Singer 628 - Cam Stack and Selectors; Removal and Replacement; Timing the Cam Stack

CAM STACK
SPRING
SCREW
STUD
CAM STACK
CLASS 626 MACHIN ES: This class of machine is designed
for use only with the factory-installed standard cam stack,
and is provided only with a Front Cam Selector Arm. Ac¬
cordingly, removal and replacement of cams in this ma¬
chine should be performed only by authorized servicemen
during regular maintenance periods, and those instructions
referring to Rear Com Selector Arm do not apply to Class
626 Machines.
CLASS 628 MACHINES: This class of machine is designed
for use only with one replaceable Fashion Disc stitch-
pattern cam during any one sewing operation, and is pro¬
vided only with a Front Cam Follower. Accordingly, those
instructions referring to Cam Stack Removal and Replace¬
ment, Adjustments, and Stops do not apply to Class 628
Mach ines.
Removal and Replacement
Set stitch pattern selector at “A — K”.
Remove arm top cover and removable Fashion
Disc fstitch-oattern cam).
Remove large screw-stud with its spring.
Remove cam stack.
Replace cam stack, meshing worm wheel of cam
stack with worm of arm shaft.
Reolace screw-stua with its SDring.
Replace Fashion Disc ana arm rop cover.
Aai u srmenrs
i iming the Cam Stack
Remove arm top cover and Fashion Disc, and
large screw-stud with its spring.
Using stitch-pattern selector, bring rear follower
in contact with edge of top cam of cam stack.
Turn hand wheel over toward operator until timing
mark is at point of contact with rear follower, as
shown.
At this setting, the needle bar should be at its
lowest position.
Loosen each of the three clamping screws on top
of cam stack.
While holding needle bar at its lowest position,,
manually rotate entire cam stack clockwise until
timing mark reaches point of contact with rear follow¬
er, as shown.
Tighten the three clamping screws.
Replace stud with its spring. Tighten stud.
Replace Fashion Disc and arm top cover.
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