17.Adjusting the tension of bobbin thread and needle
thread(Fig.14)
Normal stitch form should be as shown in Fig.14 A.
When abnormal stitches occur with puckering or thread
breakage,the tension of bobbin thread and needle thread
should be adjusted accordingly.
1.If the stiches are as shown I Fig.14 B,which means
that the tension of the needle thread is too strong or
the tension of the bobbin thread is too weak,turn the
tension regulating thumb nut counter clockwise to
weaken the tension of the needle thread, or tighten the
bobbin case tension regulating screw with small
screwdriver to strengthen the tension of the bobbin
thread.
2.If the tension of the needle thread is too weak or the
tension of the bobbin thread is too strong as shown in
Fig.C,turn the tension regulating thumb nut clockwise
to strengthen the tension of the needle thread,or loosen
the bobbin case regulating screw with small screwdriver
to weaken the tension of the bobbin thread.
18.Adjusting the swing range and the tension of the
thread take-up spring(Fig.15)
14
15
6
L o o s e n
T i g h t e n
S t r e n g t h e n
W e a k e n
T e n s i o n o f
n e e d l e t h r e a d
B
A
B
A
C
B
Generally,before delivery,the thread take-up spring should
have been adjusted properly.
Therefore, it should be
re-adjusted only when sewing with special material or
special thread.
Loosen the thread take-up spring shaft adjusting nut B,
then turn the thread take-up spring shaft A to adjust its
tension. Turn the thread take-up spring shaft couter
clockwise to strengthen the tension of the thread take-up;
on the contrary,to weaken the tension of the thread take-up.
Tighten the adjusting nut B.
Loosen the position plate screw, turn the thread take-up
position plate counter clockwise to widen the range of the
thread take-up spring;on the contrary,to narrow the range
of the thread take-up spring. After adjustment,tighten the
position plate screw.
