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MF-7900D-H25
INSTRUCTION MANUAL
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CONTENTS
1. SPECIFICATIONS ........................................................................................................................................ 1
2. ADJUSTING THE PRESSURE OF THE SLIDING PRESSER FOOT ......................................................... 1
3. ADJUSTING THE SLIDING PRESSER FOOT ............................................................................................ 2
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1. SPECIFICATIONS
Model MF-7900D-H25
Class name Covering stitch machine with left hand fabric undertrimmer
(with a sliding presser foot for extra light-weight materials)
Application Hemming of knit and jersey products
Sewing speed Max. 5,000 sti/min (at the time of intermittent operation)
Speed of stitch at the delivery. 4,500 sti/min (at the time of intermittent operation)
Needle
gauge
Differential feed
ratio
3-needle 5.6 mm, 6.4 mm
2-needle 3.2 mm, 4.0 mm
1 : 0.9 to 1 : 1.6 (stitch length : less than 2.5 mm)
(1 : 0.6 to 1 : 0.9, when the differential link hinge screw is changed)
Micro-differential feed adjustment mechanism is provided. (Micro-adjustment)
Stitch length 0.9 to 3.6 mm
Noise - Equivalent continuous emission sound pressure level (LpA) at the workstation :
A-weighted value of 79.5 dB; (Includes KpA = 2.5 dB); according to ISO 10821-
C.6.2 -ISO 11204 GR2 at 4,000 sti/min.
2. ADJUSTING THE PRESSURE OF THE SLIDING 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.
This presser foot effectively prevents slippage
between upper and lower materials during sewing.
❷
❶
❸
1. Loosen setscrew ❶.
2. The pressure of spring ❸ can be adjusted by
turning adjustment collar ❷.
• In the case the lower material is fed exces-
sively, turn adjustment collar ❷ clockwise to
increase the pressure of spring ❸.
• In the case the upper material is fed exces-
sively, turn adjustment collar ❷ counterclockwise to decrease the pressure of spring ❸.
3. After the adjustment, tighten setscrew ❶ to x
adjustment collar ❷.
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If the pressure of spring ❸ is excessively increased, the sliding presser
foot will lose its slippage-preventive
effect.
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3. ADJUSTING THE SLIDING 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.
To allow sliding presser foot ❶ to function properly, the pressure of presser bar ❷ and that of
spring ❸ of sliding presser foot ❶ have to be well
balanced.
1. Adjust the height of spring ❸ of sliding presser
2. Check to make sure that the sole of sliding
If not, adjust the pressure of presser bar ❷
3. Turn pulley ❺ clockwise to lift needle ❻ to its
4. Place two plies of material under sliding press-
5. Lower needle ❻ until its tip is brought as close
6. Turn micro-lifter collar ❼ so that the center
In this state, x micro-lifter collar ❼ with set-
7. Check to be sure that only bottom section B of
If not, or in the case sliding presser foot ❶
8. Bring needle ❻ to its upper end.
9. Turn adjustment screw ❾ so that bottom
• Bottom section B moves in the direction
• Bottom section B moves in the material
❸
❶
❺
❹
❷
❾
❻
B
❻
A
❶
❼
❽
foot ❶ to approximately 20 mm. Refer to "2.
ADJUSTING THE PRESSURE OF THE SLIDING PRESSER FOOT" p.1 for the adjust-
ment procedure.
presser foot ❶ comes in close contact with the
surface of throat plate ❹.
until the sole of the sliding presser foot comes
in close contact with the throat plate.
upper end.
er foot ❶.
as possible to the material.
of marker dot A inscribed on the right side of
sliding presser foot ❶ is aligned with the center of needle ❻.
screw ❽.
sliding presser foot ❶ moves up and down in
synchronism with the movement of the feed.
moves up and down in whole in synchronism
with the feed movement, carry out the adjustment again.
section B of sliding presser foot ❶ moves in
the material feeding direction by 1 mm when
sliding presser foot ❶ is lifted.
opposite to the material feeding direction by
turning adjustment screw ❾ clockwise.
feeding direction by turning adjustment screw
❾ counterclockwise.
The standard distance from the undersurface of washer to hinge pin is
9.7 mm.
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