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4.10 Thread tension
16
The machine head has been set in the factory for sewing buttonholes
with flat bartacks and with raised lips.
Pre-tension
The pre-tension 4 is always active. It serves for stabilising the needle
thread. It should be set to the minimum value ( 5-10 g ). The
pre-tension 4 has scarcely any influence on the seam pattern.
Main tension
The main tension 5 is active when sewing both buttonhole lips. But the
main tension 5 it is out of action when bartacking and when cutting the
threads.
Bartack tension
The bartack tension 6 is opened only when cutting the threads. It is
remains closed during the entire remaining sewing process.
Buttonhole lip tension
The buttonhole lip tension is produced jointly by the main tension 5
and by the bartacking tension 6. About 1/3 of the buttonhole lip tension
should be produced by the bartacking tension 6.
Adjustment
–
Thread the needle thread so that it does not pass through the main
tension 5.
–
Start the sewing process.
4
5
6
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