SINGER 331K4 - Manual (Page 14)

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Fig. 32. Setting Height of Check Spring
Fig. 33. Adjusting Tension on Check Spring
HEIGHT SETTING
PREPARATION:
Thread the machine.
CHECK:
Turn machine pulley over toward you slowly. When
take-up lever begins to rise^ spring K, Fig. 32 “checks”,
showing a slight dip and a return to its highest position.
Later, as take-up lever approaches top of stroke,
setting the stitch, this “check” spring K should be drawn
all the way down. As lever descends, check spring K
returns to rest.
TO SET THE CHECK SPRING
SETTING:
To obtain the slight dip in check spring when take-up
begins to rise, loosen screw L, Fig. 32. Turn stud M,
Fig. 32 (at the same time turning entire tension as­
sembly) either over toward left to lower the spring’s
resting position and decrease its movement, or
over toward right to raise the spring’s resting
position and increase its movement. Securely tighten
set screw L.
VARIATIONS (FOR MACHINE 331K4):
Under certain conditions of tacking, it may be neces­
sary to set the check spring higher than it is otherwise
normally set.
TENSION SETTING
PREPARATION:
Thread the machine. Securely tighten set screw L,
Fig. 33. Make certain thumb nut is on stud M, Fig. 33.
CHECK:
Tension on check spring K, Fig. 33, should be suffi­
cient to ensure action at top speed; but still light
enough to permit itself to be drawn all the way down
before any thread is drawn through the tension discs,
as take-up lever approaches height of stroke.
Check spring setting should be reviewed each time a
different foot is applied to machine.
SETTING:
Using a large screwdriver in slot of stud M, turn stud
either over toward left to decrease tension or over
toward right in increase it, as shown in Fig. 33.
VARIATIONS:
The tension on the check spring may require a
different setting, depending upon the thread and
material used. Heavier thread or bulkier material re­
quires more tension to ensure correct thread control.