Setting The Underthread Tension - Dürkopp Adler Class 271 Instruction Manual

6.6 Setting the Underthread Tension

Setting the underthread tension
The underthread tension must be set so that a seam as shown in Illus. a)
in Chapter 6 results.
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With a recommended underthread tension of e.g. 30g, 15g should be achieved
through the brake spring 1 and 15g through the tension spring 4.
–
The following applies as the base setting for the tension spring 4:
The bobbin case must slowly lower under its own weight. See sketch in Chapter 6.5.
The brake spring 1 hinders a running-on of the bobbin during the thread trimming
sequence.
To regulate the two tension values one proceeds as follows:
–
Turn adjusting screw 3 back so far that the tension of the tension spring 4 is
completely released.
–
Set the brake spring 1 by turning the screw 2 so that half of the recommended
hook thread tension value is achieved through the brake spring.
Attention ! Not for classes: 271-140432, 271-140442, 273-140432
–
Insert the bobbin into the hook base and thread the underthread (see Chapter 6.5).
–
Insert the bobbin case with the bobbin into the hook.
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Turn the handwheel until the sewing machine has conducted a stitch.
–
Pull the underthread to the top of the needle hole with the aid of the needle thread.
–
Pull off the underthread in the direction of sewing at an angle of 45°. About half of
the tension value should be felt.
Then tighten the adjusting screw 3 to the recommended tension value.
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1
4
Caution Risk of Injury !
Turn the main switch off.
Setting the underthread tension only with the sewing
machine turned off.
2
3