Adjustment Of The Thread Tension - Mitsubishi PLK-E0504 Technical Manual

6-3. Adjustment of the thread tension

The thread tension between the upper and bottom thread should be balanced in the best
condition.
When the upper thread tension is well balanced with the bobbin thread tension, both threads
are interlocked along the centerline of fabric layers as shown on the below figures.
NOTE Normally weaker bobbin thread tension brings better sewing quality.
So it is prefer to set bobbin thread tension first and then set upper thread tension.
○ ○ ○ ○
Well balanced
tension
(1) Bobbin thread tension
Adjust the bobbin thread tension with the thread tension adjusting screw (NO.2) on the
bobbin case (NO.1). The thread tension becomes loose if turn the thread tension adjusting
screw (NO.2) to the counterclockwise, and the thread tension becomes tight if turn it to the
clockwise.
(2) Upper thread tension
Adjust the upper thread tension based on the bobbin thread tension.
For this adjustment, turn the thread tension adjusting nut (NO.3). The upper tread tension
becomes tight if turn the thread tension adjusting nut (NO.3) to the clockwise, and the
upper thread tension becomes loose if turns it to the counterclockwise.
1
× × × ×
The upper thread is tight
or the bobbin thread is loose
2
－18－
× × × ×
The upper thread is loose
or the bobbin thread is tight
3