
❸
0.5 mm
❸ ❷
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the follow-
ing work after turning the power off and ascertaining that the motor is at rest.

– 2 –
Adjust the distance between the right needle and the cut-
ting position as described below.
1) Loosen setscrews ❶, ❷, and ❸, and move moving
knife and xed knife to the right and left to adjust the
distance.(The knife will not move unless setscrews ❶
and ❷ are loosened.)
2) After the adjustment, tighten setscrew ❷and setscrew
❶ in the written order.
After the adjustment, the knife pressure changes. Adjust
the knife pressure appropriately referring to "3. ADJUST-
MENT PROCEDURE OF THE KNIFE PRESSURE"p.2.
4. ADJUSTMENT PROCEDURE OF KNIFE CUTTING POSITION
❷
❸
❶
Make the engagement pressure of moving knife and xed
knife as low as possible within the range of smooth cutting
of fabric. Loosen setscrew
❶
of striker Aand setscrew
❷
of striker B in the written order. Shift striker B to the right
and tighten setscrew
❷
to increase the knife pressure.
Once the desired knife pressure is achieved, tighten set-
screw
❶
.
3. ADJUSTMENT PROCEDURE OF THE KNIFE PRESSURE
❷❶
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the follow-
ing 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 the machine, be sure to start the follow-
ing work after turning the power off and ascertaining that the motor is at rest.

– 3 –
1） Loosen setscrew ❶ of the adjusting lever. Adjust the
sharpness of the knife by turning the adjusting lever
counterclockwise according to the sharpness of the
knife.
2）
After the adjustment of the knife sharpness, tighten set-
screw ❶ of the adjusting lever.
3） After the adjustment of the engagement, carry out "3.
ADJUSTING THE UPPER KNIFE PRESSURE" p.2
and "2. ADJUSTMENT PROCEDURE OF ENGAGE-
MENT AMOUNT OF KNIVES" p.1.
4）
In the delivered state of the sewing machine, the posi-
tion of marker dot A orients to the 12 o'clock direction,
as observed from the pulley side, when the knife is in
its lower dead point. Adjust to decrease the angle of
mesh bit by bit such as from 12 o'clock to 11 o'clock,
then to 10 o'clock.
1. The extent of the adjustment of the angle of
mesh is until marker dot A is turned coun-
terclockwise to reach the horizontal posi-
tion. If the lever is turned beyond the above,
the angle between the upper knife and the
lower knife will increase.
2. If the depth of engagement is excessively
increased, the knife can wear.
3. Adjust the knife so that it cuts well and the
depth of engagement is not excessive
Counterclockwise turn
❶
Marker dot A
B: Standard adjustment angle
C:
Angle adjusted for hard-to-sew materials
D:
Angle adjusted when the knife has worn
* If the knife engagement angle is adjusted to
D from the start, the knife can wear earlier
than the case where the angle is adjusted
the standard one.
Horizontal
position
B
C
D
Marker dot A
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 follow-
ing work after turning the power off and ascertaining that the motor is at rest.

– 4 –
Remove setscrew ❸ and remove the old moving knife.
Press arrow mark plane Aof new moving knife ❶to the ma-
chined plane of knife holder ❷, and tighten it with setscrew
❸.
When replacing fixed knife ❺, loosen setscrew ❹, and
remove the xed knife in the lower direction. Insert the new
xed knife from the lower direction and x it. At this time, x
the xed knife with setscrew ❹ after conrming regarding
the height of xed knife that the upper surface is ush with
the throat plate or slightly lower than the throat plate.
When knife holder ❷is removed, perform the adjustment
of engagement again.
6. REPLACEMENT PROCEDURE OF MOVING KNIFE AND FIXED KNIFE
Adjust the position of cloth guide ❶in accordance with
the kinds and thickness of the fabric so that the hook knife
can cut the material end at a xed width. Loosen setscrew
❷, and move the cloth guide to the right and left to adjust
the position.
7. ADJUSTMENT PROCEDURE OF CLOTH GUIDE
❶
❷
❸
❹
❺
A
❶
❷
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the follow-
ing 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 the machine, be sure to start the follow-
ing work after turning the power off and ascertaining that the motor is at rest.

– 5 –
❷
❸
❶
8. ADJUSTMENT PROCEDURE OF FRONT-UP AMOUNT OF THE PRESSER FOOT
When sewing a thick rubber sheet or the like together, fab-
ric can be smoothly fed by raising the front of presser foot
❶. Loosen nut ❷, turn setscrew ❸ to the right (clockwise),
and raise the front of presser foot for adjustment.
9. ADJUSTMENT PROCEDURE OF THE POSITION OF THE TAPE GUIDE
Loosen setscrew ❶, and move tape guide base ❷to the
right and left to adjust the position of the tape.
❷
❶
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the follow-
ing 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 the machine, be sure to start the follow-
ing work after turning the power off and ascertaining that the motor is at rest.

