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Fitting seam
Decorative seam
3
Stitch knitting
Stitch knitting
1
2
6.4 Regulating the thread tension
The thread tension must conform to the thickness of the sewn
threads, thickness and hardness of sewn material (thin and
soft material will fold with high tension) and the kind of seam.
An ordinary fitting seam should be formed with stitches knit-
ted in the middle of the sewn material.
A decorative seam is mostly used with rough threads (20) on
thin material and it has tied up threads on the reverse side of
the material for achieving a decorative appearance.
Thread tension adjustment is by standard sewing (par. 5, ta-
ble 3) conditions in accordance with table No. 4.
If achieving of a decorative seam with stitch knitting on the
underside is wished, it is necessary to decrease the upper
thread tension, it is carried out by turning of nuts (1), in the
counter-clockwise sense.
Thread tension
Table 4
Sewing
Kind of seam
category
1
-
2
-
Fitting
3
Decorative
If the maximum lower thread tension exceeds the
values given in table No. 4, it may cause problems
in the beginning of sewing after the previous
thread trim.
Measurement of tension is done by dynamometer.
Warning:
The upper thread tensioner has been loosened automatically
after every trimming and top roller lifting. In these cases the
thread tension cannot be measured.
Regulating the thread tension
Caution! Risk of injury!
Before regulating the lower thread tension, turn
the main switch off and wait until the motor stops.
The upper thread tension is adjusted with nuts (1). Its clock-
wise turning increases the tension.
The tension of the auxiliary tensioner (3) should be as low as
possible but it should be on a level so that the upper thread
would not pull out of the tensioner when the work is being
removed.
The lower thread tension is adjusted with a screw (2). Its clock-
wise turning increases the tension.
Tension correlation rate defines the depth of the seam tied
through. The result of raising the upper tension will be the
decreasing depth of tie through. The opposite will apply with
the lower thread.
6
Identified
Maximum
value upper
tension of
thread tension lower thread
N
N
3
1
4.5
1.5
8
2
5
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