Operation
Operating Instructions 650-10 - 03.0 - 08/2016 29
4.7.2 Setting hook thread tension
Proper setting
The hook thread tension must be set so that the resulting seam 
p
attern looks like the figure in ( p. 27).
At the recommended hook threa
d tension of e.g. 25 g (measured 
with a full bobbin), 12.5 g should be generated by the braking 
sp
ring 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 
u
nder its own weight. 
Fig. 10: Setting the hook thread tension (1)
The braking spring prevents the bobbin running on when the 
thread has been cut.
CAUTION
Risk of injury from sharp and moving parts!
Cutting or crushing possible.
Switch off the machine before setting the hook 
th
read tension.