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 centre 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 = s upplementary 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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