Operation Manual

Operating Instructions 650-10 - 02.0 - 10/201528
4.8 Setting hook thread tension
Proper setting
The hook thread tension must be set so that the resulting seam
pattern looks like the figure in  4.4 Setting the needle thread
tension, p. 23.
At the recommended hook thread tension of e.g. 25 g (measured
with a full bobbin), 12.5
g should be generated by the braking
spring and 12.5 g by the tensioning spring.
The basic setting for the tensioning spring is performed as follows:
When the bobbin case contains a full bobbin it must sink slowly
under its own weight.
Fig. 11: Bobbin case sinking
The braking spring prevents the bobbin running on when the
thread has been cut.
WARNING
Risk of injury from moving parts!
Crushing is possible.
Switch off the machine before you set the hook
thread tension.