6.2 Adjusting the needle-thread tension
Pre-tensioner
When the main tensioner 4 and supplementary tensioner 5 are open
(e.g. when the sewing feet are raised) the needle thread must be
under slight residual tension. This residual tension is produced by the
pre-tensioner 2.
The pre-tensioner 2 simultaneously affects the length of the end of the
severed needle thread (the starting thread for the next seam).
–
Basic setting:
Turn knurled nut 2 until its front is flush with the bolt 1.
–
To shorten the starting thread:
Turn knurled nut 2 clockwise.
–
To lengthen the starting thread:
Turn knurled nut 2 anticlockwise.
Main tensioner
The main tensioner 4 should be set to the minimum possible tension.
The looping of the threads must be in the c entre of the material.
With thin material excessive thread tension can cause unwanted
gathering and thread breakage.
–
Adjust the main tensioner 4 so that the stitches are uniform.
To increase tension - turn the knurled nut clockwise
To decrease tension - turn the knurled nut anti-clockwise
Supplementary tensioner
The supplementary tensioner 5 can be switched in to effect a rapid
change in needle-thread tension during operation (e.g. with thickened
seams).
–
Set the supplementary tensioner 5 lower than the main tensioner 4.
–
The supplementary tensioner 5 is switched on and off with the lever 3.
Lever 3 turned to the left = supplementary tensioner is switched
off.
Lever 3 turned to the right = supplementary tensioner is switched
on.
6.3 Opening the needle-thread tensioner
Subclass -170010; -180010
When the sewing feet are raised the main and supplementary
tensioners are also opened automatically.
Subclass -170115; -180115
The needle-thread tensioner is automatically opened when the thread
is severed.
Hint !
(subclass -170115; -180115 only)
The time when the thread-tensioner is opened can be set with
parameters F-191 and F-192 (technician level).
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