– 6 –
10. INSTALLING THE ACCESSORIES (TAPE GUIDE BASE, TENTION ROLLER AND
SUCTION PIPE) SUPPLIED WITH THE MACHINE
(1) Installing the guide roller
(2) Installing the bottom roller of the tension roller
1) Adjust presser guide asm. ❸ to the installing hole, and
x it with screws ❶and ❷.
1) Install bottom roller plate ❶with three wood screws ❷.
For the installing position of the bottom roll-
er plate, refer to the drawing of the table.
Fix front roller general asm.
❶
with setscrew
❷
.
(3) Installing the front roller
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the follow-
ing work after turning the power off and ascertaining that the motor is at rest.
❶❷
❷
❶
❸
❷
❶

– 7 –
(4) Installing the rear roller
❶
❷
❸❹❺❻
1) Fix rear roller plate base
❶
with three wood screws
❷
.
For the installing position of the rear roller
plate base, refer to the drawing of the table.
2) Install rear roller asm.
❸
to rear roller plate base
❶
with
screw
❹
(M8), washer
❺
and clamp lever
❻
.
(5) Installing the suction pipe
１）
Fix suction pipe retaining plate
❶
with setscrews
❷
.
❶
❷
2) Install suction pipe ❶with screw ❷and washer ❸.
Secure suction pipe retaining plate ❺and suction pipe
❶ with cable clip ❹.
❸
❶
❺
❹❷

– 8 –
Adjust so that the right-hand end of the elactic band meets
the left-hand side of collar
❺
of the front roller and collar
❸
of the intermediate roller when putting straight the elac-
tic band on the front roller. Adjust in accordance with the
procedure below.
1) Loosen two screws ❶, adjust elactic band guide ❹to
the elactic band width, and tighten two screws ❶.
2) Loosen screw ❷, adjust collar ❺to the position of the
right-hand end of elactic band, and tighten screw ❷.
3) Loosen screw ❻ in collar ❸ of the intermediate roller,
and move collar ❸ to the right or left in accordance
with the elactic band width. At this time, make sure that
the elactic band is put straight. Then tighten screw ❻.
Do not excessively tighten screws ❶and ❻.
Deformation of collars will be caused.
11. ADJUSTING PROCEDURE OF THE POSITION OF THE TENSION ROLLER
(1) Adjusting the lateral position
❹
❶
❷
❺
Elactic band
❻
❺
❸
(2) Adjusting the vertical position and longitudinal position of the tension roller
Loosen clamp lever ❶and screw ❷. Adjust the height
and longitudinal position of the front roller.
After the adjustment, tighten clamp lever ❶and screw ❷.
❶
❷
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the follow-
ing work after turning the power off and ascertaining that the motor is at rest.
Contact

– 9 –
(3) Adjusting the longitudinal position
1) Adjusting the lateral position
Loosen three screws ❶, adjust the bottom roller so
that the elastic band is put straight, and tighten three
screws ❶.
2) Adjusting the vertical position
Loosen clamp lever ❷, adjust the position so that the
elastic band is appropriately in accordance with the
length of it, and tighten clamp lever ❷.
(4) Adjusting the position of the bottom roller
Adjusting the longitudinal and vertical positions
Loosen clamp lever ❶, adjust the position so that the
elastic band is appropriately tense in accordance with
the length of it, and tighten clamp lever ❶.
❶
❷
❸
❶

– 10 –
(1) Adjusting the position of the guide roller
1) Adjusting the vertical position
Loosen screw ❶, and adjust so that the top surface of
support bracket ❷ is lower by 0.5 mm than the top sur-
face of bracket ❼. Then tighten screw ❶. (Fig. 1)
2) Adjusting the longitudinal position
Loosen lever ❸, and adjust bracket ❹so that distance
Cbetween front end Aof support bracket ❷and shaft
center B of the roller is approx. 30 mm. Then clamp le-
ver ❸. (Fig. 2)
3) Adjusting the lateral position
Loosen screw ❺, adjust the left edge of collar ❻to the
right-hand side of the elastic, and tighten screw ❺. At
this time, adjust so that left-hand edge ❽ of front roller
aligns with the elastic guide of the presser. (Fig. 3)
12. ADJUSTING PROCEDURE OF THE POSITION OF THE TAPE GUIDE BASE
0.5 mm
❶
❸
❹
❷
❺
❻
❼
❼
❷
❹
❸
❷
A
B
Fig.1
Fig.2
Fig.3
C : Approx. 30 mm
C
Elactic band
WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the follow-
ing work after turning the power off and ascertaining that the motor is at rest.
❺
❻
❽

