Needle Thread Tension - Singer 250 Series Service Manual

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Needle Thread Tension
Removal of needle thread tension assembly:
1)
RemoveU.
2) Turn 1ension regula1or dial H 10 "O" position against stop.
3) Loosen screw B and remove tension assembly A.
4) Remove screw C. check spring siop 0 and thread guide E.
Caution on reassembly:
a) When reassembling, make certain that regulator dial
H
is turned to left until figure
"O"
is at
top and against stop and extension F of thread guard R enters hole in arm casting .
b) Lower presser fool.
c) Tighten screw B.
d) Position check spring hook G onto check spring stop 0.
Disassembly of needle thread tension:
1)
To disassemble needle thread tension, it is advisable to keep tension stud T in machine.
2) Pull off regulator dial H forward .
3)
Unscrew adaptor K and remove stop washer L. tension spring M and tension spring cup N.
4)
Remove thread guard R, tension discs Z and check • spring P together.
5) Loosen screw B and remove tension stud T together with releasing pin S.
6)
Before reassembling tension stud T. check tension release lever
U
for free movement.
7) Insert tension stud T into arm casting. Slot of stud should be horizontal.
8) Tighten screw B.
9) Insert releasing pin S and check for free movement .
Assembly of needle thread tension:
1)
Assemble check P together with tension discs Z and thread guard R.
Caution:
a) The raised surfaces of discs Z should face eachother.
b) When assembling, check spring hook G of check spring P must be in downward position .
2)
Reassemble tension spring cup N and insert tension spring M.
3)
Insert stop washer L with hook pointing forward and down .
4)
Screw on adaptor
K
and check for draging motion.
If
adaptor
N
moves too easily, tension stud
T is to be spread.
5)
Lower presser b-ar lifter lever V.
Caution :
Turn adaptor K on tension stud T until there is no play but also no tension between the three
tension discs.
6)
Position check spring hook G onto check spring stop 0 .
7) Press on regulator dial H with figure "O" at top and turn to right.
Adjustments :
Refer lo instructions describing the assembly of the needle thread tension .
Adjust check spring stop D:
Set machine for " Straight Stitch" in "Central Needle Position" and "Med ium Stitch Length"
and sew.
Check :
The check spring hook G should be at rest against check spring stop 0 as needle enters fabric
up to its eye.
Setting:
Loosen screw C and move check spring stop 0 11s required (refer to sketch W) . Tighten screw C.
Adjust check spring tension:
Set machine for "Straight Stitch" in "Central Needle Position " and "Medium Stitch Length"
and sew.
Check:
Tension on check spring P should be just sufficient to take up slack of needle thread until point
of needle reaches fabric .
Tension of check spring P is correctly set alter taking it off stop 0, it hangs down in between
4
and 6 o'clock position.
Setting :
1) Turn regulator dial H to left to "O" position (stop).
2)
Loosen screw
B
and remove needle thread tension assembly
A.
3)
Move tail V of check spring P to increase tension (
+ ).
or to decrease tension (-). as shown
in sketch
a.
4)
Reassemble needle thread tension assembly
A
and tighten screw
B.
5) Position check spring hook G onto check spring stop 0.
FORM 7Z3 (1172) 25