JUKI MF-7900 Series Engineer's Manual page 119

Adjustment procedures
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 of the adjustment pin and move adjustment
pin ❻ up or down to adjust the stroke of the upper knife.
(4) The standard adjustment position is the position where the
engraved marker line A of adjustment lever ❼ aligns with the
engraved marker line B of adjustment pin ❻ . Loosen nut ❺
and raise adjustment pin ❻ to increase the stroke of the upper
knife, and lower it to decrease the stroke. After the adjustment,
perform "7.-(2)-3. Adjustment procedure of engagement
amount of knives".
6. Adjusting the engagement angle of the knife
(1) Loosen adjusting lever setscrew ❽ . Turn the adjusting lever
clockwise depending on the knife sharpness to adjust it.
(2) After the adjustment of the knife sharpness, tighten adjusting
lever setscrew ❽ .
(3) After the adjustment of the engagement, carry out "7.-(2)-1.
Adjusting the upper knife pressure" and "7.-(2)-3. Adjustment
procedure of engagement amount of knives".
(4) At the time of shipment, the knife has been factory-adjusted so
that the knife is positioned at its upper dead point and marker
dot C points to 12 o'clock direction as observed from the frame
side.
Adjust in such a way to increase the angle gradually from 12
o'clock direction to 1 o'clock direction, then to 2 o'clock direc-
tion.
(Caution) 1. The engagement angle can be adjusted until
marker dot C is brought to the horizontal posi-
tion by turning the adjusting lever clockwise. If
the adjusting lever is turned further, the angle
between the upper and lower knives will be in-
creased.
2. If the depth of engagement is excessively in-
creased, the knife can wear.
3. Adjust the knife so that it cuts well and the
depth of engagement is not excessive.
Results of Improper adjustment
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