Duerkopp Adler 579 Operations Instructions download pdf (Page 14)

4. Thread tension

4.1 Needle and bobbin-thread tension

The thread tensions depend on the type and quality of the yarn and

material. The thread tension should be the minimum at which the

appearance of the buttonhole is satisfactory.

With thin material excessive thread tensions may cause unwanted

gathering and thread breakage.

Upper-thread tension

The upper-thread tension must generally be set higher than the

bobbin-thread tension. The upper-thread tension consist of two

components the main tension for the sewing process and a residual

tension to keep the upper thread taut for the cut beneath the throat

plate.

The upper thread hanging out of the needle must be long enough to

ensure that the first stitch is securely executed. The residual tension

required to achieve this depends on the elasticity of the upper thread

used.

–

Adjust the main tension for the sewing process with the knurled

nut 1.

–

Adjust the residual tension to keep the upper thread taut when it is

cut with the sleeve 2.

If the residual tension is changed the main tension should be

corrected accordingly.

NB:

Adjusting the thread clamp 4 does not alter the upper-thread tension.

Only the clamping force can be adjusted on the thread clamp.

Bobbin-thread tension

–

Swing the head up.

–

Adjust the bobbin-thread tension with the tensioner 3.

–

Swing the head down.

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Duerkopp Adler 579 Operations Instructions Page 14