JUKI MF-7900 Series Engineer's Manual page 70

WARNING :
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start of the
sewing machine.
2. Adjusting the height of the needle bar
When the needle bar stroke is changed, be sure to adjust the height of the needle bar.
1) Adjust clearances C provided between needles ❽ and needle holes H in the throat plate to equal.
2) Adjust the height of the needle bar so that the top end of the needle eyelet of left needle aligns
with the bottom end of the looper ❸ when the looper moves from the extreme right position to the
left and top end D of looper ❸ protrudes by approximately 1 mm from the left end of left needle,
remove rubber cap ❼ in the face plate, and tighten the needle bar with setscrew ❾ in the needle
bar bracket.
Reference : When the needle is in the highest position, height E from top surface A of the throat
plate to the top end of left needle is as shown in the table below.
2-needle
Needle Height of left
gauge needle E
3.2 10.1
4.0 9.8
4.8 9.3
5.6 8.8
6.4 8.5
C
3. Adjusting the needle guard
A
❶
❸
❶
Standard adjustment
Unit : mm
3-needle
Needle Height of left
gauge needle E
― ―
― ―
― ―
5.6 8.8
6.4 8.5
D
❸
❽
H
❸
❶
1.5 to 2 mm
B
❶
E
❼
❾
4. Adjusting the front needle guard
❷
❶
– 56 –
A
❸
❸
❷