JUKI MF-7900 Series Engineer's Manual page 47

Adjustment procedures
1. Adjusting the height of the feed dog
(1) Loosen setscrew ❼ in the differential feed dog and setscrew ❸
in the main feed dog, and adjust the height.
(2) Adjust the top surface of throat plate ❶ and the height of the
rear end of main feed dog ❷ to 1 ± 0.1 mm when feed dogs ❷
and ❹ come to the highest position, and fix the main feed dog
with setscrew ❸ in the main feed dog.
(3) For the height of differential feed dog ❹ , adjust the height of
front end ❺ of main feed dog ❷ and rear end ❻ of differential
feed dog ❹ , and fix the differential feed dog with setscrew ❼
in the differential feed dog.
2. Adjusting the tilt of the feed dog
(1) Remove 10 setscrews ❾ in bed top cover ❽ , and remove bed
top cover ❽ .
(2) Adjusting procedure of the tilt
1) Loosen setscrews  in the feed lift lever.
2) When turning collar  in the direction of A, the feed dog
moves in the direction of C and is in the front-up state.
3) When turning collar  in the direction of B, the feed dog
moves in the direction of D and is in the front-down state.
4) After the adjustment, tighten setscrews  in the feed lift
lever.
(Caution) After the adjustment check the height of feed dogs ❷
and ❹ .
Results of Improper adjustment
◦ When the position of the feed
dog is high, stitch skipping, de-
fective chain-off, return of feed,
etc. will be caused.
Throat plate comes in contact
with feed dog and damage of
components or abnormal noise
will be caused.
◦ When the position of the feed
dog is low, the stitch length be-
comes short when the sewing is
finished and performance of get-
ting over the overlapped section
is deteriorated.
◦ When the position of the feed
dog is excessively low, looper
and feed dog may come in con-
tact with each other.
◦ When the tilt of the feed dog is
raised toward you, performance
of catching material is improved.
◦ When the tilt of the feed dog is
lowered toward you, it is effec-
tive in irregular stitches and
puckering.
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