Cam Stack And Shall - Singer 250 Series Service Manual

II
Cam Stack and Shaft (252-257)
Removal :
30
1) Remove
D
2)
Set stitch width lever on • Straight Stitch • .
3)
Set needle posit ion lever on • Righi fl{eedle • .
4)
Loosen screw
A.
5)
Remove cam stack assembly 8 .
Caution on Reassembly:
When reassembl ing cam stack unit 8 , make certa in that the eccentric portion of shaft
C
faces to
the right as shown in fig . 0 .
Gear mesh adjust :
1) Loosen set screw A.
2)
Rotate eccentr ic shaft
C
clockwise unti l there is no play between worm wheel and worm on
shaft but without binding .
3)
Tighten set screw A and check for free movement by turning handwheel for a complete rotation
of worm wheel :
(18
rotations of handwheel).
Note : After th is adjustment check ad justment on sideways setting of needle bar as in
ll!J
then
as in
m -
Pendulum timindg adjust :
Check :
1) Place a piece of paper under needle.
2)
Set needle posit ion lever on • Center Need le • and stitch width lever on maximum stitch width .
3) The correct timing of the pendulum movement of the needle bar can be observed by manually
operat ing the handwheel in the normal operating direction . The point of the needle should move
upward until the needle is completely out of the paper before moving in the lateral direction
and should reach its peak of ascent sl ightly past center of the two extreme positions of the
needle. On the downward stroke all lateral mot ion should cease when the needle point is
3
to
6 mm (.12 to .24) above the throat plate. See fig . J 1. The needle must return into the opposite
needle hole precisely.
Setting:
1)
Loosen sl ightly the two screws
E.
2)
Turn handwheel until cam follower
L
is in a posit ion corresponding to one of the high lobes on
the cam and the needle bar is in its lowest pos ition . Ma intaining the needle bar in its lowest
posit ion , turn the cam stack by hand so that the center po int ol cam follower L Is in line with
the center of the high lobe of the cam as shown in l ig .
K.
FOAM 723 (1172)