21
(3) Adjusting the tension of thread take up lever spring
A) Adjusting the thread take up stroke
As in figure 26, loosen the stopper clamp screw
①
, and turn the thread take up lever spring stopper
②
clockwise to
make the stroke smaller and counterclockwise to make it bigger. The thread take up stroke is normally 5~10mm.
B) Adjusting the thread take up tension
As in figure 26, loosen the screw
③
of the thread tension control assembly shaft, and insert the driver into the groove
④
of the thread tension control assembly shaft. Turn clockwise to make the spring tension stronger and counter-
clockwise to make it weaker. The thread take up spring tension is normally 50~80g.
[Figure 26]
5-10mm
small
large
①
②
50~80g
weak
strong
④
③
(4) Adjusting the thread release stroke. (automatic trimming type)
If the upper thread falls out from the needle hole after trimming, check whether the plate
①
opens while the trimming is
in action. For the adjustment of plate opening level, put the solenoid
②
in action, and adjust by moving solenoid collar
③
back and forth to make the opening of the thread tension adjusting plate
①
0.8 mm. Also, when the thread release
solenoid is not in action, check whether the plates are closely adhered to each other. (See figure 27)
[Figure 27]
①
②
①
③
approx. 0.8 mm
[Caution]
If the plates do not open enough during the trimming action even when the assembling is good, check whether or not the
upper thread length adjustment volume, which is at the front of the control box, is low.