– 11 –
1) Adjusting the lateral position
Loosen screw ❶, adjust presser guide ❷to the right-
hand side of the elastic band, and tighten screw ❶.
(2) Adjusting the elastic guide
❶
❸
A : Approx. 41 mm
B : Approx. 60°
❷
A
B
2) Adjusting the angle and length
Loosen screw ❸, and adjust presser guide ❷so that
the distance from the bottom of installing section is
approx 41 mm and the inclination from the horizontal
position is approx 60˚. Then tighten screw ❸.

– 12 –
2) Adjusting the vertical position
Loosen screw ❻, and adjust bracket ❼to the position
of approx. 7.5 mm from the top surface of the cover ❽.
Then tighten screw ❻. (Fig.2)
1) Adjusting the lateral position
Loosen screw ❶and screw ❷, and adjust presser bar
❺ so that the clearance between cloth presser ❸and
knife ❹ is 0.5 mm. Then tighten screw ❶and screw ❷.
(Fig.1)
❶
❻
A
❼
(3) Adjusting the elastic band presser plate
❼
A : Approx. 7.5mm
Fig. 2
❹
0.5 mm
❷
❸
❺
❺
Fig.1
❽

– 13 –
3) Adjusting the position of lever ❷
Loosen screw ❶, and adjust so that the clearance
between lever ❷and the top surface of presser ❸is 3
mm. Then tighten screw ❶.
4) Position of the stopper ❷
Loosen screw ❶, and adjust stopper ❷to the position
before it comes in contact with lever ❸. Then tighten
screw ❶.
❶
❷
❸
3 mm
❸
❶
❸
❷
5) Adjusting the presser plate pressure
Adjust the presser pressure by loosening screw ❶and
turning collar ❷.
• When collar ❷is turned to side A, the presser pressure
is increased.
• When collar ❷is turned to side B, the presser pressure
is decreased.
After the adjustment, tighten screw ❶ to x the collar.
❷
❶A
B

– 14 –
1) Depress lever
❶
until it will go no further. Moving knife
❸
moves to the position which is lower than throat
plate
❹
.
2) Keeping lever
❶
held in the fully-depressed position,
press button
❷
to release lever
❶
.
3) Moving knife
❸
is xed in the aforementioned position
which is lower than the throat plate
❹
. To use moving
knife
❸
again, slightly depress lever
❶
. Moving knife
❸
will be brought to the previous position and lever
❶
and button
❷
will be returned to their home position by
the spring.
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 follow-
ing work after turning the power off and ascertaining that the motor is at rest.
❶
❸
❹
❷

– 15 –
14. DRAWING OF TABLE
70003387 MF-7900-E11/E22/E23 For the direct-driven machine head
A4 x ø3.4 on the bottom surface, depth 20 (Drill a hole at the time of set-up.)
B3 x ø3.8 on the top surface, depth 10 (Drill a hole at the time of set-up.) (Rear roller mounting base hole) C
Drilled hole 17
D7 x ø3.8 on the bottom surface, depth 10 (Bracket mounting hole) E2 x ø3.4 on the bottom surface, depth 10 (Drill a hole at the time of set-up.)
ABC
D
E
Z-Z (3places)

– 16 –
70003388 MF-7900-E11/E22/E23 For V belt
AB
C
D
E
F
G
H
I
A 4 x ø3.4 on the bottom surface, depth 20 (Drill a hole at the time of set-up.)(Table-stand installing position) B 4 x ø3.8 on the top surface, depth 10 (Drill a hole at the time of set-up.) (Drill a hole at the time of set-up.) C
Drilled hole 17
D 5xø20 (Passing through) E ø50 (Passing through)
F 3 x ø3.8 on the bottom surface, depth 10 (Drill a hole at the time of set-up.)(Bracket mounting hole)
G 2 x ø3.8 on the bottom surface, depth 10 (Drill a hole at the time of set-up.)(Bracket mounting hole) H 2 x ø3.8 on the bottom surface, depth 10 (Drill a hole at the time of set-up.)(Bracket mounting hole) I 2 x ø3.8 on the bottom surface, depth 10 (Drill a hole at the time of set-up.)(Pushbutton switch mounting position)
Y-Y (3places)