Adjusting The Engagement Angle Of The Knife - JUKI MF-7900 Series Engineer's Manual

(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.
❶
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.
B
C
D
Counterclock-
wise turn
Horizontal
position
Marker dot A
Marker dot A
Loosen setscrew ❶ of the adjusting lever.
1.
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 setscrew ❶ of the adjusting lever.
3. After the adjustment of the engagement, car-
ry out "(3) Adjusting the upper knife pressure"
and "(2) Adjustment procedure of engagement
amount of knives".
4. In the delivered state of the sewing machine,
the position 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.
(Caution) 1. The extent of the adjustment of
the angle of mesh is until marker
dot A is turned counterclockwise
to reach the horizontal position.
If the lever is turned beyond the
above, the angle between the up-
per knife and the lower knife will
increase.
2. If the depth of engagement is ex-
cessively increased, the knife can
wear.
3. Adjust the knife so that it cuts
well and the depth of engagement
is not excessive
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